Comments sought on new build: A CNC Router for RC Gliders and Planes

[njhussey]

Cheers, yes the draught excluder went on fine. I did give the rails a good clean with thinners first and they stuck to the rail like s*^t to a blanket...so to speak!

[njhussey]

Well I spoke a little too soon. I did press them all down firmly before pouring and still had a couple of leaks. As soon as the epoxy finds a leak path it lifts the draft excluder. Spent 1/2hr chasing 2 leaks...managed to stop them with some blue paper towel and masking tape. After 1/2hr the epoxy is slightly more viscous and stops running (famous last words) as much. Going to check in another 1/2hr to make sure no more is leaking out.

I used 1kg (mixed) for the rails and the gantry. I'd guess the rails are 4-5mm thick and the gantry 2-3mm. The large container (like an ice cream container) I used was ideal as the epoxy didn't get warm at all after mixing. I was quite vigorous in mixing and there were quite a few bubbles but the 7mm hole I drilled in the side of the container coupled with pouring it from about 12" high eliminated nearly all the bubbles. So if you're pouring it do it from a height so it pours in a really thin stream and it gets all the air out. Pics below.

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[EddyCurrent]

Pity about the leaks, someone posted a video of using epoxy and the idea was to pour a thin layer first, this would both find and plug leaks for the final layer.
The 7mm hole works great, anyway it looks like a great job, nice and flat and clear. Remember to give it plenty of time before bolting the rails on, you don't want it compressing slighty like mine did after 3 days.
It's a great feeling when you've passed this stage of the construction, it's like getting past the foundations when building a house and the epoxy is the damp course.

[njhussey]

Pity about the leaks, someone posted a video of using epoxy and the idea was to pour a thin layer first, this would both find and plug leaks for the final layer.
The 7mm hole works great, anyway it looks like a great job, nice and flat and clear. Remember to give it plenty of time before bolting the rails on, you don't want it compressing slighty like mine did after 3 days.
It's a great feeling when you've passed this stage of the construction, it's like getting past the foundations when building a house and the epoxy is the damp course.

Given more time I'd have done it in a couple of pours and spent more time sealing and doing the moat. I'll be leaving it all week to cure (if I can curb my impatience) before doing anything more to it. I've got to cut all the linear rails to length as the X axis are 100mm too long (now wishing I'd extended the rails 100mm further forward but next time...) and the Y & Z are in one length at the moment so that will keep me busy for the next few lunchtimes.

I'm feeling like real progress has been made now the epoxy has been poured. Should be able to get it home and start working on it in the shed after the Honeymoon. I discovered that I can run my pillar drill from my inverter and shed's solar power so I'm happy with that, free (apart from the set up cost) electrickery!!

[EddyCurrent]

I knew someone who used to have batteries and DC lighting in his shed, but he just kept taking the batteries to work to recharge them. :glee:

[njhussey]

I knew someone who used to have batteries and DC lighting in his shed, but he just kept taking the batteries to work to recharge them. :glee:

That's cheating but I like his style! Just checked the epoxy and it's stopped leaking as it's now got too viscous to freely flow/run/dribble. It's a nice 24°C in the test bay so should go off nicely...

[Wobblycogs]

Nice work Neil. Would have commented sooner but for some reason I've not been getting notifications of new posts.

Glad to hear the leaks have stopped.

[njhussey]

Just realised (when checking how it was curing in my lunch break) that I have made a total and utter f**k up on the epoxy....:hopelessness: I've only used half the hardner that I needed to. Now considering it's pretty simple maths to halve 800g of resin to get 400g of hardner my brain decided to stop pouring the hardner at 1000g.....WTF, did I decide that I liked the look of 1000g better than 1200g, was it too early in the morning for my brain to be working (was 7am when pouring so was up and out the house for 5.30am) or was it simply that I'm fecking stupid......!!!! I know what my money's on...

So looks like I'll have to try and scrape the epoxy off and start again as it's never going to fully cure. Out of desperation I'm putting it in the drying oven of our local contract painters over night (40°C - 50°C) to see what effect that has on it, however I'm not hopeful as it's been in a building that's about 24°C for the past 2 days and has only got to the stage where you can put a nail mark in it and it'll dissapear in 10 minutes. ARGGGGGGGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH......... ....:dejection:

[charlieuk]

the epoxy will never cure unfortunately it is the wrong type of chemical reaction you are best to strip it all off now clean up the mess and start a fresh. I made a similar mistake on my first surfboard i made! you will only do it once. I make sure i always zero the scales before adding the hardener as it saves simple mistakes. The other time this can happen is if you do not mix the two parts well enuff but sounds like you know were the problem came from.

[Wobblycogs]

We need a Homer Simpson "Doh!" emoticon for just this situation.

That's a real shame as it seemed to be going so well. It's going to be an pretty awful clean up job as well I'd reckon. I hope the drying oven works but I can't believe it will, your epoxy wouldn't achieve anywhere near it's maximum hardness anyway.

[njhussey]

the epoxy will never cure unfortunately it is the wrong type of chemical reaction you are best to strip it all off now clean up the mess and start a fresh. I made a similar mistake on my first surfboard i made! you will only do it once. I make sure i always zero the scales before adding the hardener as it saves simple mistakes. The other time this can happen is if you do not mix the two parts well enuff but sounds like you know were the problem came from.

To be honest I'm just hoping the oven makes it a bit harder so I can get it off easier...yes I'll only make this mistake once. Not an expensive one but just made lots of hard work for a stupid mistake. I mixed it really thoroughly in one container and then poured it into the ice cream tub and mixed it again well so I know it's not that.


We need a Homer Simpson "Doh!" emoticon for just this situation.

That's a real shame as it seemed to be going so well. It's going to be an pretty awful clean up job as well I'd reckon. I hope the drying oven works but I can't believe it will, your epoxy wouldn't achieve anywhere near it's maximum hardness anyway.

Yeah it's going to be a mess to clear up...oh well s**t happens. I'll leave the cleaning up until after the honeymoon, hopefully 10 days all inclusive in a Deluxe Penthouse apartment in Mauritius will chill me out...

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[gavztheouch]

I fancy giving this epoxy leveling technique a try. Can anyone recommend a good source and type of epoxy for the job.

[njhussey]

I fancy giving this epoxy leveling technique a try. Can anyone recommend a good source and type of epoxy for the job.

There are various ones:

West system 105 with the 209 slow hardner
Easy Composites
Reactive Resins Syntac EPAFD Slow Cure Epoxy Resin Pack
Infusion resin's

To name but 4. Most on here use Wests, Eddycurrent and I (although I've not mixed it correctly) have used Reactive resin and Jazz uses Infusions resins....take your pick!

[Clive S]

Neil Sorry about the cock up, it happens, its called a learning curve. I was going to comment on the mixing in your picture but now you are doing it again I will. You appear to have mixed it with a round rod I don't think that is good I think you need to do it with a flat piece of thin plywood or plastic as it will mix better. It says that on the WestSystem info about the correct way to mix and not to have the temp to high 20C is about right. Hope you don't mind me pointing this out. ..Clive

[EddyCurrent]

I came to this thread for sanctuary but it looks like you're having as many problems as I am, sorry to hear about the epoxy.

[JAZZCNC]

Yeah it's going to be a mess to clear up...oh well s**t happens. I'll leave the cleaning up until after the honeymoon, hopefully 10 days all inclusive in a Deluxe Penthouse apartment in Mauritius will chill me out...

Bollocks to that, you want a B&B in Whitby then spend what you was going to on that 5* place on a really nice CNC machine.!!. . . .You'd proabaly have change for an extension to the shed has well. . .:hysterical:

[njhussey]

Neil Sorry about the cock up, it happens, its called a learning curve. I was going to comment on the mixing in your picture but now you are doing it again I will. You appear to have mixed it with a round rod I don't think that is good I think you need to do it with a flat piece of thin plywood or plastic as it will mix better. It says that on the WestSystem info about the correct way to mix and not to have the temp to high 20C is about right. Hope you don't mind me pointing this out. ..Clive

Cheers Clive, yep learning curve all right. Just peed off with myself for making such a stupid error. I did mix the epoxy for at least 5 minutes very vigerously in the first container and once poured into the tub again for at least another 5 minutes before pouring it. I will use a flat piece of wood next time. That picture I took was after pouring it (from approx 2' above the tub) into the tub from the forst pot where most of the bubbles had been knocked out.


I came to this thread for sanctuary but it looks like you're having as many problems as I am, sorry to hear about the epoxy.

Cheers, I'll scrape it off and get some more epoxy and do it correctly this time! They're not problems, just small hurdles to get over...all part of the challenge!


Bollocks to that, you want a B&B in Whitby then spend what you was going to on that 5* place on a really nice CNC machine.!!. . . .You'd proabaly have change for an extension to the shed has well. . .:hysterical:

You saying my CNC machine isn't going to be really nice eh...eh?? :hysterical: Yeah for the price of the Honeymoon I could have just bought a really nice CNC machine, but where's the fun in that? Much rather make it myself...

[Wobblycogs]

Bollocks to that, you want a B&B in Whitby then spend what you was going to on that 5* place on a really nice CNC machine.!!. . . .You'd proabaly have change for an extension to the shed has well. . .:hysterical:

Only slightly cheaper than our honeymoon: a long weekend in Lincon. I don't remember getting to spend any more on the CNC though.

[GEOFFREY]

If Lincon is Lincoln its lovely, as are the natives. G.

[njhussey]

Had a quick look at the epoxy this morning, had a quick test peel and it should come off OK...still going to be messy mind....

[njhussey]

Well still not done anything on the frame yet (still doing jobs that were urgent before the wedding) but I've just ordered a new lathe...

12077

and milling machine...

12078

for my new work so I'll be able to do some milling and turning soon (end of May/beginning of June) :thumsup:

[EddyCurrent]

Neil,
Will you making a 'product' or will you be taking on any jobs as they come ?

[njhussey]

These are just for work for turning down the occasional hub/coupling or making the odd bespoke item or bits for test rigs etc. we outsource all of our machining to local companies. Most of the time these machines will be sat about doing nothing (read making parts for my cnc router!!) and I've been given the go ahead to cnc the milling m/c already...

[Clive S]

Neil
I purchased the WM18 mill and cnc'd it but I find there is a bit of backlash in the screws so I have decided to strip it down and fit ball screws when I get the time. I am happy with the mill in general though.:thumsup: ..Clive

[njhussey]

Clive, thats good to know that you're happy with yours. As I'm not paying for it I'll be fitting ballscrews from the off. Still deciding what steppers to go for but erring on NEMA 34's and 240V drivers...how easy was the Z to do?

[njhussey]

Moved the frame to my works workshop (or at least the area that's going to be the workshop once it's been tidied and sorted out) so I can start stripping off the epoxy I ballsed up...went and checked the epoxy this morning and it was hard??? WTF? Still going to strip it off and start again as I wouldn't trust it!!

The new milling machine and lathe are being delivered this week so once installed, stripped down, oiled/greased, adjusted and trued I'll be starting to make some brackets and other bits for my machine. Ordered another load of tools for the machines (boring heads/bars/indexable tools, angle plates/DTI's and base etc.) so will have every tool except the one I probably want!

I've found an old cast iron 24" square marking out table which will come in useful although it'll need the rust cleaning off part of it...and a 24" Mitutoyo vernier caliper, there's also a Mitutoyo vernier height gauge but the scale is really rusty so you can't see the graduations. Anyone got a good way of cleaning these items so they can be used again? I don't want to take a scotch pad or anything like that to them for fear of taking off the graduations or ruining the surface (although there might be some pitting on the surface plate) if I can help it?

Looking forward to re-starting work on the router as I've uses for it at work cutting out delrin/acetal rings for the couplings amongst other things...

[Wobblycogs]

I would think electrolysis would be your best bet. I think you'll get good results on the plate but my guess would be that the height gauge is toast as the markings will be too shallow.

[njhussey]

Pics of the rust...

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12479

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[Washout]

Hi Neil,
.
I've been thinking recently about a milling machine similar to the Warco you have ordered above (milling steel is potentially on the cards).
.
Are you going to do a build log, if you're converting to CNC? - I'd be most interested if so.
.
Cheers
.
Chris

[njhussey]

Hi Chris, yes ill do a build log. Might even do an unpacking/crating (or whatever) log and then a conversion log...depends on work commitments as to the timescale though!

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[njhussey]

http://img.tapatalk.com/d/14/05/28/ahagemap.jpg

http://img.tapatalk.com/d/14/05/28/u6y6emy3.jpg

Today I have been preparing the floor for the delivery of the machines on Friday...love my new job!!

[Washout]

Hi Neil,
.
A quick question (not critising your purchase), as I've been scouting about for milling machines with the same rough size as the Warco Major GH Mill. Does that machine use a round column or square dovetail?
.
Reason I ask is I have also been looking at this as a candidate AMADEAL - AMA30LV Milling Machine - MT3 - Metric | eBay (http://www.ebay.co.uk/itm/AMADEAL-AMA30LV-Milling-Machine-MT3-Metric-/360422555676) and it does use a dovetail, which from my limited knowledge is supposed to be more rigid?
.
Cheers
.
Chris

[Jonathan]

The column itself may or may not be more rigid - the rigidity gain comes from being able to move the mill head up and down, so you don't need to use the quill (much).

[njhussey]

I chose the round column as it had for us the best features for our needs...whether I'm correct or not remains to be seen!

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[Neale]

I recently bought the Warco VMC vertical mill. I did look at the round-column machines, but I had already had enough of a round-column machine with its inability to maintain accurate location as you raise and lower the head. A real pain if you are going from centre drill to large twist drill, and don't have enough quill travel to cope. The VMC is more like a "baby Bridgeport" although maybe without the latter's build quality... In the end, the things that swung me to the VMC were the dovetail bed rise/fall, and the fact that the drive motor hangs down rather than pointing upwards, and I have limited headroom in my garage (my wife wouldn't let me cut a clearance hole in the bedroom floor!) The ability to put on cut by moving the bed makes up a lot for the slight movement in the quill assembly, which can then be clamped tight and not touched during milling operations.

Be interested in your comments once the lathe is commissioned; been wondering about upgrading in that area but there are a number of choices, including similar machines from Chester and Axminster.

