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View Full Version : NEW MEMBER: Im new, am a 3D designer. Need a New cnc machine and need advice and guidance



FlyHighRC
03-06-2014, 04:31 AM
Hello, My name is Mike and im 20 years old. I have been using Solidworks for a few years and have become quite fluent with the software. I am keen to turn some of the parts I design(mainly Rc related) into life by the use of a CNC. I understand the concept and have sent Dxf and Stl files to companies to have parts cut and printed for me but would like my own CNC.

Could any of you folk out there point me in the right direction for a CNC.

Basic requirements

1) Be able to cut woods,plastic,carbon& glass fibers, Aluminium
2) be easy to assemble if required,easy to setup
3) cost less than 1200 for machine including electronics. ( CAM and Mach3 already acquired)

it would be a rel help :)

mekanik
03-06-2014, 12:11 PM
Hi Mike
Welcome to the forum.
If you let us know the size of components you intend to produce, our more knowledgeable members will point you in the right direction, a lot tend to build there own as you can end up with a good machine for a lot less cash than some of the commercial stuff that's available.
Regards
Mike

deisel
03-06-2014, 12:11 PM
hello mike
there is nothing off the shelf that I know of within 1200 quid range other than these Chinese 6040 machines that are all over ebay

FlyHighRC
03-06-2014, 12:22 PM
im thinking something along the lines of 600x600x100mm working area... Could you guys fill me in on what you reckon is best of these which I have found so far.

CNC1 (http://www.ebay.com/itm/CNC-Milling-Router-Engraver-Cutter-Mill-Machine-Kit-24-x24-Limited-Time-Sale/261493058990?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222006%26algo%3DSIC.FITP%26ao%3D1% 26asc%3D23309%26meid%3D7352093127171621177%26pid%3 D100011%26prg%3D9834%26rk%3D1%26rkt%3D10%26sd%3D26 1480571805)- I have seen videos of this machine with good results gutting aluminium

CNC2 (http://stoneycnc.co.uk/html/STEPCRAFT_intro_page.html) - I like the look of this machine but there is not much about it online...looks good but i hear allot of chattering while cutting aluminium

CNC3 (http://www.robocutters.co.uk/proddetail.asp?prod=TheOX%21CNC&cat=45) - I like this one because of its low cost but am feeling quite skeptical of its linear movement mecanism, looks like it could be sloppy after allot of use


Thanks guys, so far this is what i have managed to find with my limited knowledge on these machines.

gavztheouch
03-06-2014, 03:04 PM
Hello FlyHighRC,

What sort of tolerances are you looking to achieve with the aluminium?

What thickness of alu are you wishing to cut?

Is cutting time a factor?

deisel
03-06-2014, 04:01 PM
you be pissed off in no time shelling out for them then cutting aluminium

these are the 6040,s I mentioned 3-axis CNC 6040Z-S65J Router Engraver Milling Drilling Cutting Machine CNC 6040 | eBay (http://www.ebay.co.uk/itm/3-axis-CNC-6040Z-S65J-Router-Engraver-Milling-Drilling-Cutting-Machine-CNC-6040-/221455663443?&_trksid=p2056016.l4276)
at least some of them come with a water cooled spindle but I still wouldn't buy that,with aluminium in mind ,although some get by with em and they have a following,with a 1400 quid budget consider making one

george uk
03-06-2014, 04:06 PM
Hi

i dont think i would bother with any of those, like the others sya, you could build your own for that, a little more money, you could build one 10* better. There are already some good designs on here and some already done in sketchup for the size your looking for. I will try find the ones i was looking at in sketchup, they was compleate, I would imagine all them have rigidity and accuracy problems.... You may get away with cutting a wing profile in foam with them, but i think, ( am also into RC ), you might struggle with smaller componants on them. especialy hard small parts ( alu car frame, helli bits, cam holders ). Do You FPV ?

FlyHighRC
03-06-2014, 06:17 PM
Hi

i dont think i would bother with any of those, like the others sya, you could build your own for that, a little more money, you could build one 10* better. There are already some good designs on here and some already done in sketchup for the size your looking for. I will try find the ones i was looking at in sketchup, they was compleate, I would imagine all them have rigidity and accuracy problems.... You may get away with cutting a wing profile in foam with them, but i think, ( am also into RC ), you might struggle with smaller componants on them. especialy hard small parts ( alu car frame, helli bits, cam holders ). Do You FPV ?


Well CNC 1 has been on youtube and seems to go through aluminium fairly easily..6mm 6061 alloy and seems to do it in very little passes. If i wanted to build my own are there any build videos of a known machine where the parts are easy to findbuy and assemble? Id imagine getting the thing tuned would be a bi*ch.

Yeah I am into FPV. I Design Quadcopters mostly. I do love flying FPV and also do allot of survey work
12512

george uk
03-06-2014, 06:52 PM
I live on the coast, and its so relaxing FPVing the coast, and buzzing boats in the humber. I prefer planes, but love team blacksheep vids with quadcopters... I doubt they get permission.