[njhussey]

The lathe and milling machine were delivered this morning, spent the afternoon siting them in the room. Not had a good look at them yet so can't pass comment just yet but they look like they'll be suitable for our needs.

Machines.
http://img.tapatalk.com/d/14/05/31/dave5apa.jpg

Tools etc.
http://img.tapatalk.com/d/14/05/31/u8y5ehag.jpg

In the room.
http://img.tapatalk.com/d/14/05/31/2e7yqyru.jpg

Mill.
http://img.tapatalk.com/d/14/05/31/gupu6u7e.jpg

Lathe.
http://img.tapatalk.com/d/14/05/31/aba4u3uz.jpg

Tools.
http://img.tapatalk.com/d/14/05/31/y5y9u8ut.jpg

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[Lee Roberts]

Hi Chris, yes ill do a build log. Might even do an unpacking/crating (or whatever) log and then a conversion log...depends on work commitments as to the timescale though!

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Cool look forward to that as we def need some mill conversion logs on here.

.Me

[GEOFFREY]

Hi Niel, I guess you think it's your birthday!!! Good luck. G.

[njhussey]

It is like having a birthday G as I didn't pay for them but have full used of them :)

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[Wobblycogs]

Nice looking bits of kit. Good amount of free space around them for chips as well :-)

[njhussey]

I'm just trying to persuade them to get a metal bandsaw...plenty of room there to make a mess!!

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[njhussey]

http://img.tapatalk.com/d/14/06/03/zebezydu.jpg

http://img.tapatalk.com/d/14/06/03/uvuvy7a8.jpg

Cleaned it up and fitted the quick release tool holder...what a great but of kit that is!

Done a test turn and quite impressed with it so far. Got to get the DRO reading correctly as it's showing half the actual value so will go through the manual tomorrow and get that sorted.

Tomorrow is setting up the milling machine and tidying up the area.

Sent from my Galaxy S5

[GEOFFREY]

If it reads half value on cross slide, could that be because one turn removes material from both sides if you get my drift? G.

[Jonathan]

could that be because one turn removes material from both sides if you get my drift? G.

Yep... most people like to think in diameters not radii when working on a lathe.

[njhussey]

Ok, to explain a bit more to see if I'm being thick (most probable) if I move the carriage handle (X axis) from 0 to 0.5 then the DRO shows 0.25. So is the DRO showing the actual amount moved (raduis) and the dial on the handle the amount taken off the piece (diameter)?

Sent from my Galaxy S5

[Jonathan]

Got it in one...

[Neale]

I'm used to a lathe where the cross-slide dial is calibrated in actual movement. Baffled the whatsits out of me the first time I used a machine calibrated in "diameter" instead - couldn't work out why I kept going through a measure/cut/measure/oh bugger cycle... Still, if it's anything like my mill with DRO, I can't remember when I actually read anything off a dial!
Is the lathe metric or imperial, and can you tell me how it manages screw-cutting of the opposite system - is there a 127T gear in there, or somesuch?

[njhussey]

I'm used to a lathe where the cross-slide dial is calibrated in actual movement. Baffled the whatsits out of me the first time I used a machine calibrated in "diameter" instead - couldn't work out why I kept going through a measure/cut/measure/oh bugger cycle... Still, if it's anything like my mill with DRO, I can't remember when I actually read anything off a dial!
Is the lathe metric or imperial, and can you tell me how it manages screw-cutting of the opposite system - is there a 127T gear in there, or somesuch?

I'm new to lathes (and milling machines) so still not sure about it all. All I thought was that the DRO would read the same as the handwheel dial, if the handwheel dial is showing diameter change and the DRO is showing raduis thyen all's good, however it looked to the naked eye that the cross slide was moving 1mm when the handwheel said 1mm but the DRO only said 0.5mm! I'lll set the DTI on it this morning and measure just to set my mind at rest.

Not tried screw cutting yet but it can apparently cut both metric (its a metric machine) and Imperial. Yes it has a 127 tooth gear plus a lot of others spare. I'll take some more photos of the gears it comes with and probably do a video of it cutting. Played with the speeds and feeds yesterday and got a nice finish so with more practice and reading up (I've got "The Amature's Lathe" and "Screwcutting in the Lathe" books so time for some bed time reading I think!) I think it's got a 32/85/100 combination currently fitted but not many of the gears are marked up (one more job on the list of things to do!)

Has anyone got any good recomendations for working out speeds and feeds, I'm sure I saw a post somewhere...will have a trawl at lunchtime.

[mekanik]

Hi Neil
My mate Ken has a lathe the same make with DRO, will have a word with him after and see how his reads, one thing i did notice the gearbox/headstock seems noisy on his so he doesn't use it @ high speed.
Mike

[njhussey]

Hi Mike, thanks for that. I'm messing about with the lathe and mill again today (currently cleaning and setting up the mill) so will put the DTI on the cross slide and see what it says with relation to the DRO and scale.

[njhussey]

Some numpty in the (presumably) Chinese factory has jammed the drill arbour shaft so tight in the spindle that no amount of smacking 7 bells of s**t out of the drawbar is getting it out. I've been hitting the nut so hard that I now can't get a 19mm spanner on it....getting seriously p****d off with it now.....

[Jonathan]

Some numpty in the (presumably) Chinese factory has jammed the drill arbour shaft so tight in the spindle that no amount of smacking 7 bells of s**t out of the drawbar is getting it out. I've been hitting the nut so hard that I now can't get a 19mm spanner on it....getting seriously p****d off with it now.....

You should be able to lower the quill and knock a drift through the slot in the spindle to release it?

[mekanik]

Hi Neil
Just checked Ken's machine and the DRO reads same as the dials,so you would put half the required amount you want to remove, there will probably be an option in the set up menu, I would imagine the "Y" axis should read the same as the dial reading. It's upto personal preference really, when working you can skim your OD Mike it and set your dial to suit, then use the DRO to put your cut on.
Tailstock/ remove the spindle and give it a coat of looking @ i think there should be a hole doing through into the tapered section, support the face of the spindle on your vice jaws and get a shaft down the hole and give it some welly.
Mike

[njhussey]

Thanks guys...

Got it out but the top is looking a bit worse for wear! Just installed the ER32 collet and put a 5.5mm 2 flute end mill in and made some (rough)chips...still got to set up the coolant system, put the wide coolant tray in and then it'll be all systems go!

http://img.tapatalk.com/d/14/06/03/pytebujy.jpg

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[njhussey]

Just bought some more resin....got to clean off the existing resin on the rails (it's now gone harder...but not hard enough). Will be starting to get the build going again as I've now got access to a lathe and milling machine!

[Wobblycogs]

Good luck getting the old resin off, how you planning on tackling it? I think a hot air gun would probably work but it'd definitely be an outside job.

[mekanik]

Hi Neil
As mentioned hot air gun probably the best option, if you start @ one end and break the bond, then soften a further section and try and get a scraper under it then hopefully you might be able to peel it off @ in one go.
Good luck and wear an organic vapor mask and some thick welding gloves.
Mike

[njhussey]

2 months ago it was peeling off in one piece as it was still soft.....it's now almost hard so might have to try a few things!!

[njhussey]

Put the new 125mm milling vice on the mill on Friday and set it square, quite pleased with the first attempt...


https://www.youtube.com/watch?v=M0bYmLa4EbU&feature=youtu.be

[njhussey]

Tried getting the epoxy off.....and it came off really easily! Pleasantly surprised to say the least.

http://img.tapatalk.com/d/14/06/16/8u7e8e6a.jpg

http://img.tapatalk.com/d/14/06/16/udu7e8yd.jpg

[njhussey]

New development on my build is that my work has just bought my router off me (well kit of parts so far) as they want to have one for cutting Delrin rings and other bits...I'll have use of it whenever I want (as well as the lathe and milling machine) so a bit of a win win situation for me as I can use this as a learning curve for building my own (probably larger one) later. Plus I'll be able to build this one in works time now legitimately :beer:

[JAZZCNC]

Plus I'll be able to build this one in works time now legitimately :beer:

Well make sure you put Servo's and all best gear on it so then if they go PoP you can buy it back cheap knowing it's got quality gear on it.:hysterical:

[njhussey]

Well make sure you put Servo's and all best gear on it so then if they go PoP you can buy it back cheap knowing it's got quality gear on it.:hysterical:

I was wondering whether to get a Nema 34 motor for the X axis as I'm going to drive both ballscrews with a belt. will I need one or will a Nema 23 3Nm one be ok or should I get another driver and stepper and do a slaved setup?

[JAZZCNC]

I was wondering whether to get a Nema 34 motor for the X axis as I'm going to drive both ballscrews with a belt. will I need one or will a Nema 23 3Nm one be ok or should I get another driver and stepper and do a slaved setup?

If your driving both with single motor then yes you'll need Nema34 about 6 to 8Nm but make sure you use high power drives for best performance.
My personal preferance is screws connected with belts but if you run slaved motors well within there capabiltys then you shouldn't have any troubles. The only thing I would recommend and will only Use with slaved setup's is Digital drives that have stall detect and provide a Fault signal which you can use to E-stop the system. If you do this then your safe with minimal risk of damage to screws when things go wrong.

What will the main use be.? and what size/pitchscrews are you using.?

[njhussey]

If your driving both with single motor then yes you'll need Nema34 about 6 to 8Nm but make sure you use high power drives for best performance.
My personal preferance is screws connected with belts but if you run slaved motors well within there capabiltys then you shouldn't have any troubles. The only thing I would recommend and will only Use with slaved setup's is Digital drives that have stall detect and provide a Fault signal which you can use to E-stop the system. If you do this then your safe with minimal risk of damage to screws when things go wrong.

What will the main use be.? and what size/pitchscrews are you using.?

I'm using RM1610 screws....main use will be plastics a bit of aluminium and possibly light cast iron work (spot facing cast iron couplings etc.) with a bit of balsa and lite ply cutting. I've got AM882's at the moment, they do up to 8.2A so a SY85STH118-6004B Nema 34 rated at 6A should be OK to drive?

[JAZZCNC]

I'm using RM1610 screws....main use will be plastics a bit of aluminium and possibly light cast iron work (spot facing cast iron couplings etc.) with a bit of balsa and lite ply cutting. I've got AM882's at the moment, they do up to 8.2A so a SY85STH118-6004B Nema 34 rated at 6A should be OK to drive?

Neil it's the 70-75Vdc limit of the drives that causes the problem with Nema34 motors. Larger motors need 100V+ to get decent speed out of them and that's why High power 240 Drives are best. Now with 10mm pitch screws and 75Vdc you'll get approx 8mtr/min of usable speed with a decent weight gantry. You'll possibly get higher speeds but they won't be reliable and could stall if pushed hard. That is more than enough for cutting most soft materials so again personally I'd go with single motor setup for reliabilty issues and to remove all doubt.!

That said AM882 are good drives for slaving has they have stall detect and can be used to stop system so either setup would work. You'll possibly get slightly higher rapid feeds from Twin motor setups as motors spin faster but that doesn't mean you'll get higher cutting feeds as the 34's tend to have more torque higher the RPM scale then drop off quickly.!

[njhussey]

Cheers Dean, I'll probably go single Nema 34 and 240V drive!!

[njhussey]

I presume that the below is some sort of tapping head? I've just dug it out of a box of large drill bits...anyone know exactly what it is and how it works?

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[EddyCurrent]

New development on my build is that my work has just bought my router off me (well kit of parts so far) as they want to have one for cutting Delrin rings and other bits...I'll have use of it whenever I want (as well as the lathe and milling machine) so a bit of a win win situation for me as I can use this as a learning curve for building my own (probably larger one) later. Plus I'll be able to build this one in works time now legitimately :beer:

Congratulations, great result.

[njhussey]

Congratulations, great result.

Cheers...got some more epoxy and some MDF for the weirs so just have to find some time to get the rest of the epoxy off the rails (its coming off really easily luckily) but there's other works stuff taking priority at the moment.

[njhussey]

Not done anything on this since the last update but have been specifying a Nema34 and 240V driver for the router along with the pulleys etc needed. Just bought for work an Axminster horizontal band saw http://www.axminster.co.uk/axminster-mcb1155hd-swivel-head-metal-cutting-bandsaw which seems to work OK.

13667

Gradually adding tools for making all sorts of stuff. I've got my small ARC welder and Pillar drill at work too so getting quite a nice little workshop together. only thing that would be better was if it was at my house instead of work but I do have access any time I like.

[EddyCurrent]

Gradually adding tools for making all sorts of stuff.

Tool collector or tool user ? that's the question. :joker:

[Jonathan]

That's the same saw as I have - they've just changed the colour scheme. Once I got the blade adjusted properly (i.e. not prone to fall off at awkward moments) it cuts well - nice and square.

Have you bought the motor & pulleys already? If not then did you calculate the required system or take an educated guess? If you post the parameters (mass of axis, length and diameter of ballscrews, desired feedrate etc) then I can verify...

[njhussey]

Tool collector or tool user ? that's the question. :joker:

Using them for work... :wink: making spacer rings for some of our products, making jigs and fixtures for pressing in and out bearings etc.

13668

Soon hope to be using them on the router (and mill conversion) but it keeps getting put back as more and more "one offs" keep coming in that I need to modify/make....not complaining as I'm being paid to play with the tools which makes a change from sitting at a desk all day long!!

[njhussey]

That's the same saw as I have - they've just changed the colour scheme. Once I got the blade adjusted properly (i.e. not prone to fall off at awkward moments) it cuts well - nice and square.

Have you bought the motor & pulleys already? If not then did you calculate the required system or take an educated guess? If you post the parameters (mass of axis, length and diameter of ballscrews, desired feedrate etc) then I can verify...

Hi Janathan, I've only done a couple of small test cuts on some 25mm rod to test it worked...will be checking the blade and giving everything a once over before it's used in earnest.

I'll have to dig out the drawing of the gantry (estimated) to work out the mass, ballscrews are 1610's length is 1300mm, feedrate I've not calculated (or did but can't find the calculations on the spread sheet) but it will be cuttng balsa wood, plastic and aluminium.

[Jonathan]

I'll have to dig out the drawing of the gantry (estimated) to work out the mass, ballscrews are 1610's length is 1300mm, feedrate I've not calculated (or did but can't find the calculations on the spread sheet) but it will be cuttng balsa wood, plastic and aluminium.