The more rigid the frame, the easier to get repeatable accuracy, your best bet i think would be read through some of the build logs, you will see what problems people overcome, and will see why them three that you pointed at are a basic,

FlyHighRC
03-06-2014, 07:00 PM
So what would I need? I wouldnt mind designing my own design and sticking up some renders on here for you guys to approve..If I build it I could then upload the files for anyone else to have a crack if the design works :) I suppose if its a homebuild then I could Increase its work area right?

The things I know Ill need

1)Steppers motors
2)Stepper wire
3)Link stuff
4)Controller
5)Stepper Drivers(Any all in one driver boards?)
6)Linear mechanisms? Any recommendations for for round bar or square rails?
7)Some sort of router..again any suggestions?
8)sacrifical bed, i see this this is most often MDF

Have I missed anything?

Where can I buy extrusion? And any dimensions online? Would really help with putting this all into Solidworks :)

Thanks again guys

JAZZCNC
03-06-2014, 07:10 PM
Well CNC 1 has been on youtube and seems to go through aluminium fairly easily..6mm 6061 alloy and seems to do it in very little passes. If i wanted to build my own are there any build videos of a known machine where the parts are easy to findbuy and assemble? Id imagine getting the thing tuned would be a bi*ch.

Yeah I am into FPV. I Design Quadcopters mostly. I do love flying FPV and also do allot of survey work
12512

Smoke and Mirrors.!! . . Yes they show it cutting aluminium but what they don't show or tell you is how much it takes out the machine.!
Cutting aluminium correctly needs a much stronger spec machine than any of these. Most machines will scratch Aluminiun away but to cut it correctly and accurately requires rigidity and NONE of these have enough to cut aluminium to any decent standard and survive. They will even struggle on cutting hardwoods at deep depths and decent feed rates.

My advice as usual is to save up a little and build your own or save up a lot and by something much better. The reality is that there isn't anything available to buy off the shelf much under 2.5K that is worth bothering with. The 6040 and these cheap Kits etc are just hassle and false economy, they under perform, break down wear out very quickly if pushed hard, even when not pushed hard they can be fickle things.!

The other thing you need to be aware of is the feed and speeds, Soft materials require higher feed rates and these cheap machines with poor under spec'd components and electronics often can't reach the correct feed rates to give good finish and tool life. If they do manage to reach them then they are often performing at Max capabilitys which puts them under excess stress, at best this leads to inaccuracy and missed steps but worse than that it shortens there life span very quickly.

FlyHighRC
03-06-2014, 07:21 PM
Following my previous comment is it possible to build a machine? for my budget range and achieve good quality?

george uk
03-06-2014, 07:31 PM
just about, but if you up your budjet by a few 100 to say 1500, then yes , you can build a quality machine.

300-500 for motors, controllers BOBs and electricals excluding spindle and controller ( 200-300+)

about the same for linear components ( bearings,slides, screws )

there are about minimum, excluding the frame, if you look about BUT TAKE ADVISE BEFORE YOU BUY ELECTRONICS. BUILD THE FRAME FIRST.

If you know anyone that can weild, you can build a good frame cheaply enough out of steel, just use ally were required

FlyHighRC
03-06-2014, 07:38 PM
IM loosly thinking about designing my own frame and posting the renders for approval by you guys, Is that a good idea or should i find a proven build? If so...know any? :D

JAZZCNC
03-06-2014, 08:17 PM
Following my previous comment is it possible to build a machine? for my budget range and achieve good quality?

Yes but don't be under any illusions that it's easy. To pull this off you will need to be well equiped and have the correct skills to use the tools.
With 1200-1500 budget you will have NO room for error or mistakes buying the wrong components.
Building with steel will cut the costs down but requires it's done correctly to achive accuracy, to be honest at this budget it's about your only option to achive accuracy/strength and still leave enough funds to buy the important stuff that makes for a good machine. These being Profiled linear rails, ballscrews and very important is decent quality electronics.

George runs thru the price of main components but what he doesn't mention is that there's a considerable amount of money that gets eaten up from things folks don't see or account for when planning.? Nut & bolts, Wire, Switches, connectors, cable chain and the list goes on. These can really eat money up fast if not careful.
One thing that often happens with people working on tight Budget is that they cut corners in the wrong places.? Often it's the electronics they turn on because they see this taking a big part of the budget.! This is the worse thing they can do and it's in this area where spending money on the correct components can pay dividends in how the machine performs. Get it wrong and take the cheap skate route and you WILL REGRET.
Next area to get the chop is Linear rails.? They often buy unsupported round rail because it's cheap, which it is, but it's also bendy and CRAP. Other option is to use supported round rail which is better but still not the best and comes with problems of it's own, Like constantly needing adjustment and poor accuracey.

Another area skimped on is the Z axis and material thickness.? The Z axis is THE single most important area of the machine and cutting corners here is BIG mistake as it holds the cutting tool and if this flexs or bends then doesn't matter how well rest of machine is built you'll get poor results.

Best advise is BUY NOTHING YET look around the forum at other builds to judge whats required and if you think you have the skills etc needed. If so then pick or design the kind of machine you require and start a build thread and ask advise. STILL DONT BUY ANYTHING until you have the green light and understand FULLY what and why your buying these componets. Again ASK advise on where to buy as often we will know where they can be bought cheaper.

With a Small Budget you have no room for error and in the blink of an eye with a few wrong clicks you could easily spend all your budget and still be some way off a fully working machine that will still under perform if you haven't done your home work.!!

Good luck and ASK questions before Buying.!!

deisel
03-06-2014, 08:32 PM
So what would I need?
6)Linear mechanisms? Any recommendations for for round bar or square rails?


Where can I buy extrusion? And any dimensions online? Would really help with putting this all into Solidworks :)

Thanks again guys

regarding screws and rail most of us use chia in the link he does the rail and ball screws,there are others but he was the only one ive come across that will machine the screws to length as well as end machineing to your specs to cater for pulleys should you use them.
6SE Linear Bearing Rails 3 ballscrews Balls Screws 1605 BK12 BF12 3 Couplings | eBay (http://www.ebay.com/itm/6se-linear-bearing-Rails-3-ballscrews-balls-screws-1605-BK12-BF12-3-couplings-/251543355322?pt=BI_Heavy_Equipment_Parts&hash=item3a9126ffba)
profile rail would be nice but even used you might be pushing it on your budget.

extrusion.. just one place i and others have used a bit http://www.kjnltd.co.uk/

FlyHighRC
03-06-2014, 09:32 PM
Is it possible to make a good SOLID machine using extrusion? I have read mixed points of view about this stuff...Some say its really ideal for upgrading a machine in the future and provides a good solid frame while other say that its rigidity could be called into question.

I am able to get easy access to a welding machine and welder(friend) but would rather not go down that route( Cutting steel,jiging, powdercoating etc) If i can make a CNC from extrusion..that would be ideal. Though I wouldnt mind making the gantry out of thick steel screwed into the linear blocks. That wouldnt be a problem.

JAZZCNC
04-06-2014, 01:20 AM
Is it possible to make a good SOLID machine using extrusion? I have read mixed points of view about this stuff...Some say its really ideal for upgrading a machine in the future and provides a good solid frame while other say that its rigidity could be called into question.

Yes it is possible but it needs to be done correctly and using heavy duty profile which is very expensive when you factor in the correct fixtures etc required to make it work. Flimsy 40x40 won't cut it and You certainly won't get much machine for 1500 using profile for the frame.
Steel in comparison is very cheap and stronger but requires more effort and skill on the builders part. If your on a budget then forget profile you just won't do it and have machine that's strong enough.

FlyHighRC
04-06-2014, 01:32 AM
Hey guys, Spent most of the day researching CNC designs. I am now pretty sure I want to design my own. I Feel i am able to build this machine...I have a decent workshop filled with tool and my grandfather has a model engineering workshop with manual mills which could come in pretty handy.

The only issue im having is pairing up the hole sizes in the rails to be able to fit the extrusion. This is becoming pretty frsutrating as I cant seem to find extrusion,rails(supported round and linear) that want to fit eachother easily.

Could you guys point me in the right direction of parts that are almost plug 'n' play please.

I also found this CNC Kit (http://www.ebay.com/itm/ballscrew-RM1605-300-900-1150mm-3set-SBR16-linear-slide-rail-BK-BF12-bearing-CNC-/331213230667?pt=BI_Heavy_Equipment_Parts&hash=item4d1dd8d24b) it seems pretty good to me but im not the expert here haha. If you could help Id really appreciate it :tennis:

FlyHighRC
04-06-2014, 01:34 AM
No extrusion then aye...bummer, look much simpler haha

FlyHighRC
04-06-2014, 01:53 AM
a good material? Stainless Steel Box Section - 40mm x 40mm - The Metals Warehouse (http://www.metalswarehouse.co.uk/stainless-steel-box-section-40mm-x-40mm/)

once i get some info on a good material size and price i can start the design :)

JAZZCNC
04-06-2014, 01:59 AM
No extrusion then aye...bummer, look much simpler haha

Ye it can be simpler but not has much as your probably thinking and it will cost at least 3 times the price of steel. I build a machine that uses HD profile but it's used in a very specific way and using thick aluminium plate machined to match so it's not exactly DIY or cheap and you need CNC machine to help build another.! . . Chicken and Egg.!!

Steel will be much cheaper and far easier for first time DIY build.