Just to be clear that's two ballscrews at 1300mm long, not one? By feedrate I meant what feedrate do you want, not expect, so for cutting those materials I'd say around 8-10m/min would be suitable. The mass doesn't have to be that accurate - within 10% is plenty good enough.

[njhussey]

Just to be clear that's two ballscrews at 1300mm long, not one? By feedrate I meant what feedrate do you want, not expect, so for cutting those materials I'd say around 8-10m/min would be suitable. The mass doesn't have to be that accurate - within 10% is plenty good enough.

Yes twin ballscrews 1300mm long! Going to drive it with one Nema 34 8.7Nm stepper (or 4.5 if I can get away with it) and a 2M2280N High voltage digital microstepping driver and a long belt :encouragement: 55kg weight springs to mind but I'm at work and the details are on my laptop at home.

[Jonathan]

Based on:

2 of RM1610-1300mm
55kg actuated mass


Assume:

10m/min feedrate
2m/s^2 acceleration
20T pulleys for 1:1 ratio, 30:N pulleys for 30:N ratio.
Cutting force of 25N
Not pre-loading ballscrews


Variables to select:

Motor size
Drive ratio


For the common 3Nm Nema 24 motors the corner speed is about 1000rpm, so lets start with 1:1 ratio and see if the torque calculated is low enough to use two of those motors. Using the script (posted here (http://www.mycncuk.com/threads/7355-What-size-servo-motor-do-I-need?highlight=matlab), and attached), the required torque from each motor is 0.47Nm. Up to their corner speed stepper motors output about 2/3rds of their holding torque, so 2Nm up to 1000rpm for the 3Nm motor, so since you only need 0.47Nm this system will definitely work up to 10m/min (1000rpm*10mm) plus a bit more since the torque will only drop below 0.47Nm at a fair bit more than 1000rpm, so you have a good factor of safety. You could even use 30:20T ratio and get 15m/min feedrate since the torque for these parameters is 0.78Nm, though you would need to used fixed-fixed bearings on the ballscrews to get the required critical speed.

One interesting thing to note is that if you use 30T pulleys instead of 20T, the torque required increases from 0.47Nm to 0.70Nm, so don't use bigger pulleys than necessary.

Lets try one motor driving both ballscrews:

Assume:


10m/min feedrate
2m/s^2 acceleration
20T pulleys for 1:1 ratio, 30:N pulleys for 30:N ratio.

One 20T pulley on each ballscrew
Two belts (length roughly 1/2 distance between ballscrews) with two 20T pulleys attached to motor.


Cutting force of 25N
Not pre-loading ballscrews


Since the system is symmetrical, we can model it as a single ballscrew with the length doubled and twice the pulley inertia. The calculated torque is 0.75Nm (or 1.09Nm with 30T pulleys). That's still within the ratings of the 3Nm motor... so no need for a Nema 34 motor (though it would clearly work, just be more expensive). If you want higher resolution, you could use 16:20 ratio (16T on motor) and the torque required is 0.55Nm.

My script also now calculates the ballscrew (nut, shaft & bearing) stiffness and the torsional stiffness of the belts. For example if we assume 100mm center distance, then for two motors the linear error due to belt compliance is 5.6um, compared to the error due to ballscrew stiffness of 0.7um. That's assuming worst case scenario - so machine operating with maximum acceleration and cutting force. If you use one motor, say the belts have about 700mm center distance then the belt stiffness goes down by a factor of 7, so it's now about the same as the torsional stiffness of the ballscrew. That sounds like a big difference, but you have to consider the stiffness of the whole system as clearly if the gantry is not terribly strong that will make a bigger difference than the belt stiffness (or lack of).

I've attached the scripts with your parameters entered for X - change the file extension from .txt to .m. The script runs in MATLAB, or GNU-octave which is free/open source and can be downloaded here (http://octave.sourceforge.net/). I encourage you to experiment with the numbers to get a feel for what parameters affect the torque requirements the most. You could put your numbers in for X and Z...

1367613677

[JAZZCNC]

Since the system is symmetrical, we can model it as a single ballscrew with the length doubled and twice the pulley inertia. The calculated torque is 0.75Nm (or 1.09Nm with 30T pulleys). That's still within the ratings of the 3Nm motor... so no need for a Nema 34 motor (though it would clearly work, just be more expensive). If you want higher resolution, you could use 16:20 ratio (16T on motor) and the torque required is 0.55Nm.

No sorry lovely calculations and all that but I can tell you from experience that 1 x 3Nm Nema 23 motor connected to 2 x screws with timing belts won't handle what will become 60Kg+ gantry and be reliable.!
Yes it will move it no problem and work but when the cutting gets hard or the speed and direction changes are fast it will struggle and the chances of lost steps makes it unreliable IME.
Either twin 23's or Single 34 is the way to go for this size/length and weight IMO.

[njhussey]

I calculated that I only needed one Nema 24 3Nm stepper for the twin X axis ballscrews but on thinking about it and listening to Dean I'll be going with a single Nema 34 on the X axis.....just to err on the safe side...after all it's not my money now so I'll be getting a 240V driver to go with the Nema 34 as well...:applause:

[irving2008]

I reckon they're both right :) Jonathan's calcs are ok if you are not microstepping cos then you have to derate the torque significantly not to lose steps, so Dean's answer is pragmatic in the likelihood you will be microstepping.

[Jonathan]

I reckon they're both right :) Jonathan's calcs are ok if you are not microstepping cos then you have to derate the torque significantly not to lose steps, so Dean's answer is pragmatic in the likelihood you will be microstepping.

Microstepping reduces the so called 'incremental torque' - i.e. the torque available to move from one microstep to the next and hold a microstepped position - the torque when the motor is moving continuously (i.e. the operating point I calculated) is the same regardless of microstepping. Also above low speeds stepper drivers switch to full stepping.

Personally I would still use two motors, but for other practical reasons - not due to the torque rating.

[Neale]

I've just about reached the stage on my machine where I have to decide one motor/twin belts or two motors. Sounds like the received wisdom is to go two motors. So, that means buying one more motor, another driver - but the old analogue ones I have at present are obsolete, so that will mean two new digital drivers, and, what's worse, ditching LinuxCNC and having to use Windows/Mach3 to be able to home two motors, and, probably, an external motion controller. Ho hum...

[njhussey]

I've just about reached the stage on my machine where I have to decide one motor/twin belts or two motors. Sounds like the received wisdom is to go two motors. So, that means buying one more motor, another driver - but the old analogue ones I have at present are obsolete, so that will mean two new digital drivers, and, what's worse, ditching LinuxCNC and having to use Windows/Mach3 to be able to home two motors, and, probably, an external motion controller. Ho hum...

I'm in a similar situation regarding the single vs two steppers, I can either buy another Nema 23 3Nm stepper and driver (but mine are the AM882 so I'd have to source from China or ebay) or a Nema 34 and 240V driver...decided on the Nema 34 for a bit of safety margin...

[JAZZCNC]

I calculated that I only needed one Nema 24 3Nm stepper for the twin X axis ballscrews but on thinking about it and listening to Dean I'll be going with a single Nema 34 on the X axis.....just to err on the safe side...after all it's not my money now so I'll be getting a 240V driver to go with the Nema 34 as well...:applause:

Ok well feel I've got to comment here about theses calculations or calculators. While I'm not saying the calculations are wrong what I am saying is that they are miss leading and not giving the full picture so sending people wrong. I've helped several people who have gone off them and been dissapointed with performance.!!

They don't and can't take into account all the factors that make up a working machine. They don't account for miss alignment or poor materials and how machine is designed and built or the affect this as on friction etc.
They don't account for the affects of resonance. They don't account for Cheap drives running on PC with poor pulses from a ropey parallel port.
They don't account for the DIY affect and the numerous things that can affect how machine performs.

All these things come into play and have a big affect on the overall performance and the calculators can never know these variables so IMO they are only to be used as a very rough guide.

This particular case is a prime example because while the Calculators says 1 x 3Nm Nema23 turning 2 x 1300mm screws connected with belts should all be hunkydory I can tell you with confidence you won't get anything like the performance that as been suggested. Yes it will move them but at much slower feed rate and acceleration than the calculator suggests to give a stable working machine.
So Neil believe me your Not Erring on the side of caution your doing what's is needed to get the level of performance your looking for.!!

Neale:

The single or Twin motor argumant falls down to ONE real differance.! . . How stable and accurate do you want your machine.?
If you wan't very stable with virtually no chance of screws losing sync even with cheap electronics then you need single motor/belts.

If you want to use twin screws then while they do work well they only do so provided certain things are correct.?
They are much more sensitive to motor tuning and need careful attention not to push too hard.
IME They work best and get best performance from them with Modern digital drives and External motion control cards which can provide nice clean pulses compared to ropey parallel port.
IMO it's crucial they have some form of stall detect or Error signal on the drives so if one motor stalls or drive fails the system shuts down. I won't build a twin screw machine without this option and Those that have built using twins motors and had this happen at speed will tell you how scary the big potential for damage.

I build more machines using Twin motors than single motors because it's easier but will ONLY do so provided I can build like the above. I Only build using Motion control cards and Digital drives and still leave a comfortable margin on tuning for best reliabilty and safety.
I never have any issues with twin screws building this way but it comes with a cost. Single motor and belts while more messy and involved is cheaper and more forgiving with lesser electronics.
I never truely trust twin screws not to stall or twist up the machine in some way if pushing hard for exteneded periods and I'm always mindfull while using and setting up. Where has I have complete trust in single motor setup and it never enters my head in use no matter how hard I push, no matter how long I push it for.!!

Both work.!!

[EddyCurrent]

M = Misalignment
Q = Materials quality
D = Design and build
F = Friction etc.
R = Effects of resonance.
C = Cheap drives running on PC
P = Ropey parallel port.
Y = DIY effect
O = other miscelaneous effects

For each of the above assign a value between 0 and 1; 1 = 'perfect' or negligible, 0 = 'total shite'

JazzFactor = M*Q*D*F*R*C*P*Y*O

(Note: if any value=0 then JazzFactor=0 hence idea=total shite so don't even bother.


Actual calculation = theoretical calculation * JazzFactor

Example:

theoretical torque = 0.75Nm

JazzFactor = (0.9 * 0.95 * 0.9 * 0.99 * 0.9 * 0.95 * 0.9 * 0.85 * 0.85)

actual torque = 0.75 * 0.42

actual torque = 0.32 Nm :joker: :joker: :joker:

[njhussey]

Well I dusted off the frame this afternoon and took the last of the epoxy off. It's actually set really hard so I could have used it after all....but better safe than sorry I'm going to re - do it from scratch. 10 mins with a hammer and chisel (screwdriver) and and angle grinder with flapper disc and it's back to bare metal. Going to cut mdf sides this time and seal the gaps/edges/joins with silicone sealant. Got to do a bit more proper work now this afternoon on the lathe but hope to get the moat done tomorrow.

http://tapatalk.imageshack.com/v2/14/12/17/12f7ca265517cd97fb34e3930f223d61.jpg

http://tapatalk.imageshack.com/v2/14/12/17/1f70db44941b5b4244473cf53a8a543f.jpg

Video showing the hardness of the set Epoxy...


http://youtu.be/cwzTb2aPNnU

[njhussey]

Only managed 1/2 hour on this today but cut the MDF for the moat. Tomorrow I'll glue it together and seal it, thinking of sticking it to the steel with silicone sealant which will also act as a sealant to stop (hopefully) any leaks as I don't want a repeat of last time where despite my best efforts (obviously not good enough) I had leaks at some joins.

If I can get it together and sealed then I might go for a pour so it starts to set over the weekend. Whatever happens I'll not be rushing this....lesson has been learnt from last time :)

14133

[EddyCurrent]

Neil,
I trust you read silyavski's thread about his epoxy method ?

[njhussey]

Neil,
I trust you read silyavski's thread about his epoxy method ?
With the metal strips?

[Clive S]

Only managed 1/2 hour on this today but cut the MDF for the moat. Tomorrow I'll glue it together and seal it, thinking of sticking it to the steel with silicone sealant which will also act as a sealant to stop (hopefully) any leaks as I don't want a repeat of last time where despite my best efforts (obviously not good enough) I had leaks at some joins.

If I can get it together and sealed then I might go for a pour so it starts to set over the weekend. Whatever happens I'll not be rushing this....lesson has been learnt from last time :)

http://www.mycncuk.com/attachment.php?attachmentid=14133&stc=1Here was my effort flashing the heat gun across gets rid of a small bubbles: ..Clive

[EddyCurrent]

With the metal strips?

Well maybe not, this is the thread, also read a few pages earlier; http://www.mycncuk.com/threads/6619-Quite-an-Unusual-one?p=63914#post63914

[njhussey]

Well maybe not, this is the thread, also read a few pages earlier; http://www.mycncuk.com/threads/6619-Quite-an-Unusual-one?p=63914#post63914

Yeah I've read it....my pour went OK apart from a couple of leaks which I cured and me not having the correct ratio. I got no shrinkage and the epoxy was level all round (measured with a straight edge and level) so I'm going to go as I did before. Mine is only 1300mm long so no where near the length of Boyan's which I think is where alot of his problems came from.

[njhussey]

Finished the moat today, another day of only 1/2 hour to work on the machine. Still ill not be rushing!!!

http://tapatalk.imageshack.com/v2/14/12/19/f99086c37931bcd6af3fe081d921eb9b.jpg

Built it with tabs so that I can lift it off and replace it easily after running a bead of sealant under/round it to seal the gaps. Started gluing the mdf with superglue but ended up using no-nails...will put some oil on the MDF first so the epoxy doesnt stick (as much) to it.

[EddyCurrent]

...will put some oil on the MDF first so the epoxy doesnt stick (as much) to it.

Would parcel tape work instead of oil ?

Taking no chances this time eh !

[njhussey]

Yes, i was going to use that...Trouble is there's some oil already on it so the parcel tape won't stick...