FlyHighRC
04-06-2014, 02:05 AM
is the above link good enough for the steel frame?

Im hoping to base the machine loosly off of this guys machine...though due to workshop size and the way this machine works it would be difficult to anything over 600x600mm cutting area...just because of the fact the table slides ather than a moving gantry...which to me looks like the better way to get the job done.

JAZZCNC
04-06-2014, 02:06 AM
a good material? Stainless Steel Box Section - 40mm x 40mm - The Metals Warehouse (http://www.metalswarehouse.co.uk/stainless-steel-box-section-40mm-x-40mm/)

once i get some info on a good material size and price i can start the design :)

No 40mm is too small section and you don't need stainless steel. 60 x 60 x 4mm Mild steel is what you need. If you have a local steel supplier it will be cheaper and if you buy in full lengths which will be aprox 7.5mtrs you'll get if for around 40-50 per length or less. The minimum size would be 50x50x3 and can be bought for around 35 per 7.5mtr length.

If you cut careful you should get away with 1 length.

FlyHighRC
04-06-2014, 02:21 AM
Ok,cool :) Ill get on that then... So essentially once the frame is cut,welded and finished you then locate and bolt the rails onto predefined position on the frame, correct? after doing that you then add the stepper motors to the ballscrews, then add the wiring from the motors to the driver boards? then to the powesupply and computer? Make everything look pretty and add a router... is that the assembly in a big nutshell?

JAZZCNC
04-06-2014, 02:45 AM
Ok,cool :) Ill get on that then... So essentially once the frame is cut,welded and finished you then locate and bolt the rails onto predefined position on the frame, correct? after doing that you then add the stepper motors to the ballscrews, then add the wiring from the motors to the driver boards? then to the powesupply and computer? Make everything look pretty and add a router... is that the assembly in a big nutshell?

Wow slow down rover don't go jumping to far in front already. Your nutshell version is a very very very simplified concept and in reality theres a little more to it than that.
Like I said before go do some home work and look at other build threads and designs to get an idea of whats required. This may seem like wasted time but it's not and will payoff when you are ready to start. If you skip this step you will end up with a lesser machine and big potential for wasted money.

FlyHighRC
04-06-2014, 03:15 AM
I Have been researching builds for little under a month so far...thats why i now registered with the forum so that i can start :) I never fully intended building one, but it would be a fun project and would make quadcopter building a fair bit easier..ecspecially cutting wing ribs haha. The builds i have looked at so far were to get an understanding and somevideos are quite enteraining...My CAD abilities will hopefully help me along and to make sure the design is solid before I make the first purchase and cut. Ill post the design on here aswell to see what you fine people think of it :)

A general question... What sort of accuracy can be achieved by an average well built,accurately assembled machine? Can they top some of the commerical machines?

The thing Im finding hardest in terms of research is the general jargon that goes with CNC, after thinking of the dimensions of the machine I would like 900mm rails and 600mm rails. Able to point me in the right direction?

Thanks again

njhussey
04-06-2014, 10:03 AM
I Have been researching builds for little under a month so far...thats why i now registered with the forum so that i can start :) I never fully intended building one, but it would be a fun project and would make quadcopter building a fair bit easier..ecspecially cutting wing ribs haha. Didn't know quads had wing ribs??!! ;)


The builds i have looked at so far were to get an understanding and somevideos are quite enteraining...My CAD abilities will hopefully help me along and to make sure the design is solid before I make the first purchase and cut. Ill post the design on here aswell to see what you fine people think of it :) That's the best way to do it...


A general question... What sort of accuracy can be achieved by an average well built,accurately assembled machine? Can they top some of the commerical machines? Only if you make them ridgid enough and use the correct equipment....but then would you expect to make your own car in your garage and expect it to be better that a production car?


The thing Im finding hardest in terms of research is the general jargon that goes with CNC, after thinking of the dimensions of the machine I would like 900mm rails and 600mm rails. Able to point me in the right direction?

Thanks again

If you have a look through build threads like http://www.mycncuk.com/forums/gantry-router-build-logs/6565-ready-steady-eddy.html this one or http://www.mycncuk.com/forums/gantry-router-build-logs/6457-sturdy-fast-all-steel-cnc-my-first-build.html, http://www.mycncuk.com/forums/gantry-router-build-logs/2288-1-7*0-74*0-4m-mill-router-building.html, http://www.mycncuk.com/forums/gantry-router-build-logs/6484-sufficiently-strong-machine.html then you'll get the drift of what needs doing and roughly in what order. Look through all the build logs and then with your 3D design expertise put a couple of drawings up of the frame for people to critique and you'll be on the way. Once you've got your basic design then AND ONLY THEN can you think of ordering things like ballscrews and rails etc. Once you've got your frame, ballscrews and rails sorted then you can think about the electrics you will need.

FlyHighRC
04-06-2014, 10:31 AM
Thanks, Wasnt expecing his forum to be so saturated with experts at this level on a UK site, Its very nice to see :)

In terms of my design, A plane is designed around engine and passangers, the same for a car in a nutshell. Well To make the design process easier I want to chosse all the size gear Ill need to get it off the ground. So I have found these rails (http://www.ebay.com/itm/3-ballscrews-3-sets-SBR-rails-3sets-BK-BF12-couplers-/250513882178?pt=BI_Heavy_Equipment_Parts&hash=item3a53ca7c42)...Are they good enough? If so I can take the dimensions and add them to solidworks so that the design is built around these giving me the size. Also motor mount dimension would be handy...Stepper motors to me seem to have the same mounting and bolt patterns and are just longer with power...Is this correct?

If so then again, the design process will be easier :)

Im also considering these rails also (http://www.ebay.com/itm/3-ballscrews-3-sets-SBR-rails-3sets-BK-BF15-couplers/250710635207?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222003%26algo%3DSIC.FIT%26ao%3D1%2 6asc%3D23309%26meid%3D7376423196042434753%26pid%3D 100005%26prg%3D9834%26rk%3D6%26rkt%3D6%26sd%3D2505 13882178&rt=nc) quite allot bigger but Im only 20 and am a student so funds are tight so I dont want to outgrow a machine right away... CNC 3D wings would be nice :D

What are your thoughts on going bigger?

george uk
04-06-2014, 10:57 AM
Hi

few tips for you to think about.


Well To make the design process easier I want to chosse all the size gear Ill need to get it off the ground.

Design and build first. for 2 reasons 1. Getting the correct ones. 2 Saving on postage by ordering everything at once


In terms of my design, A plane is designed around engine and passangers, the same for a car in a nutshell.

CnC machine is the other way round. Biuld the frame as solid as you can... the rails, motors and sized around the frame, that why you should do it first


What are your thoughts on going bigger?

It goes up in complexity and costs, it a lot harder to get a big frame properly square, its easyer to get a medium size one accurate. Keep to a reasonable size.

FlyHighRC
04-06-2014, 11:10 AM
I think I will still have to design around the rails, its the way I have been taught and may sound odd but without a reference it becomes difficult to scale the machine,for me anyways.

Are these chinese CNC parts decent quality or are they to stay away from?

A reasonable size sounds reasonable haha. I think I will just do that...I can expand once i get my head around everything and have sufficient finances in the future :)

FlyHighRC
04-06-2014, 11:25 AM
No 40mm is too small section and you don't need stainless steel. 60 x 60 x 4mm Mild steel is what you need. If you have a local steel supplier it will be cheaper and if you buy in full lengths which will be aprox 7.5mtrs you'll get if for around 40-50 per length or less. The minimum size would be 50x50x3 and can be bought for around 35 per 7.5mtr length.

If you cut careful you should get away with 1 length.


Would you say that 16mm supported bar is sufficient for my build? In terms of strength and abilities to machine aluminium?

njhussey
04-06-2014, 11:32 AM
I think I will still have to design around the rails, its the way I have been taught and may sound odd but without a reference it becomes difficult to scale the machine,for me anyways.

Are these chinese CNC parts decent quality or are they to stay away from?

A reasonable size sounds reasonable haha. I think I will just do that...I can expand once i get my head around everything and have sufficient finances in the future :)

What is the max size you want to machine?

As a designer you'll know that first you need to identify the requirement before you can come up with a design/solution. Set out what you want the machine for, then you'll know what size you need to design. Then you can draw your rails and email Chai at linearmotionbearings2008 (ebay store, though don't go through eBay as you get better prices) to get a quote for the rails and balls crews all in one go, the more you order the cheaper prices he'll give you.

What you're saying is a bit like "I've got a 1000kv 24A out runner. ..I'll design my RC plane round that...which although can be done it's better to say I'll design a 1000mm span plane and then after estimating the Wright of it select the motor, ESC etc...

Sent from my Galaxy S5

FlyHighRC
04-06-2014, 11:42 AM
true, Its just the way I have designed before, And the irony is a good designed plane is always designed around the propellor... Oh, I do have some big motors. 1600W to run on 22V, it is lying around and never came up with a use for it...And I have seen people use brushless motors as spindles... any success?

The machine I would Ideally have by the end of this is as:

roughly 800x600mm though that can give or take a bit...though preferably a little bigger than smaller.
Be able to machine carbon/glass fibers, plastics, woods and be able to do some aluminium work without feeling restricted
Be simple,cheap and easy to use.


They are my basic requirements :)

njhussey
04-06-2014, 11:58 AM
If you want 800 x 600 cutting area then your overall size will be approx 1200 x 900 which is just about desktop. My machine is going to have a cutting area of 1000 x 500 so I can cut whole sheets of balsa for ribs etc. Have a look through my build (so far) and you'll get an idea of the size of it, it's larger than you think in the flesh. My frame us from 50 x 50 x 4 mm steel and weighs 70 just for the bare frame...