Nope not taking any chances...going to triple check everything!!! ;)

[Clive S]

Neil I used the Wests System and found it easier to weigh out the two parts with a digital scale rather than by volume and mixing with a flat paddle (strip of ply etc) if this helps. Good luck. ..Clive

[njhussey]

Neil I used the Wests System and found it easier to weigh out the two parts with a digital scale rather than by volume and mixing with a flat paddle (strip of ply etc) if this helps. Good luck. ..Clive

Yes the reactive resins is done by weight, twice as much epoxy to harder I seem to remember....will write it down in big numbers so I can't get it wrong!!! I've got some proper mixing sticks this time...

[m.marino]

Do you have access to a vacuum pump? IF so, you can put the well mixed resin in an over sized container and degas that way (a sealed 50 gallon drum can act as a chamber if the pump can handle the volume). That gets rid of pretty much all gas in the resin which will make for a much better pour and no worry over bubbles. The issue is getting access or having a vacuum pump that can handle the volume.

Michael

[Clive S]

Or a drum that can take a vacuum .. Clive

[Neale]

Just how important is this degassing anyway? I stirred my resin vigorously, let it settle for a few minutes, then poured. I didn't even use the "pour through a small hole" technique. There were some bubbles in the resin as poured, but I paddled a bit of lolly stick back and forth to encourage the resin to find its own level, and also to remove bubbles. The few that were left were very easy to deal with once the resin was hard. It's not something that I'm going to spend much time worrying about when I come to epoxy the gantry rail mountings. For reference, that was using 500g resin/250g hardener on a similar size machine.

[njhussey]

Ive not got access to a vacuum pump but I'm not too concerned about it as before I did the two pot mixing and pouring through a hole from about 12" and there were very few bubbles. Those that did form were dealt with by a piece of welding wire (didn't have a cocktail stick at work) which as Neale said also helped it find its level.

[njhussey]

Cleaned the rails with thinners and used a tack rag to get all rubbish off then put silicone sealant down and put the oiled moat back on. Now waiting for the sealant to go off overnight so I can trim it back inside and then tomorrow am I'll do the epoxy mix and pour. That way it'll have 10 days over Xmas to set!

http://tapatalk.imageshack.com/v2/14/12/22/4e48d277cc435f73710bcd822bb3d65f.jpg

http://tapatalk.imageshack.com/v2/14/12/22/6022b39636547a1f0bf879e124627a0b.jpg

[njhussey]

Well......epoxy pour is done....triple weighed everything and double checked...

Leveled the frame on the floor...

http://tapatalk.imageshack.com/v2/14/12/23/6dc8c17984a27b49bba9f137bf1ec5c1.jpg

Weighed the epoxy out...

http://tapatalk.imageshack.com/v2/14/12/23/845e0ca34794fd9e515b63381f42e41a.jpg

Weighed the harder out...

http://tapatalk.imageshack.com/v2/14/12/23/eb7404b7c1635c6d17c3ff1b60bef689.jpg

Mixed it in a cut down 2 litre milk carton first...

http://tapatalk.imageshack.com/v2/14/12/23/2cc47d4ffbeb5531578a6bbbe084b775.jpg

Then transfered to a flatter container with a 7mm (ish) hole drilled in a bottom corner with tape over...poured it from a couple of feet high to mix it as it was transferring

http://tapatalk.imageshack.com/v2/14/12/23/fc395063748a20677a65926d845e0ad7.jpg

Stirred it some more then poured it in the moat with fingers crossed for no leaks....

http://tapatalk.imageshack.com/v2/14/12/23/c70b890e064c5d32e6bd843daa8de143.jpg

http://tapatalk.imageshack.com/v2/14/12/23/63ad41be405f5d14385665fad18b05f0.jpg

There are a few bubbles but a quick swizz with a lollipop stick and they went. There are a few microscropic bubbles but I'm not too worried about them...

http://tapatalk.imageshack.com/v2/14/12/23/c30cc74ad5617fbb7890e2d58320d95f.jpg

http://tapatalk.imageshack.com/v2/14/12/23/db0ceb3fad93938a93a62a7512be6bcd.jpg

There are 3 leaks, one from a corner joint on the bridge, and 2 where there must be a gap under the wood. Happy with that as they were stopped with some paper towel and parcel tape.

You could see the epoxy going across the bridge where it was leveling itself off so it obviously works!

Clive, I used a flat stirring stick this time [emoji6]

[njhussey]

Nearly all bubbles have gone, leaks have been stopped so now I can stop crawling round on the floor...

http://tapatalk.imageshack.com/v2/14/12/23/23b7e71d62f24df526e847eeb0d257a4.jpg

http://tapatalk.imageshack.com/v2/14/12/23/62097cf7712522ed3eb0443afa2b7d51.jpg

[Clive S]

Neil Looking good as you know I just flashed the surface with the hot air gun and the small bubbles just disappeared like magic. Happy Xmas. ..Clive

[njhussey]

Neil Looking good as you know I just flashed the surface with the hot air gun and the small bubbles just disappeared like magic. Happy Xmas. ..Clive

Clive, I was going to use my blowtorch but there were only a couple of bubbles so i popped them with the lollipop stick, there were so few microscopic ones that I didn't bother....thosse seem to have floated up to the surface and popped over lunchtime.

Merry Christmas and a Happy New Year to you Clive.

[Clive S]

Neil

Blowtorch as in naked flame!! Hot air gun no naked flame. Happy new year as well. ..Clive

[njhussey]

Neil

Blowtorch as in naked flame!! Hot air gun no naked flame. Happy new year as well. ..Clive

Sorry yes hot air gun.....I still call them blowtorches :stupid:

[EddyCurrent]

Hooray ! it's done, the build will speed up now that hurdle is out of the way, looks good and a plus for Reactive Resins

[njhussey]

Hooray ! it's done, the build will speed up now that hurdle is out of the way, looks good and a plus for Reactive Resins
Cheers, yes the build will speed up now....looking forward to cracking on with this in the new year!!

[Wobblycogs]

Wow, that's one heck of a nice job you've done there. I will most certainly be asking for guidance when it's my turn to run the epoxy gauntlet.

[njhussey]

Cheers Graham, as with everything the key is in the preparation.

I was looking at the leaks before I left work this afternoon and all the leaks are actually where the mdf was joined. Next time I'll have more time and use wood glue and then seal the joints with sealant. Will also use more silicone sealant under the moat as it's easy to get off the metal.

[njhussey]

Sat down after Christmas dinner [emoji490] [emoji486] [emoji485] and I really want to pop into work to see how the epoxy is doing.....there's no hope for me I know!

I have decided to use the 20mm thick Ali plate (don't know the grade) as a bed for it. I'll buy the bits for the Y axis gantry and the Z axis in eco cast, especially as work are paying for it [emoji6] ill get it on order when I get back to work so I can crack on ASAP.

http://tapatalk.imageshack.com/v2/14/12/25/1497bcf3c3974076d6a7696c73d05bd8.jpg

[njhussey]

Just popped in to work as I was round the corner recycling some of the Xmas paper, boxes etc. It's set nice and hard, shiny and smooth. It's going to be a pain getting the moat off and the silicone sealant but overall I'm happy with it.

http://tapatalk.imageshack.com/v2/14/12/28/cad7077216ebc83d3d6739102f418c23.jpg

http://tapatalk.imageshack.com/v2/14/12/28/1a3fc1cabbd3a970b321290f8d44a831.jpg

http://tapatalk.imageshack.com/v2/14/12/28/fed81ae2b8318106e56f275c09c9bcde.jpg

http://tapatalk.imageshack.com/v2/14/12/28/3dbbe9f5feda1ba60db29697e9509360.jpg

[mitchejc]

Great job, looks like that epoxy came out perfectly! I've had some good luck removing sealer with a hard wire brush.

[njhussey]

Ok so the MDF moat is off, wasn't too bad to get off in the end.....but in hindsight I'd make sure the MDF was not oily (been hanging around in the machine shop for a couple of months) and put brown parcel tape on it as it doesn't stick to it and comes off cleanly. I'd also put parcel tape on the steel where the moat was going so that the silicone came off easier too. It's nothing that a bit of elbow grease won't sort. I've found the best tool to scrape off the MDF is an indexable lathe tool...not scraped it fully in the below picture

http://tapatalk.imageshack.com/v2/15/01/05/379069e8c53cb142af476506a3876bfc.jpg

Here you can see the meniscus, the epoxy is about 7mm thick.

http://tapatalk.imageshack.com/v2/15/01/05/d70bdb6423d4a086b97fa34909bf3f4b.jpg

Here you can see the difference between the wrong ratio mix of epoxy and the correct...the incorrect is on the right and although you probably can't see it the epoxy is a bit grainy looking and opaque whilst the correctly mixed epoxy is far more translucent and shiny...

http://tapatalk.imageshack.com/v2/15/01/05/55e7fc09d15322b48580d516d19e150d.jpg

[njhussey]

One rail is done and the other is half done. More MDF stuck to the epoxy on this side so it's taking longer to get off...

http://tapatalk.imageshack.com/v2/15/01/05/9a00d024f7b8519689c6411ab47fddbd.jpg

http://tapatalk.imageshack.com/v2/15/01/05/0c74427d15daf8a6e4fc89a90577f6fd.jpg

http://tapatalk.imageshack.com/v2/15/01/05/02154731cbdbc4ff01ec7bcfdbeeaf7a.jpg

http://tapatalk.imageshack.com/v2/15/01/05/43465661e9f27fce7ef4a72c464c55ef.jpg

[njhussey]

Quick video of me getting a section of the MDF and silicone sealant off today.

Also filing down the meniscus on both sides.


http://youtu.be/pnQsH_rOY1E

[Lee Roberts]

If its not to late in the clean up game, get yourself down to the nearest UPVC setup, ask them for a bottle of PVC cleaner, you want the clear stuff not the "jiff like" stuff, it's great I use it for everything it's designed to desolve silicon sealant and it dose so like magic, it doesn't turn it into a pasty mess like you would think it just somehow frees the silly up enough that you can just peel it off.

Seriously, get some anyway it removes all sorts really well. I use ISOPROPYL for some stuff but the PVC cleaner works great for allot of things, £2.50 here for a one 1ltr bottle.

.Me

[njhussey]

Cheers Lee, I'll have a look at that!

[njhussey]

Finished off the last of the cleaning up of the epoxy this afternoon.

Worked out how I'm going to get the rails square. We have a 24" Mitoyo caliper which just happens to be the correct length for the spacing of the rails. I've drilled and tapped one hole (after shortening one rail to the correct length) on one rail as the base reference and ill clamp down the other ends using the caliper as a measuring stick. I'm then going to use the milling machine to mill a piece of 10mm Ali plate down one long edge and both ends, then ill drill mounting holes for the carriages and using squares off the reference face of the carriages make sure all is square before tightening down the plate. I can then use this to slide up and down to get the rails parallel and then mark and drill the holes.

Anyone see any issues with this method?

http://tapatalk.imageshack.com/v2/15/01/06/f65779beaf9cef52b66191adf1db8a75.jpg

http://tapatalk.imageshack.com/v2/15/01/06/73f844e1111105ebc48418d64764feb6.jpg

http://tapatalk.imageshack.com/v2/15/01/06/5deb5b499f4843ff87c7fd7377cf33df.jpg

[Neale]

Depends on whether you have a gantry to use as a gauge? I had built the structure of my gantry in advance for this purpose, so I bolted down one rail along the box section centre line, placed the second rail on its box section, and attached the carriages to use to align the rails. I think, in essence, you are doing the same thing but you will then pick off the rail spacing dimension to finalise the gantry. Hiwin recommend aligning the rail against a machined step but where this is not possible you align the second rail from the first. My only reservation is how you guarantee the straightness of the first rail but I think you can finally adjust this by test cutting. I hope so, anyway!

[EddyCurrent]

Looks a nice epoxy job.
To fit the first rail I clamped a good wide straight edge on top of the beam then butted the Hiwin rail up to it, like Neale said about the machined step. Then I mounted the gantry and used the bearings themselves to line the second rail, just nipping the bolts up slightly. Before fully tightening the second rail down I put the straight edge up to it to make sure there were no kinks. After that I also checked the distrance between them at points along the length just too make sure they were parallel.

[njhussey]

Depends on whether you have a gantry to use as a gauge? I had built the structure of my gantry in advance for this purpose, so I bolted down one rail along the box section centre line, placed the second rail on its box section, and attached the carriages to use to align the rails. I think, in essence, you are doing the same thing but you will then pick off the rail spacing dimension to finalise the gantry. Hiwin recommend aligning the rail against a machined step but where this is not possible you align the second rail from the first. My only reservation is how you guarantee the straightness of the first rail but I think you can finally adjust this by test cutting. I hope so, anyway!


Looks a nice epoxy job.
To fit the first rail I clamped a good wide straight edge on top of the beam then butted the Hiwin rail up to it, like Neale said about the machined step. Then I mounted the gantry and used the bearings themselves to line the second rail, just nipping the bolts up slightly. Before fully tightening the second rail down I put the straight edge up to it to make sure there were no kinks. After that I also checked the distrance between them at points along the length just too make sure they were parallel.

Thanks guys.....

I'm going to do a similar thing to both of you. I don't have a good straight edge that I can butt the rail up to so I'm going to use the first rail as a reference and use the dummy gantry to get the second rail square to the first. Regarding striaghtness of the rails I might look at using a small laser pointer that I have to shine along the length to check for any bend in the rail, not sure if this will work but don't see why not in principle?

Got some more cutting discs (and G clamps to clamp the rails) on the way in to work this morning so I can cut the second rail to length. Looks like it's going to be lots of drilling and tapping today, hope there's not too much proper work to get in the way of doing this...!

[JAZZCNC]

But how do you know the first rail is striaght.???

I wouldn't waste any time setting the second rail without the gantry on the machine. Set the master rail straight and parallel to frame then run set slave rail using gantry running up n down feeling your way along as you tighten up the rail. . . Feel for binding is a very good guide in setting up.!

[EddyCurrent]

Got some more cutting discs (and G clamps to clamp the rails) on the way in to work this morning so I can cut the second rail to length.