Sent from my Galaxy S5

FlyHighRC
04-06-2014, 12:53 PM
Putting a plan together for now :) Just to make sure i meet current and possible future targets...making it as future proof as possible...also simple assembly for maintenance and possible upgrades. With ball screws and rails being the parts that judge the machines length what do you think of these (http://www.ebay.com/itm/3-SBR25-sets-3-ballscrews-RM2505-3BK-BF15-3-couplers-/250627640019?pt=BI_Heavy_Equipment_Parts&hash=item3a5a924ad3)? though these are quite a bit larger,would expect the machine tp be in the region of 1600x1200 which is pretty big but i got the room :)

JAZZCNC
04-06-2014, 01:22 PM
With ball screws and rails being the parts that judge the machines length what do you think of these? though these are quite a bit larger,would expect the machine tp be in the region of 1600x1200 which is pretty big but i got the room :)

Your heading into trouble already and doing the classic mistake new builders make by thinking it can't much more difficult to go larger.? Well your wrong it's whole differant ballgame. First and foremost your Budget is blown to bits.!!
Long and wide machines need larger ballscrews and more of them.! Strength needs to increase to keep ridgidty this adds weight This means larger motors, drives, PSU and more of them.! Longer cable chains more wire runs and the list goes on and the cost goes up fast.
Then you have the build it's self with rail alignment and getting on same plane which over longer wider distance requires careful prep and some knowledge which for a first time builder to take on is a risk and not something to do if your on a budget.

My suggestion is take a step back.! Build to your imidate needs not the future as they will 99% change when you actualy start using the CNC machine. You won't upgrade this machine too much from original you will 99% want to build another machine with all your new found needs.
If you build this machine correctly and use decent quality components and electronics you will most likely recover all your initial outlay and possible more. Cut corners and you'll regret it later and will make selling on harder.

Regards the rails then Stay away from round type rails all together because even the supported ones are not so great. Chai as started selling profiled linear rails and they are cheap enough to warrent not using round rail and they make world of differance to the machine and it's sell abilty. They make the diffrance between just average DIY and Great DIY/Professional. They will will certainly add more than there value to the selling price and make sell abilty far higher.

Wal
04-06-2014, 01:34 PM
Hi FlyHigh,

I've had a quick scan of this thread and haven't seen it mentioned yet - bear in mind that the profile of box-section isn't 100% flat and might cause you a bit of grief mounting the rails...

Here's an exaggerated view of what I mean:

12520

Using the epoxy technique is one way to get around this - quite a few on here have employed that particular method - or getting your metal ground flat (a bit pricier...)

Good luck with the build - keep us posted with updates.

Wal.

FlyHighRC
04-06-2014, 02:22 PM
Do you have a link to these linear rails?

I dont know much about CNC but i know how to incorprate strength into a design. If there is one thing Im good at its designing...dont get me wrong...i have seen builds on this forum which to me seem fine but people who have been there and done that have pointed out aspcts of designs that didnt show up to me...but all their critisims and expertise has been written down on my Pukkapad to bear in mind when designing my machine, which will be posted so others can tell me what needs improvong and whats ok etc etc.

Really appreciate the help :)

FlyHighRC
04-06-2014, 02:24 PM
A very helpful tip! Thanks haha. I thought that they probably wont be perfect and could probably do with some work..the epoxy idea sounds good, any particular epoxy? Its just that i have some good westsystems stuff but its made for fiberglass which has a lower viscosity, so might not be hard enough for the job...

JAZZCNC
04-06-2014, 02:31 PM
Do you have a link to these linear rails?

No I don't but just use the Hi-win rails for the model has the spec is virtually the same, height, width etc. If you PM me an email address then I can email you SW files for them.
If you want exact dimensions to model them let me know and I can measure some I have here.

FlyHighRC
04-06-2014, 02:41 PM
I would like to add that in terms of precision welds, I am most likely going to be taking the parts to a machine shop where they will have all the nessesary jigs and fixtures to avoid distortion if i were to tackle this myself. The ideally make the holes for the rails ever so slightly larger than required to give some wiggle room :)

george uk
04-06-2014, 03:30 PM
I would like to add that in terms of precision welds, I am most likely going to be taking the parts to a machine shop where they will have all the nessesary jigs and fixtures to avoid distortion if i were to tackle this myself.

you dont need to be to exreem about the wields, as long as its sort of level on the top, and measures square ( you will see any twists when cutting the steel into parts, its easy to avoid any visible distortions, just use the best bits for the top ). I did the same as your suggesting though, i got a firm to do the welding, after i had cut and marked the pieces.

Epoxy does most of the rest,

FlyHighRC
04-06-2014, 03:34 PM
you dont need to be to exreem about the wields, as long as its sort of level on the top, and measures square ( you will see any twists when cutting the steel into parts, its easy to avoid any visible distortions, just use the best bits for the top ). I did the same as your suggesting though, i got a firm to do the welding, after i had cut and marked the pieces.

Epoxy does most of the rest,


Sounds good :) hopefully i can make a start on the design soon...Just need to pick the rails i want as i can then design the machine around these. 1000 by 600/700 linear rails...know where I can get me some? :D

Wal
04-06-2014, 04:10 PM
I can't really recommend an epoxy as I haven't used this particular technique, but as I understand it does need certain properties for it to work..

Firstly, to be clear - I'm not talking about the method used on this build:

My First Router, Built in Steel - Page 17 (http://www.cnczone.com/forums/cnc-wood-router-project-log/30751-first-router-built-steel-17.html#post568928)

The method I'm referring to is the one where once the frame is assembled/welded, a couple of channels are built onto the rail bearing surfaces (the channels don't need a bottom as the surface of the frame will serve that purpose) these channels are joined by a bridge (probably more than one, which will - of course - need a bottom). Once the frame is reasonably level and the epoxy is poured in, the bridge(s) ensure that the epoxy on both sides of the frame sets at the same height. Once everything's hard, take away the channels/bridges, scrape away the meniscus and voila - parallel, same height rail mounting surfaces.

12529

A few folk on here have used this method and will be able to elucidate further.

Wal.

njhussey
04-06-2014, 04:16 PM
This is my frame in my works...you can see the epoxy on the top...my problem us that I was a numpty and was rushing and got the mix wrong so its not hard enough.....

http://img.tapatalk.com/d/14/06/04/vy3yqequ.jpg

http://img.tapatalk.com/d/14/06/04/esarubuz.jpg

Sent from my Galaxy S5

FlyHighRC
04-06-2014, 09:12 PM
Cool guys, How deep are those channels? Epoxy can be very expensive...and sueply you'd only need a couple mm max!

Can you guys please point me in the direction of linear guider off 1000mm x 600/700mm please :)

Seems not many people know where to find em

Wal
04-06-2014, 09:24 PM
>Cool guys, How deep are those channels?

They don't need to be as deep as I've illustrated 'em - I think 2mm would be under-doing it a bit - mix too little (or if the frame's level is slightly off) and you're maybe gonna end up with bald-spots... I'd calculate for a 5mm thickness of epoxy and don't forget to make the channel wide enough so that the resulting strip of epoxy supports the full width of the rail.

That's about the extent of my knowledge regarding this technique - someone will be along soon to better advise!

Wal.

FlyHighRC
04-06-2014, 09:46 PM
Hey guys, are these compatible?

HGR20 Rail (http://www.cnc4you.co.uk/index.php?route=product/product&path=99_105&product_id=311)

Hiwin HGH20 Square Carriage (http://www.cnc4you.co.uk/index.php?route=product/product&path=103&product_id=314)

Wont be buying them from here, but nice to know i can if needed for whatever reason

Wal
04-06-2014, 10:52 PM
Hey guys, are these compatible?

Yep, should be fine - they appear in each others related items but before buying anything check compatibility via brochures and then double check with the vendor. It's pretty head spinning when you first start looking at the catalogues etc, but after a while drilling down through the relevant info becomes a lot more straightforward. Probably best to ask questions here about the physical characteristics (pitches of screws etc.) of the hardware you want to acquire and whether it'll suit your needs but don't rely on opinions regarding compatibility - although the guys on here are amongst the most helpful and knowledgeable in the community, it's always best to double check yourself..!

Wal.

njhussey
04-06-2014, 11:06 PM
>Cool guys, How deep are those channels?

They don't need to be as deep as I've illustrated 'em - I think 2mm would be under-doing it a bit - mix too little (or if the frame's level is slightly off) and you're maybe gonna end up with bald-spots... I'd calculate for a 5mm thickness of epoxy and don't forget to make the channel wide enough so that the resulting strip of epoxy supports the full width of the rail.

That's about the extent of my knowledge regarding this technique - someone will be along soon to better advise!

Wal.

If you look through the build logs for mine, EddyCurrents and others you'll see that we calculated how much epoxy we'd need. Eddy and I went for approx 5mm.

The width needs to be about 38 mm to give enough either side for the miniscus not to come into play. Also important is to make the bridge wide enough so the epoxy flows ok.

Sent from my Galaxy S5

FlyHighRC
04-06-2014, 11:10 PM
Ideal, Yeah allot of measurements, just googled it to get the dimesnions f 20mm rail and the carriage to pu into CAD. once i made up the rails etc i can start the design....

Any design aspects i should need to know that people often do? Save me going back and forth as much :)

JAZZCNC
04-06-2014, 11:27 PM
Ideal, Yeah allot of measurements, just googled it to get the dimesnions f 20mm rail and the carriage to pu into CAD. once i made up the rails etc i can start the design....