I rarely use metal cutting discs so I bought these after reading the description, I was amazed how good they are; quick, little mess, cuts rails like butter. !00 times better than the thicker type.

http://www.toolstation.com/shop/p39737

[njhussey]

I rarely use metal cutting discs so I bought these after reading the description, I was amazed how good they are; quick, little mess, cuts rails like butter. !00 times better than the thicker type.

http://www.toolstation.com/shop/p39737

I've got some 1mm thick ones, as you say they cut through the rails like a hot knife through butter. I've got the Y & Z axis rails to seperate (curently two rails 1100mm long with 4 blocks on each soon to be split.....) but now thinking of making the Y axis rails longer to get the carriage spacing wider. Just re-drawing it to see if I can get away with slightly less Z axis travel.

[njhussey]

But how do you know the first rail is striaght.???

I wouldn't waste any time setting the second rail without the gantry on the machine. Set the master rail straight and parallel to frame then run set slave rail using gantry running up n down feeling your way along as you tighten up the rail. . . Feel for binding is a very good guide in setting up.!


Dean, how do I make sure one rail is straight without buying a proper striaght edge? My frame is not straight enough to align the first rail, or at least I don't think so as it's just plain 100 x 50 x 4mm steel, with any sort of accuracy?

I was thinking of getting some of my 10mm thick Ali and using the milling machine machine as much as I can down one edge and then turn it round and then using my edge finder set it parallel again and machine the rest to give a straight edge. Would this do?

[Clive S]

Dean, how do I make sure one rail is straight without buying a proper striaght edge? My frame is not straight enough to align the first rail, or at least I don't think so as it's just plain 100 x 50 x 4mm steel, with any sort of accuracy?

I was thinking of getting some of my 10mm thick Ali and using the milling machine machine as much as I can down one edge and then turn it round and then using my edge finder set it parallel again and machine the rest to give a straight edge. Would this do?How about using some fishing line stretched very taut along the length. ..Clive

[njhussey]

How about using some fishing line stretched very taut along the length. ..Clive

Wouldn't that be a little flexible? Plus I've got an end stop on one end so can't wrap it round the rail, would have to accurately drill a hole through the steel.

Just looking at a Veritas straight edge http://www.axminster.co.uk/veritas-steel-straight-edge which I could clamp to the rail to keep straight?

[Clive S]

Wouldn't that be a little flexible? Plus I've got an end stop on one end so can't wrap it round the rail, would have to accurately drill a hole through the steel.

Just looking at a Veritas straight edge http://www.axminster.co.uk/veritas-steel-straight-edge which I could clamp to the rail to keep straight?You could clamp the line to the rail with a spacer say 1mm between the rail and line then do the same at the other end with spacer. With the line tight you can then measure with a feeler along the length after fixing one end first. ..Clive

[Neale]

As Jazz said, sliding a carriage along is a pretty sensitive test of whether or not the rail is fairly straight - you quickly feel the graunching sensation if it isn't! My design uses an aluminium block with two carriages bolted to it (gantry then bolts to these later) and having two carriages fixed in line is even more sensitive. No way am I going to buy a 1.8m straightedge for alignment purposes.

Just bolting it down by eye (I loosely bolted one end of mine, then wiggled it a bit to let it find its own line) is probably good enough for a first pass, with a sanity check of running the carriage up and down. It's not going to be many thou' out, I reckon. I then set the second rail to this, knowing that it's probably not absolutely straight but good enough to work, and will then fine-tune it by cutting test pieces once the machine is in a state to actually cut something. It's another example of the "you can't build it accurately enough but you can tweak it afterwards" home-workshop approach...

[njhussey]

Well as I said earlier I've a low power laser (that i was going to use on the mill for alignment) that I've played with. Taped it to a DTI magnetic stand and aligned it so it shone along the rail. You can tell any high spots as the line gets brighter. The spots are dust/dirt. Will tweak this tomorrow but the rail looks straight enough. The carriages certainly slide easily with no binding, I'll try 2 bolted on a piece of Ali tomorrow after machining a reference edge to line the carriages up to.

http://tapatalk.imageshack.com/v2/15/01/07/028bdfeb3206d15e9e0ec29694a69032.jpg

http://tapatalk.imageshack.com/v2/15/01/07/ae38f6a0649b894e95ae43521e48d924.jpg

http://tapatalk.imageshack.com/v2/15/01/07/99b9e4694bb81b499909255f9925ab75.jpg

[Lee Roberts]

Neil, fix a nice plate to both bearings on your choice of master rail, then pop a clock dial on via a mag base featuring a long reach arm/boom to get to the other rail with the clock, then traverse the master rail via the plate and bearings dialing in your second rail as you go.

Ideally you would want to do this with out the bearings and plate and so just moving the mag base along the master.

That's how I always do it for the machines I build from wood [emoji23] .

.Me

[njhussey]

I've decided to cut the 20mm piece of Ali I currently have to the correct width for the bed which will leave me a 100mm (ish) wide strip 1000mm long (ish) which I can use for mounting blocks. I'll cut a piece 200mm long and machine a carriage block...

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Then after attaching the carriages on the master rail I'll move it up and down and clamp the rail ready to drill.

I've made a small drill guide to go in the rail so the drill bit is kept at 90° (or as near as damn)

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I've put a piece of 10mm Ali plate on the bed and moved my Pillar Drill on to it to drill the holes, a bit like below...

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Should make drilling easier (but slower) and I hope not to snap any more drill bits as I snapped one in an end hole on the rail :hopelessness::hopelessness:

[EddyCurrent]

Neil, It's obviously best to drill the holes spot on but if they are tapped at an angle it's wasted effort, I like your drill guide so maybe a similar thing is reguired for the tap or maybe you could just open out the drill guide hole slightly.

[Jonathan]

Sliding carriages along the rail gives some indication of the straightness, but very little indication of the twist. Fortunately for us these rails have very low co-efficients of friction, but when it comes to aligning them this makes small errors in straightness harder to detect as they don't produce much force.

Using an indicator mounted on one rail carriage to measure and fix the distance between the rails is good once you've got one rail straight. If you do if before then, you'll just copy the error - so if one rail is banna shaped the other one will be the same banna shape. To be fair that's still better than having a banna and some other fruit...

From a practical point of view, if you've got the rails aligned well enough that the bearings run smoothly then the bearings should last a long time, so it's arguably OK to use but you will need to have realistic expectations of the accuracy.

[njhussey]

Neil, It's obviously best to drill the holes spot on but if they are tapped at an angle it's wasted effort, I like your drill guide so maybe a similar thing is reguired for the tap or maybe you could just open out the drill guide hole slightly.

Funny you should say that....I've just made a tap guide as I had that very thought. Will be tapping them by hand, shant be impatient and use a drill!

[EddyCurrent]

Sliding carriages along the rail gives some indication of the straightness, but very little indication of the twist.

He's right, I forgot about that. Neil just go and buy a straight edge :concern: I remember putting one across the top of my rail bearing beams to find they were leaning out slightly. This was due to the welding process but the epoxy job brought it right again. I did however put the straight edge across the top of my rails once fitted to ensure they were still level. Obviously if they are out and you bolt down the gantry cross member there will be a lot of stress put on the Hiwin bearings.

[njhussey]

Sliding carriages along the rail gives some indication of the straightness, but very little indication of the twist. Fortunately for us these rails have very low co-efficients of friction, but when it comes to aligning them this makes small errors in straightness harder to detect as they don't produce much force.

Using an indicator mounted on one rail carriage to measure and fix the distance between the rails is good once you've got one rail straight. If you do if before then, you'll just copy the error - so if one rail is banna shaped the other one will be the same banna shape. To be fair that's still better than having a banna and some other fruit...

From a practical point of view, if you've got the rails aligned well enough that the bearings run smoothly then the bearings should last a long time, so it's arguably OK to use but you will need to have realistic expectations of the accuracy.

Surely the twist will be sorted when the rail is bolted tightly down, that's assuming that the epoxy is perfectly flat of course?

I'm going to use the sliding carriage method to drill and tap the holes, there is a clearance of 0.5mm either side of the bolt in the rail hole so plenty of room for adjustment. When I get the tooling/eco plates I'll be machining a reference edge to mount the carriages to the bottom piece of Ali, then the gantry will have a reference edge to mount the carriage plates to and thus I hope the gantry will be straight/perpendicular/parallel etc. etc. so that when I bolt the carriages to it the second rail will be referenced from the first which will be as straight as I can get it without having a machined reference edge in the epoxy to go on.....if that makes sense?

I think I'll get a straight edge, that will help with twist and straightness....plus the above and it should all be as acurate as it's possible for a bodger like me to get :thumsup:

[JAZZCNC]

Surely the twist will be sorted when the rail is bolted tightly down, that's assuming that the epoxy is perfectly flat of course?

Gezzzz People have too much trust and expectations of epoxy.? You can't beat checking so buy or make a straight edge to confirm if you really think you need that level of accurecy in a router.!!!


When I get the tooling/eco plates I'll be machining a reference edge to mount the carriages to the bottom piece of Ali

Why waste money on Eco-cast if your going to mill the ground surface away.? . . . The whole point is the accurecy of the ground plate and no matter how careful you won't mill to same level as grinding gives.!

What I do with ground plate when I need a ref edge is mill pockets on the ref line and insert aluminium dowels 3mm proud of surface. Then I machine half the dowels away to the plate surface leaving me machined ref edge without disturbing the ground plate.
Like this.
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[mekanik]

Have to agree with Dean, can't see the point in going to all trouble of designing your machine, getting feedback from the experienced members and then making a horses arse of aligning the rails at the last hurdle.
No offense intended.
Regards
Mike

[njhussey]

None taken Mike, im all ears with regards to how its done. That's why I keep saying how I think I'm going to do things then listening to the advice given by the more experienced members.

The last thing I want to do is make a horses arse of aligning the rails having got this far :)

[mekanik]

Glad about that Neil
I assume you have tried the reference edge of your rails when placed face to face? can you get a feeler between them, not that that is a definative test as they could both be bent the same. I know the squares and straight edges are a substantial investment that doesn't seem justified on possibly building a couple of machines,are you near any engineering or tech colleges that have this sort of gear a suitable deposit might get you the loan of some suitable kit.
Good luck with the build
Regards
Mike

[njhussey]

Mike, I'm ordering a straight edge and a couple of engineers squares tomorrow along with the tooling plate.

I'll try the feeler gauge tomorrow and see how that is but I do remember when I first got them that I had them together every which way and couldn't see any light between the rails.

[mekanik]

That sounds promising if you cant get a feeler gauge between the reference edges you could use the rail as a straight edge. have a look @ Silyavski's post before you buy any kit he did a lot of researching looking for straight edges and squares, you want the stuff that's made to a decent spec can't remember the BS number of hand but it's there in his thread.
Regards
Mike

[JAZZCNC]

so it's arguably OK to use but you will need to have realistic expectations of the accuracy.

Bingo he's Hit the nail on the head.! . . . . . . . People are getting silly on this forum regards the level accuracy they are trying achieve or THINK they are achieving with what is essentially Cave man tools in engineering terms.

Be realistic and remember it's a router based machine that will probably spend most of it's time cutting materials that have high variations of in-stabilty that far excede the accuracy machine can cut too.!

If you take your time to align the rails with sensible means IE: Clive S suggestion of taught wire along with feeling of bearings etc you'll be very close if not spot on for the use of the machine.
Yes rail alignment error will affect performance and live span of the rails but with care and patience the level of error will be so small to make little difference at DIY levels. Even in small/medium scale production enviroment it will take good few years to have any affect on wear if care is taken on setting up and alignment.
Just throw them on and you'll pay the price but with careful setup and sensible attention to detail you won't go wrong.!! . . . . Stop over thinking it and take sensible precations with checking straightness/twist along with feeling your way and you'll be fine.!! . . CRACK ON

[mitchejc]

Neil your build is looking great. I bet you can smell the wood chips already :-)

Please take what I’m about to say with a huge pinch of salt as I just fitted my first rails ever on my first build, so no real experience here but I’m putting it out there hopefully to get corrected or affermed. Look, I don’t know, maybe my expectations of final accuracy is just low or I got very lucky with the batch of 15mm Hiwin rails I received but those reference edges are as straight as Charles Bronson. Keep in mind my build is relatively small so I guess on longer rails it might be a totally different story. Few of us has the right equipment but I believe Jazz’s way with machining the dowels is the best approach assuming the mill you cut it on is accurate over that distance. I’ve seen builds where straight edges are clamped to the rail before drilling but I don’t think a straight edge is still straight after clamping it to something that’s potentially not straight?

I did not use a clamped straight edge for my reference rail. To ensure I didn’t bend it out of shape I clamped it to the epoxy base, drilled, tapped and fastened the ends and then repeated the process by moving the clamps for the rest of the holes always making sure I only drilled next to a clamp if that makes sense. On my rails the holes are 4.5mm and the bolts are 4mm which leaves a huge amount of adjustment as far as these things go assuming one does not stuff up drilling and tapping the holes.

For drilling I used a method proposed on here, I think Silyavski : Using the rail holes as reference, I took a 4.5 mm drill and drilled though the epoxy to the point where it made a good tapper dimple on the steel below and then drilled the rest of the hole with a 3.3mm drill for the tapping. That 3.3mm drill has no choice but to run to the centre of the dimple. Touch wood, I’ve done 40 something holes so far and not one out of centre so it appears this method is working really well. The important thing is that there is no binding whatsoever when you put the bolt in otherwise it will push the rail out of straight or best case you won’t any room for adjustment later. The steel on the inside of these rails where the holes are, are softer than I imagined so I guess the outsides where the bearing run are only case hardened. Not ideal but I’m totally prepared to enlarge the hole in the rail a little to ensure the bolt is not touching sides due to bad tapping or drilling the tap hole at a slight angle. I then used my straight edge and a feeler gauge (ok, it’s not really a straight edge but it’s a good quality stainless steel ruler and I know the one edge is relatively good) to check that the rail. I believe I have enough adjustment in the rail holes to fine tune it somewhere in the future if I get a real straight edge but I’m pretty confident it’s already better than my expectations of accuracy.
I then used my gantry after aligning it perpendicular to my first rail etc to align the second rail and then repeated the clamping drilling, tapping and fastening exercise on that side. As pointed out by Jonathan, I realise that these rails are quite slippery and it would require a huge force to actually get them to bind, but I did the best I could to move it around while aligning the second rail to feel for any sort of friction and I’m very happy with how smooth it’s running.
Even with this potentially dodge method I followed it still took me more a full day to get my x rails on so no quick wins here :cheerful:

Best of luck with fitting your rails.

[njhussey]

Well I've stopped buggering about and started drilling and tapping the first (reference rail) rail. I put the two reference sides of the rails together , as suggested, and I couldn't get a 1 thou feeler gauge to even start to go between them.

I've drilled and tapped about 7 holes so far with my set up as below and all the holes are nicely central with approx 1/2mm each side of the hole so plenty of room for any adjustment if needed.

http://tapatalk.imageshack.com/v2/15/01/09/79ce369d23e3c8d959c9e9e993f30e81.jpg

http://tapatalk.imageshack.com/v2/15/01/09/6fbf096fb31b11fe42de9798492109ca.jpg

http://tapatalk.imageshack.com/v2/15/01/09/0d29efdaac56827d9162bd159e91c2c7.jpg

Tooling plate is on order but will be 5-6 days [emoji17] and now going to order a straight edge from the same place as Silyavski in Germany to make sure that there isn't any (or negligible) twist in the rails.

Thanks for all the comments and suggestions guys!

[njhussey]

Quick vid showing the drilling with the guide in place, I've not showed setting up to drill a hole as I'm sure that's pretty self explanatory...saying that so is drilling the hole...oh well :whistle:

The pillar drill is a bit old and knackered and I think could do with a little TLC....


https://www.youtube.com/watch?v=HBGuVm6FQKs

[njhussey]

Did a bit of shopping on Friday and it turned up today :eagerness: I bought a 1200mm Veritas straight edge, a couple of 6" engineers squares and 4 100mm G cramps.

Placing the straight edge against the rail there was a bow in the middle of the rail of about 3 thou so I loosened all the master x rail bolts and clamped (lightly) the straight edge to the rail in 6 places. I then tightened the bolts checking with a feeler that there was no gap between the reference side of the rail and the straight edge. Once this was done I placed the straight edge on the reference side of the rail and tried the feeler gauge again. It was the same all the way down with no gaps so I'm happy with that. I'm going to clamp (lightly) the straight edge to the rail again and then one by one take out the M5 socket cap heads and threadlock them in. This should give me my master reference X rail to set the second X axis rail from.

14399

I wanted to see if there was/how much twist there is in the rails. Placing the straight edge across the two rails on top of the carriages I tried to get a feeler gauge underneath the edge and couldn't. Shone a light from the other side and couldn't see a thing so it looks like the epoxy has done it's job in finding the level. Again I'm happy with that!

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14401

Waiting on my Tooling plate to come before I square the second X axis rail so I'm just making drawings so I know where I'm drilling holes, machining pockets for steppers ballscrew housings etc, what size belts and pulleys to get etc. etc.

[Jonathan]

Surely the twist will be sorted when the rail is bolted tightly down, that's assuming that the epoxy is perfectly flat of course?

Quite likely yes - but how much force will bending the bearing to 'flat' impose upon it? The answer is a lot, since the stiffness of these bearings is still very high in the rolling direction. It also depends on how stiff the gantry is and how wide it is - something has to bend. A fairly high force wont make much difference to how smoothly the bearings roll, since as I mentioned in the last post their co-efficient of friction is very low. It will still shorten the life of the bearings though.

It's different with round rail bearings - clearly they have zero stiffness in the rolling direction, so angular misalignment doesn't affect the force of the bearings (within reason).

If you look in the datasheet for the rails and bearings you'll find specifications for the maximum linear and angular misalignment. These are based on getting the rated lifetime out of the bearings, so if you exceed it by a little, the bearings just wont last as long. Though on a home machine it might still outlive you!


I wanted to see if there was/how much twist there is in the rails. Placing the straight edge across the two rails on top of the carriages I tried to get a feeler gauge underneath the edge and couldn't. Shone a light from the other side and couldn't see a thing so it looks like the epoxy has done it's job in finding the level. Again I'm happy with that!

That's a good indication that they're close, but since you've got the straight edge you might as well measure it carefully. The issue with what you just did is it's hard to measure very small angles and you don't get a reading for what the angle actually is. Instead you need to do something like in my build log - stick the dial indicator on one of the bearings and mount the straight edge parallel to the rail, but some distance (say 200mm) horizontally away from it. Make the indicator touch the straight edge, with it's movement perpendicular to the surface. That will convert the angular reading into a linear reading and amplify it. You don't need to worry too much about getting the straight edge level, as if you plot the readings on a graph that will just make a linear error which you can subtract.

Just out of interest, how much did the straight edge cost?

[njhussey]

Quite likely yes - but how much force will bending the bearing to 'flat' impose upon it? The answer is a lot, since the stiffness of these bearings is still very high in the rolling direction. It also depends on how stiff the gantry is and how wide it is - something has to bend. A fairly high force wont make much difference to how smoothly the bearings roll, since as I mentioned in the last post their co-efficient of friction is very low. It will still shorten the life of the bearings though.

It's different with round rail bearings - clearly they have zero stiffness in the rolling direction, so angular misalignment doesn't affect the force of the bearings (within reason).

If you look in the datasheet for the rails and bearings you'll find specifications for the maximum linear and angular misalignment. These are based on getting the rated lifetime out of the bearings, so if you exceed it by a little, the bearings just wont last as long. Though on a home machine it might still outlive you!



That's a good indication that they're close, but since you've got the straight edge you might as well measure it carefully. The issue with what you just did is it's hard to measure very small angles and you don't get a reading for what the angle actually is. Instead you need to do something like in my build log - stick the dial indicator on one of the bearings and mount the straight edge parallel to the rail, but some distance (say 200mm) horizontally away from it. Make the indicator touch the straight edge, with it's movement perpendicular to the surface. That will convert the angular reading into a linear reading and amplify it. You don't need to worry too much about getting the straight edge level, as if you plot the readings on a graph that will just make a linear error which you can subtract.

Just out of interest, how much did the straight edge cost?

I'm not too worried about the life of the bearings, as you say I'm sure it will outlive me and for what it's being used for. I will measure it though out of interest as I have the straight edge ...

The straight edge was from Axminster http://www.axminster.co.uk/veritas-aluminium-straight-edge it's got a claimed accuracy of 0.075mm over the 1270mm length which although not super accurate is more than good enough I think for my purposes.

[Neale]

Picking up Jonathan's comment re stiffness in roll and manufacturer's tolerance...

HiWin 20mm rails have a maximum permitted height difference of 0.130mm with 500mm rail spacing. That corresponds to a difference of 0.013mm across that 50mm or so bearing block. Don't know about you, but that's about a quarter of my thinnest feeler - and that's the maximum allowable tolerance. As for stiffness - and I don't recommend you do this at home as I only did it by accident - my gantry structure probably weighs around 30kg, and I managed to leave it hanging while only attached to the carriage at one end. It probably dropped by no more than 25mm or so. I hate to think of the abuse of the pair of bearing blocks taking the weight, but what's done is done. I shall be reporting on my experiments with epoxy (i.e. mistakes and how I've tried to correct them) elsewhere when I'm actually happy with the results, but in simple terms, it's a lot easier to get the rails level than to remove twist. The main reason to get the rails level (given that you will take out minor variations by machining the spoil board anyway) is that with, say, a 1000mm rail spacing, the max rail height difference spec only allow a height difference of about 0.26mm (10 thou). That's not too difficult with epoxy, and I would expect rather better with just a bit of care. But twist? As long as it is constant, then the gantry to bearing block joint can be shimmed/adjusted to suit but you only need a tiny amount of varying twist to go way out of spec. I'm still trying to get mine somewhere near acceptable. I'm using a sensitive level (0.02mm/m readings) to check.

It would be easy to say that the problem is that I'm chasing irrelevant numbers with tools that are working at their limit, except that a trial bolt-down of rails with gantry mounted gave clear signs of graunching bearings even when I was happy with levels. Suck-it-and-see tells me that there's something wrong.

[njhussey]

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These are the NSK specs on running parallelism....seems in theory I have about 16 microns for my 800mm spaced rails to play with....to be honest I think you can keep chasing numbers till you're red in the face and for a router that's going to be used for wood and plastics mostly with some aluminium then I'm not going to get my knickers in a twist about it.

I'm going to do a quick test as Jonathan did (I'm intreagued now) and then once the gantry is made bolt it to the carriages and see what they sound and feel like.

[EddyCurrent]

I bet you wonder how you ever managed without a straight edge now :glee:

[njhussey]

Picked up the cut tooling plate just now....gantry build can start next week though first got to design and build a pantograph arm for putting in M6 UNC bolts and grease nipples into 1000 units we're currently assembling for a contract....oh, that's after I've finished machining a custom unit that's just been ordered. Work keeps getting in the way of playing!

14438

[njhussey]

Been drawing up the gantry in Geomagic 3D program today. Getting there, so far all the holes etc. line up!

14477

[EddyCurrent]

Looks good software on their website, can't wait to get stuck into that aluminium plate eh !

[njhussey]

Looks good software on their website, can't wait to get stuck into that aluminium plate eh !
Yeah its good software, we just got the Mill package that goes with it so should be able to draw parts and then mill them on the router or the next project which is CNCing the mill...

No I can't wait to get stuck in. Taking my time making sure it can be put together etc...[emoji3]

[EddyCurrent]

I found that it could only be designed and drawn up to point, the rest was sorted out as it happened.

[njhussey]

I found that it could only be designed and drawn up to point, the rest was sorted out as it happened.
I think that's what's going to happen here. The major holes etc will be drawn and then the fine adjustments and fitting will be done ad hoc.

Hope to get it all machined up by mid next week in between the other bits of work I have to do.

[njhussey]

Been working on the Z axis today, not done it all by any means as work keeps flipping geting in the way...

14480

14481

Not drawn the plates that the Y axis Carriages attach to yet (simple so won't take long) ot the Z axis Stepper plate which is going to have a pocket for the stepper milled into it with slots so the belt can be tensioned. The Z carriages and rails are just blocks drawn to the correct dimensions but with no detail, couldn't be bothered and couldn't see the parts in the online library to download but not looked too hard!

[JAZZCNC]

Put some material back on that front plate it will help with resonance. You only need to remove what you need to remove for the screw to clear.

[njhussey]

Put some material back on that front plate it will help with resonance. You only need to remove what you need to remove for the screw to clear.
Cheers Dean, I'll alter that tomorrow.

Quick question. I was going to use the DIY spindle that I've made but seeing as I'm not paying ill probably get a water cooled spindle and VFD, now is it worth getting the 2kw or 3kw one and which VFD (without going overboard on cost that is!) to get and any recommendations where to get them?

[Wobblycogs]

Keep in mind this info is a bit over a year out of date but I got a 2.2kW water cooled spindle and VFD from Chai for £216 ex VAT. There were places that were a little cheaper but as I was getting other parts from Chai it made sense to get them all together. I also found a load of suppliers on ebay that I wouldn't touch with a barge pole, YMMV, worth a google pre-purchase though.

[njhussey]

Front plate re-drawn with smaller pocket in it...

14484

[njhussey]

Dean, you did realise that the front plate is a 40mm thick plate? The pocket is 20.6mm deep so 19.4mm still remains in the middle.

Anyhow....managed to get another few minutes on the CAD....put together the assembly and surprisingly it all fits together!

14485

[njhussey]

One last pic before home time.....the Z axis on the gantry....

14486

[njhussey]

Not sure if this will work but I've just created a 3D PDF of the router which I'll try to attach...I know I've not done the 50x25 cross members yet...or put things like steppers, ballscrews etc but it's just the basic frame and gantry.

14494

[mekanik]

Opens OK in Foxit Reader
Mike

[Wobblycogs]

Well it worked for me. I didn't know PDF's could do that, I must investigate more. The rendering is as good as you get in something like SolidWorks. The design is looking good and really coming on a pace now.

[njhussey]

Opens OK in Foxit Reader
Mike

Cheers Mike...


Well it worked for me. I didn't know PDF's could do that, I must investigate more. The rendering is as good as you get in something like SolidWorks.

I've not played with the clours and rendering yet, will do if I get time. We've bought an add on that means you can make animations, can't wait to install that and have a play with it (bought it to do work animations for our new web site that we're currently designing)


] The design is looking good and really coming on a pace now.

Again cheers, just doing the dimensioned drawings for the pieces now so I can start the machining...looking forward to that!

[njhussey]

Set up a straight edge parallel to the master rail 300mm away and put a DTI on a carriage and moved it up and down the rail. There's about 0.25mm of twist/dip mostly near the rear of the machine.

Only conclusion I can accurately draw however is that my DTI is too cheap as it moves all over the place i.e. doesn't return to zero after going up and down a few times...need a better quality DTI....

[njhussey]

Did a bit of drawing as well today...

http://tapatalk.imageshack.com/v2/15/01/26/b4dba2f0cdc056a39d40027ba3999032.jpg

[Neale]

Set up a straight edge parallel to the master rail 300mm away and put a DTI on a carriage and moved it up and down the rail. There's about 0.25mm of twist/dip mostly near the rear of the machine.


Any thoughts on what might have caused this? I'm still experimenting with my machine and epoxy but it's been too cold in my garage lately to pour any more. Took the old epoxy off this afternoon and shall shortly be trying a slightly different technique.

[njhussey]

Any thoughts on what might have caused this? I'm still experimenting with my machine and epoxy but it's been too cold in my garage lately to pour any more. Took the old epoxy off this afternoon and shall shortly be trying a slightly different technique.
I'm going to check the rail for bow/dip tomorrow with the straight edge to see if it's that. If it is then ill shim the rail where it's twisted if I can.

[njhussey]

Looking at the rail today I put the straight edge on the rail and tried the feeler. There's a dip at both ends (last 6 inch) of the rail so ill have to shim that before carrying on much further :(

Not done much else on the machining as been making a tapping arm today...

http://tapatalk.imageshack.com/v2/15/01/28/81c1fc0bf210bc595ce86cd1bdfc9bba.jpg

[njhussey]

Needed some 20mm aluminium for a clamp for the pantograph arm I'm making at work so put the big plate I've got on a table and used the Evolution circular saw to cut the plate to size for the bed. The 100mm strip cut off will be used for blocks for mounting the ballscrew mounts on etc...

http://tapatalk.imageshack.com/v2/15/02/03/636f412cf9b9dec43e5e15777a7c7978.jpg

[EddyCurrent]

How well does that saw cut ? I used a sabre saw last time but you can't get a good straight line with it. I have a Hitachi saw similar to the one in your photo, I wonder if an evolution blade will fit ?

[njhussey]

I was sceptical about the adverts for it but it cut a 1" steel bar and slowly munched through the Ali plate, my steering left a bit to be desired at the end but it's not critical as it's going on the base and all the blocks will be milled to size. Next time I'll use a fence to guide the saw rather than my eye ;)

I believe that Evolution have made the blade hole diameter different from mist blades so it can't fit any other saw....but don't quote me on that. I remember reading it somewhere, a forum or somewhere like that.

[Wobblycogs]

I cut 10mm aluminium plate on my mitre saw using a regular TCT cross-cut wood blade, just sprayed on a bit of WD40 before the cut. It was similar to cutting a very hard, close grain, wood except the aluminium was a little sticky feeling. I think a rip cutting blade would be better as it wouldn't stick so much as it cut. Anyway, I'd happily make cuts with a regular circular saw if didn't have a better option to hand, not sure I'd even go to the expense of getting a special blade unless I was going to do a lot of cuts.

[JAZZCNC]

I've been cutting 20mm Ali plate dry for years with and TCT thin kerf cross cut blade in table saw that is so knackerd it won't cut Oak without smoking the workshop but yet munches Ali no problem. Absolute must that you wear full face mask and cover arms and neck as the chips are scorching hot.!

[longy]

yes tct blades cut ali with no problems as long as you take your time. Used one of these in the chop saw to ali http://www.ebay.co.uk/itm/250mm-Circular-Saw-Blade-30mm-Bore-80-Teeth-Aluminium-Alloy-Wood-Negative-Rake-/381042611179?pt=UK_Hand_Tools_Equipment&hash=item58b7e8d3eb at £9.50 I was a bit sceptical but it cut OK no good on wood as it burns and does not cut so well, like Dean said just fills the shop with smoke.

[njhussey]

Been doing machining in between making a tapping/pantograph arm....arm's finished (minus cleaning and painting) and mounted on the wall ready for the next batch of units to come through the works.

14639

Can't wait to get cracking on the rest of the machining and assembling the gantry.

Must start the contorl panel shortly too so will be looking through the threads and then asking lots of questions about PSU's etc......:stupid:

[njhussey]

Got a few bits to assemble now, can't find the bolts I got for it so going to have to go out this afternoon and get some more :hopelessness:

14642

14643

14641

The Z Axis plates are still to be done as are the Y carriage mounts.

Should be able to get the second X Axis rail aligned using the gantry soon :beer:

[njhussey]

Some more photos...

14646 14647 14648 14649 14650 14651 14652

[njhussey]

Squared up the X Axis carriage with the DTI...


http://youtu.be/RmBQaucbpiQ

Found out that the frame that started out nice and square over a year ago (when I welded it) isn't actually square anymore....there is 2 or 3mm of rail sticking out the left side when the right side (depending on your viewpoint of course) is right at the end.....(edit: just measured it and the rail, which is not bolted down yet, had moved back a bit!!) nothing drastic, just annoying.....

http://tapatalk.imageshack.com/v2/15/02/10/70e7d2cbc3bb24fd6819c3aabe23e4d9.jpg

[njhussey]

Second rail is squared up and drilled, tapped and bolted down. I can't notice any tight spits but as Jonathan said you've got to really get them out of line to notice any tight spots.

Tapped the holes on the top of the gantry and used the straight edge and DTI to get it as near straight as possible.


https://www.youtube.com/watch?v=6Jug438XMd4&list=UUX_ImztPc6hUkKDfklSSdBA

Just going to do the same for the bottom rail....

Edit: The DTI is running along the front if the aluminum plate not the rail itself...

Painting the frame tomorrow...

[Jonathan]

In the video is your indicator tip running along the other rail - not the rail you're pushing the bearing along? It's hard to see in the video... you will want to indicate from one rail to the other to get them parallel (ish).

Edit: Just realised, looks like you're indicating against the straight edge?

[njhussey]

Yes indicating along the front of the top piece of Ali. Checked it with a straight edge, feeler and light first. Will indicate off the second rail once the gantry is together.

The Ali top, bottom and front pieces were CNC machined to size in one go (I sent them out to someone with a bigger table than me....cheating I know but more accurate than making a jig and moving the plate along to machine a bit at a time :whistle:) and clamped together (not the front plate) so I'm hoping that once it's put together it won't need too much tweaking to get them parallel (ish) :whistle:

[njhussey]

Did a bit of painting this afternoon for an hour....

14664

[njhussey]

More machining today, got a couple of new M4 spiral flute taps which make light work of the tapping for the 15mm THK rails on the front plate.

http://tapatalk.imageshack.com/v2/15/02/16/c0c679a6543da455e957cd58b859208d.jpg

[njhussey]

Set the Z axis rails parallel by referencing off the plate side for the master rail then referencing the secondary rail off the master...

http://tapatalk.imageshack.com/v2/15/02/18/c8f7f5c761b3868ba06ef8077f863791.jpg

[EddyCurrent]

Flying along now and looking good.

[njhussey]

Flying along now and looking good.
Cheers...going to order a couple of CSIMO IP-M's and some Nema 34 4&8Nm steppers, 240v N series drivers today for the mill conversion (that's next to do) one's for the X axis on this...

[njhussey]

Had to "tweak" some machining on the Z axis stepper mount and also the Z axis back plate...will also have to machine a small pocket out of the Z axis front plate for the ballnut mount as it's not quite (0.6mm) right...

http://tapatalk.imageshack.com/v2/15/02/18/47ab5d10024c8a9c182aa0f967312c24.jpg

http://tapatalk.imageshack.com/v2/15/02/18/af653cff967342ccc790ec8f6c9f19bf.jpg

It's going together quite nicely...so far!

http://tapatalk.imageshack.com/v2/15/02/18/e6bc412b819ac2187ba6075b725633fc.jpg

[njhussey]

OK so Z axis is together now, couldn't resist a little test with a cordless drill :toot: The machining on the ballscrew is not 100%, there's a wobble on the drill but it's not too bad and I'll be able to live with it.


https://www.youtube.com/watch?v=wDKnJQskjh4&list=UUX_ImztPc6hUkKDfklSSdBA

For the eagle eyed among you you'll notice that there are 8 holes for the ballnut holder....erm not much to say apart from oops :stupid:

[Neale]

Does the cordless drill have step/dir inputs to drive directly from Mach3?

[njhussey]

Does the cordless drill have step/dir inputs to drive directly from Mach3?
Good old brain to finger inputs only...

[Neale]

Sometimes the best way! Take those damned computers out of the loop...

[njhussey]

I'm a child of the 70's.....so going to use it like an etch a sketch!

[Neale]

The original MPG! Now, there's another idea for a CNC router enhancement...

[njhussey]

Just a bit more painting last thing this afternoon is all I managed...

http://tapatalk.imageshack.com/v2/15/02/19/0ac3bff9f3c9fe801f192f88cd207a68.jpg

Did do a bit of research on the electronics today so will post up what I think I need when I've finished researching.

[EddyCurrent]

If you don't paint it now you'll never paint it :thumsup:

[njhussey]

If you don't paint it now you'll never paint it :thumsup:
That was my thinking...

[IanS1]

Coming along nicely Neil. Can't wait to see this one finished.

[njhussey]

Coming along nicely Neil. Can't wait to see this one finished.

Cheers Ian, I can't wait either...it's only been about 4 years in the making!!

[njhussey]

Quick assemble of the gantry this morning. Got the holes for the X axis ballnut holders to machine later on the Y axis endplates, then some pads to make for the ballscrew ends...

http://tapatalk.imageshack.com/v2/15/02/23/ee34afc2c376bc77ebffc6f44a98c9c0.jpg

Thinking about it I'll make the pads first and then see if I need to machine back the Y axis end plates...

[njhussey]

Made some BK & BF mounting pads....only took a photo of one but you get the gist....

http://tapatalk.imageshack.com/v2/15/02/23/a5bfc5c670d7f2c01782008c316465b9.jpg

http://tapatalk.imageshack.com/v2/15/02/23/b13c704f5cdf9d2526c99d49c4c62c66.jpg

[EddyCurrent]

I dont see any means of fine adjustment, unless the holes are oversize ?

[njhussey]

The holes are oversize so there's 1mm of adjustment movement. I'll be clamping the blocks whilst adjusting them so the final adjustments needed should be very small....thats the plan anyway!

[EddyCurrent]

The holes are oversize so there's 1mm of adjustment movement. I'll be clamping the blocks whilst adjusting them so the final adjustments needed should be very small....thats the plan anyway!

You'll probably need shims behind them too, those cut from empty Guinness cans are a great thickness for this :whistle:

[njhussey]

I'll have to machine down the pads as they're too deep, wouldn't bet against still having to shim something though.....a great excuse to get some beer in :eagerness:

[njhussey]

Well disappointingly I only managed a few diet coke cans at work for shims...clamped one ballscrew to the side and ran the ballnut up and down a few times. The ballscrew has a good wobble to it where it's either bent at the ends or the machining is crap.

http://tapatalk.imageshack.com/v2/15/02/25/481213f4038c10bf7e01888eeabfc119.jpg

The drive end ballnut pad needed 1.2mm machining off and the NDE needed 1.2mm of shims...

One of the things that I didn't think through properly with regards to assembly was the X axis ballnut holders. I got the aluminium ones that are small and compact and they fasten from the underside/reverse so on my design I'd gave to take the gantry end plate off to remove them which is far from ideal. I've ordered a couple if MGD16 ballnut holders that can be fastened from the outside. I'll probably have to machine back the base so it is the same height as the current ballnut holders but that's no biggie with the mill.

http://tapatalk.imageshack.com/v2/15/02/25/6d45b32137d6d8728f577526c26554bd.jpg

Link below is flycutting the DE mount to remove the 1.2mm needed to make it fit.


https://www.youtube.com/watch?v=k7BDi5H78rE&feature=youtu.be

Couple of pics cutting the Ali plate with the bandsaw and then squaring and machining to size the ballnut plates.

http://tapatalk.imageshack.com/v2/15/02/25/918c3168d6deb09632998f4beb45cae3.jpg

http://tapatalk.imageshack.com/v2/15/02/25/55ded9c0ee54a3c7cb9a322e2b86288c.jpg

I ordered 2 x CSIMO IP-M controllers and 4 x Nema 34 8.7Nm steppers and 4 x 240V HV stepper drivers today...looking forward to those coming. 3 steppers and drivers and one IP-M are for CNCing the WARCO Major GH mill.

Tomorrow's ordering will be PSU components and belts and pulleys...

[njhussey]

14751

Got some belts and pulleys today, didn't get them from Belting online or anyone like that as our local company we use for bearings etc. Gloucester bearings (Hayley) were so much cheaper for the pulleys and a bit cheaper for the 2525 belt...

7 off 20 tooth pilot bored pinions - P20-5M-15F £1.73 each

1 off 2525-5M-15mm HTD belt £14.85

2 off 265-5M-15mm HTD belt £4.31

I realise that the pinions aren't pilot bored like the ones from belting online but I was going to have to drill them out to the correct size for the ballscrew ends and stepper shafts on the lathe anyway.

[njhussey]

Got another package just now....it's like Christmas :yahoo:

Opened the box from Gary @ Zapp...

14753

CSMIO....

14755 14756

Showing it's size against a Nema23 stepper and AM882

14754

Kinco 230V Driver

14757147581475914760

Nema34 8.7Nm motor...(4 off)

1476214761

Showing the difference between a Nema23 and 34...

147651476714766

Drilling the pulleys...2x8mm, 4x10mm & 1x12mm

1476414763

[routercnc]

Getting close now Neil !

A cracking set of bits, should run nicely with those fitted.

[njhussey]

Getting close now Neil !

A cracking set of bits, should run nicely with those fitted.
Cheers!! Only one Nema34 is going on this....it'll be on the X axis driving the twin ballscrews. The other 3 will be going on the mill conversion ill be doing next...hoping to do more tomorrow but work is getting in the way!

[Lee Roberts]

That's a smaller nema34 of the bunch, colossal aren't they !

.Me

[njhussey]

OK so I'm going to order a new 600 x 600 x 300 cabinet and parts for my electrical panel, can someone check to see if I need anything else...if I've missed something:

600 x 600 x 300 - 1 off
20A door isolator (presume NC contacts so contact is broken when door's opened?) - 1 off
Emergency stop panel mount button with NC contacts - 1 off
Green push button panel mount, NO contacts - 1 off
Red push button panel mount, NC contacts - 1 off
Green LED panel mount light - 1 off
Top hat slotted DIN rail - 2m length
2.5mm grey DIN terminals (gettting 50 off)
2.5mm Earth terminals (getting 25)
bootlace ferrules 0.75mm, 1mm, 1.5mm (100 of each)
Crimping tool - 1 off
25x40 slotted cable trunking - 2m

I've got 2 x 120mm 24V cooling fans which I'll get filters for which I'll mount on the sides
I've got 1.5mm^2 4 core shielded cable (about 25m) for connecting the steppers to the drivers
Was thinking of getting 3 core 0.75mm^2 shielded for the limit switches, is this the correct cable to get?
What other cable will I need?

I'll be ordering parts for my PSU, so far looking atthe below components. Can someone please comment on them please to make sure I'm going in the right direction?

Calcs:
Toroidal voltage V(DC)=1.4xV(AC), so 70/1.4=50V
Question, I've read that if yout supply is greater than 230V then the voltage output is higher which would be a bit too near the max 80V the AM882's can take if there's back EMF from the steppers on deceleration? So would it be better to get a 2x24V transformer as linked below?

Current: I've 3x4.2A steppers (Z axis, Y axis and a future 4th axix) plus a 6A Nema34 making 18.6A but 60% is 11.16 so call it 12A? So transformer needs to be 12Ax50V=600VA sdo nearest is 625VA.

Capacitors: C(uF)= 100000xCurrent/Voltage = 17,143 so a 22,000uF 100V capacitor should do....any ideas where to get an economical one or are multiple smaller ones better?

Bleed resistor, I'm either going to use one switched through a relay or is it not worth bothering with? I'm more inclined to use one as I'd rather discharge safely than just leave the steppers to drain the caps. My calcs are: R=5000000/2200=227Ohm, rated at V^2/(2xR)=10.8 Watts. Any suggestions on what to get here?



Toroidal Transformer - http://www.airlinktransformers.com/chassis_mounting_toroidal_transformers/chassis_mounting_toroidal_transformers_standard_ra nge/CM0625224/

Rectifier - http://www.rapidonline.com/electronic-components/kbpc3502-35a-200v-bridge-rect-mb352-47-3226

I'm sure there's more that I've forgotten but I'm sure that someone will suggest it (hope so...)

[Wobblycogs]

The advice I was given was to get a 2x24V transformer and having measured the output and input voltage I'd definitely say that's the best advice. The power to my house at least tends to be a few volts over 230V so a 2x25V transformer + back EMF would probably push it over the magic 80V.

I went for a 1000VA transformer in case I ever added a fifth axis, to be honest though I reckon I could probably add a 9th axis it's so over kill. At 625VA you should be fine with just three steppers, you may or may not need to put together an inrush limiter, you'll probably get away with a Type C or D breaker though - a type D breaker would stay in occasionally for me.

For capacitors I used 4 of these: http://www.ebay.co.uk/itm/1-NEW-NIPPON-100V-10000UF-105-c-Electrolytic-Capacitor-35mmX51mm-B94-LI-/280934713637 Multiple small caps were a lot cheaper than one big one.

I have a bleed resistor which will bleed the capacitors in a few minutes if steppers aren't attached, if steppers are attached they bleed in seconds. I forget what rating it is but it's a lot less than 10.8W, 0.5W rings a bell. I know the recommendation is to bleed the caps in so many seconds but it was a play off between safety and heat produced in the case. To improve safety I fitted a UV style meter to the front of the case to tell me cap voltage and fitted a cover over the capacitors, total cost about £5.

I think you'll want more bootlace ferrules than that and I used a mile of single core cable (can't remember if it was 0.75mm or 1.0). You can get jumper bars for the DIN terminals to make them one large block which came in handy.

[Clive S]

Neil Have I missed the rectifier? The cable for the limit switches can be as small as you like as there is practically no current to speak of.
I have used 25 -25 with no problem and my personal opinion is that the bleed resistor is not needed. ..Clve

[njhussey]

Neil Have I missed the rectifier? The cable for the limit switches can be as small as you like as there is practically no current to speak of.
I have used 25 -25 with no problem and my personal opinion is that the bleed resistor is not needed. ..Clve

Yes you've missed it.....I'm going for a 35A 200V one from Rapidonline....:thumsup:

I'll get some 0.75 tri core shielded cable then for the limit switches.

I think I'll measure the supply voltage here and see what it is out of interest.

[njhussey]

Done some machining today. Also had the rest of my order from Gary @ Zapp this morning.

http://tapatalk.imageshack.com/v2/15/03/04/14d8dd3912dd011a7574163ec6bfd29f.jpg

Machined the Y axis ballnut bracket that connects the Z axis to the Y axis ballscrew...

http://tapatalk.imageshack.com/v2/15/03/04/d274b30e747b337dcb4b00dc19043f7b.jpghttp://tapatalk.imageshack.com/v2/15/03/04/c4b21d04dc328041ed0a608914af820c.jpghttp://tapatalk.imageshack.com/v2/15/03/04/3d3459f50f4813f5406b5e7c7c45fa42.jpg

Seeing as I've got my MGD16 ballnut housings for the X axis I machined the right gantry side.

http://tapatalk.imageshack.com/v2/15/03/04/9bc4175e3d6dffdfb6d41e75c78ad9ea.jpghttp://tapatalk.imageshack.com/v2/15/03/04/6a1b4abf0df485c0338c3db9dcac733a.jpg

More machining tomorrow [emoji2]

[njhussey]

Both ballscrews are fixed to the frame now. Machined the second gantry side for the ballnut holder. I bought some bigger pulleys for the X axis (40 tooth ones instead of 20 tooth ones) as the standard belt I've got is 2525mm and there's a lot of spare belt with the 20 tooth ones. I'm using an 8.7Nm Nema 34 run with a 240V drive so I'm hoping the extra inertia from the pulleys shouldn't cause too much of a problem?

http://tapatalk.imageshack.com/v2/15/03/06/3439eb61ff2d81212982022604a5575e.jpg

http://tapatalk.imageshack.com/v2/15/03/06/cc4b3949f05423d61c79a71b77cd29a6.jpg

http://tapatalk.imageshack.com/v2/15/03/06/c56ce32a4bed21fabeb34c978f37d42e.jpg

http://tapatalk.imageshack.com/v2/15/03/06/9742db0e121ff1a18562c3a373844a5d.jpg

I've bought the transformer, rectifier, 4 4700uf caps and holders, a 600x600x300 cabinet, loads or bootlace ferrules, wire, din rail and terminals, door interlock....tonnes of stuff but I'm sure not everything i need.

I'll be picking people's brains about the safety relay/s for the safety features...

[njhussey]

Did a bit of machining today. Machined 2 x countersunk holes to suit M8 bolts on the Z axis back plate to take the Y axis ballnut bracket.

http://tapatalk.imageshack.com/v2/15/03/09/45498c338cdcd9c0d3e1207075b2bae5.jpg

http://tapatalk.imageshack.com/v2/15/03/09/d282788c51866a65682042c6ed43424a.jpg

The Y axis ballscrew will fix straight onto the back of the gantry so won't need shimming.

http://tapatalk.imageshack.com/v2/15/03/09/28469085ffa69d9b366dca52d787c6ca.jpg

http://tapatalk.imageshack.com/v2/15/03/09/738c728fdf16137866f849237d9e333b.jpg

Scratched my head a bit today trying to work out how to mount the Y axis stepper motor so I can adjust it to tension the belt. In the end I've decided to put the pulley on the rear of the stepper and mount the stepper on the front via a bracket...

http://tapatalk.imageshack.com/v2/15/03/09/31b53f80ceb55e01dc00594e0ce78ea0.jpg

http://tapatalk.imageshack.com/v2/15/03/09/fa6775aaa79e9c2e6fc6b9a74cd0fe07.jpg

I'm hoping that as the only tension on the stepper is from the belt that this arrangement will do?

[toomast]

Nice build sir!

I don't have first hand experience mounting stepper motors this way but it looks trouble. Maybe too much strain on motor?
I guess as long as you fabricated the mount you might as well run it and find out.

Do you have special machining on ballscrew? I notice longer area for the pulley? Or is it just my eyes...

[JAZZCNC]

Scratched my head a bit today trying to work out how to mount the Y axis stepper motor so I can adjust it to tension the belt. In the end I've decided to put the pulley on the rear of the stepper and mount the stepper on the front via a bracket...

I'm hoping that as the only tension on the stepper is from the belt that this arrangement will do?

Bad idea that dude.!! Bearings will suffer and could cause resonance which will affect motor. Just pocket the Mount deeper so pulley goes thru it.
Or have idler arm tensioner tension belt from side of gantry.

[Jonathan]

I agree with JazzCNC - loading the stepper motor bearings so much wont end well...

[njhussey]

I lay awake thinking about that last night and came to the conclusion that I was kidding myself it would be ok and should have known better....I'll pocket it deeper and tension the belt from the side....or weld up a bracket from steel that can slide to tension it. Cheers chaps.

[Clive S]

A bracket could be made to fit in between the top and bottom plates projecting back and lapping around the back face of the two plates ( like a tee piece) it would mean the motor is sticking out the back slightly.
.
"TOOMAST ..Do you have special machining on ballscrew? I notice longer area for the pulley?" Just order the ball screw with the "F" measurement 30mm instead of standard 15mm. ..Clive

[njhussey]

Clive I'm going to pocket out the bracket that I've got and use that with a shorter belt I think....well that's the current plan anyway!

[njhussey]

Quick play on the milling machine...

http://tapatalk.imageshack.com/v2/15/03/10/42544c2e3c32dda3f9f31c8f9c4c89bc.jpg

http://tapatalk.imageshack.com/v2/15/03/10/c60a28fdb91dff53c7aa970d77bdbe6e.jpg

A few bits for my PSU came today....just need some choc block connectors and some fuses and ill be away...

http://tapatalk.imageshack.com/v2/15/03/10/81ea9b169bee966d59d3ccfccfe3d76a.jpg

[njhussey]

Ok so pulled the gantry apart and machined the front and bottom plates (M8 counterbored hole in each)

http://tapatalk.imageshack.com/v2/15/03/10/2aeb6d45c836b5abcc041b288dc51c65.jpg

Put it all back together and it's nice and solid...

http://tapatalk.imageshack.com/v2/15/03/10/5b9f0a94e742bb9c49db49c38ac704df.jpg

Control cabinet and bits arrived just now so more stuff to play with [emoji3]

http://tapatalk.imageshack.com/v2/15/03/10/d485bce5b91688964cf243a566c3155e.jpg

Going over to Wobblycogs tonight to have a catch up, talk CNC Routers and look at his control cabinet to get some inspiration...

[njhussey]

OK quick question. I'm now coming to the end of the mechanical build so my mind's turning to all things electrical :cower:

When connecting the CY cable to the stepper how do you folks do it? I was thinking of either via a chocolate block as near to the stepper as possible or probably I'll go with soldering the wires with heat shrink over them and then heatshrink over the whole lot?

[Jonathan]

I'd expect soldering+heatshrink to be the most reliable way to do it.

[JAZZCNC]

I'd expect soldering+heatshrink to be the most reliable way to do it.

Agreed it's the most hassle free way I find.!

[njhussey]

Cheers, just thought that as long as the joins soldered ok then there's no potential at the join for a loose connection.

Next question! I'm going to get a safety relay (probably a second hand Pilz from ebay) for estops, limits, home switches etc. What's a good model to get, I've seen some Pilz PNOZ X3's which seem to fit the bill?

[routercnc]

I went with a small project box over the area on the stepper motor where the wires exit, making it look a bit tidier. Also adds a bit of impact protection. Inside the box I used a choc-box.

14851

But solder and heatshrink, with the option of netted sleeving also work.

[routercnc]

Cheers, just thought that as long as the joins soldered ok then there's no potential at the join for a loose connection.

Next question! I'm going to get a safety relay (probably a second hand Pilz from ebay) for estops, limits, home switches etc. What's a good model to get, I've seen some Pilz PNOZ X3's which seem to fit the bill?

I'm not going to talk you out of a Pilz style relay as I looked at those as well and was impressed. However, I will mention that a level of safety interlock can be achieved with a cheap multi (4) pole relay - mine was about £8 and has the option of DIN mounting:
14852

One of the poles can be used to form the latch, and the rest are free to switch whatever you need downstream. However, if you don't mind the expense then the Pilz system is neat is and is what the industry seem to use.

[JAZZCNC]

I'm not going to talk you out of a Pilz style relay as I looked at those as well and was impressed. However, I will mention that a level of safety interlock can be achieved with a cheap multi (4) pole relay - mine was about £8 and has the option of DIN mounting:
14852

I agree pilz are nice to have but not really required at DIY level. Normal relays work just as well provided they are correctly sized.

As stated a latching circuit is easily created and standard 24Vdc relays are cheap and easily sourced for any future problems. Depending on level of safety you'll still probably need a plan vanilla relay or 2 anyway as the pilz won't provide enough contacts.!

[routercnc]

I'll also add that all the really cheap Pilz relays I found on ebay were 'spares or repair' so read the advert carefully if you go that route.

[njhussey]

This is now not a plain DIY router but will be at work so I'm going to try and be as safety concious as possible. I'll come up with the number of relays ill need and then see which way to go.

I got the 625VA transformer, will it be beneficial to build a soft start? From reading and talking to Wobblycogs it's right on the edge of needing one. I well oversized it as I left the 6A in the equation by mistake for the Nema 34 motor that's being powered by a 240V drive!!

[njhussey]

I went with a small project box over the area on the stepper motor where the wires exit, making it look a bit tidier. Also adds a bit of impact protection. Inside the box I used a choc-box.

14851

But solder and heatshrink, with the option of netted sleeving also work.
The Z axis stepper will be covered by a cover ill be making from sheet metal to cover the entire Z axis (Jazz's idea) and the Y stepper is enclosed in the gantry (or will be) so the only stepper exposed will be the X axis one, I might look into a cover for that once the machine is up and running. It'll also be tucked away at the top of the router (it's going 80° vertical on its side) at the back so hopefully out of the way.

[routercnc]

[QUOTE=njhussey;67784 This is now not a plain DIY router but will be at work so I'm going to try and be as safety concious as possible. I'll come up with the number of relays ill need and then see which way to go.]

Very good point - I was stuck in the DIY mindset but that's not where you are with this build. This is a machine for use at work, possibly by others, so that puts things in a different light. I know this has been debated numerous times on the forum but yes in this case I'd be following industry standards so carry on !

[Lee Roberts]

I've got a load of new old stock of screened 8, 6 and 4 core alarm cable if anyone needs any, it's worth about £15 a drum on the bay but I can't be asked with that, happy to help anyone out if they would like some.

Should be good for limits and so on?

I've also got a big drum of cable brading as well.

.Me

[njhussey]

I've got a load of new old stock of screened 8, 6 and 4 core alarm cable if anyone needs any, it's worth about £15 a drum on the bay but I can't be asked with that, happy to help anyone out if they would like some.

Should be good for limits and so on?

I've also got a big drum of cable brading as well.

.Me
Thanks for the offer Lee, I've got about 40m each of 0.75mm^2 and 1.5mm^2 CY and a roll of 1mm^2 Tri rated cable of earth red and black so hope I'm going to be ok [emoji2]

[Lee Roberts]

Np's offer is there for everyone, ive got about 10 full rolls and a few ive used so happy to get rid by the meter if anyone wants it.

£5 A Roll + the postage, so prob end up being around half price, 15p a meter if you just want a cut lenth...

Sorry to go off topic just trying to help if I can, build is looking "sweet-as-a-nut!" xx

.Me