Any design aspects i should need to know that people often do? Save me going back and forth as much :)

Been busy today but I'll email the SW models in next 10 mins.

FlyHighRC
04-06-2014, 11:36 PM
Thanks man, What do you think of the rails and Carriage I posted on the previous page?

JAZZCNC
04-06-2014, 11:49 PM
Thanks man, What do you think of the rails and Carriage I posted on the previous page?

Yes these are the type of thing you need and Hi-win are good quality linear rails just expensive. I've sent email and put a little about rails in it.

FlyHighRC
05-06-2014, 01:36 AM
Yes these are the type of thing you need and Hi-win are good quality linear rails just expensive. I've sent email and put a little about rails in it.


Hey, thanks, I have seen the email...allot of time saved with using these files! much appreciated..

When you sau adjust to suite do you mean extend the rails or shorten the rails in SW, per manufactured one...no point me making one 846mm right.

Ill get to work on a design now then, Any prefernace on something i have seen dont but to me there is no added benefit... Is it better to put the rails on the side of the machine or on top? The one benefit i see is that if its on top you get much more freedom in terms of fine tuning the machine.

JAZZCNC
05-06-2014, 08:57 AM
Hey, thanks, I have seen the email...allot of time saved with using these files! much appreciated..

When you sau adjust to suite do you mean extend the rails or shorten the rails in SW, per manufactured one...no point me making one 846mm right.

Yes just lengthen or shorten to suit your needs. That particular rail is just one I grabbed from a machine design and each machine design will have it's own length version. The Bearing is standard across all machines so only need one instance which you don't change.

FlyHighRC
05-06-2014, 09:13 AM
Ideal, Spent most of last night getting the basic design on paper then spent a couple hours on SW going through a few differnt configurations with this one being the easiest and simplest to make :)

What do you think? There is a piece connecting the rail section underneath going across the X axis. Oh and the board would be MDF...SW doesnt seem to have that
12530

njhussey
05-06-2014, 10:37 AM
That baseboard will bounce and sound like a drum!! That is unless there are lorts of supports underneath it, but I can't see any bolt holes apart from the ones down the outside? Why have you put the rails below the base, all the swarf will drop onto them! How are you going to mount the ballscrews and stepper motors? You're not doing a simgle ballscrew for the X axis are you? What is the gantry going to look like?

Have you looked at the build threads? Most (I do realise that you don't have to go along the same lines as most other people...however there is normally a reason why most of the builds look pretty much the same!!) look like mine below...

1253112532

FlyHighRC
05-06-2014, 10:47 AM
there is one support under the table though I could easily add another :) The table is above the rails to give more rigidity which ill show from the underneath. The, so bare in mind that its not at all done..still fiddling with the design. I see your point about crap going onto the rails but that would happen in most machines...yours even...rather than have the stuff been blown onto them after running alone your board mine will do the same but the machines rubbish will blow off the board and possibly land on the rails...but either way..Im going to add 3mm poly between the gap of the table and the rail carrages...so efficiently having a box where the machined rubbish(Any jargon here) will stay and be easily cleaned up afterwards :)

Ahh, I was planning on ussing a single ballscrew down the middle? Is that a big no no?

Also, the rails that the gantry run on...is there a good distance to keep them from eachother? Assuming that the closer they are the more slop you could possibly get?

My gantrry is 1 vertical piece with a large 40x40x4, 45deg support

FlyHighRC
05-06-2014, 10:54 AM
I had planned on using one ballstrew for each axis... waht you see would have 100mm legs on each corner and would then have a piece connecting each side of the gantry that can be bolted onto the gantry sides to make assembly that bit easier
12533

JAZZCNC
05-06-2014, 12:46 PM
You are weakening the machine having that base like that and it's completely not needed. You need to keep the gantry sides height to a minimum and your creating 60mm more than needed and every bit helps if your wanting to cut aluminium.
If you want the best strength then having raised sides with rails on top with gantry sat directly on bearings is massively strong and much much more suited to an all round machine. If your wanting to cut aluminium then you WILL need 2 ballscrews on the axis moving gantry. This is not just an opinion it's hard learnt and tested thru building many differant machine designs trying to find the best design for an all round machine without being silly about design.

The machine your building with single screws will be fine for mostly wood use and occasional light duty Aluminium work but have no doubts it won't handle cutting aluminium correctly and give quality finish. At a minimum you'll need 2 ballscrews moving gantry to stand any chance and very beefy gantry.

Edit: Oh and the bed base needs far more supports than just one in middle.

FlyHighRC
05-06-2014, 12:56 PM
So loose the second level of boxsection with the board ontop?

Keep gantry height to a minimum

Design in two ballscrews now rather than later

add more support for bed..

got it :) The general gantry design.. Is that ok? with a vertical piece and a 45 member to give some strength... How far should i keep the bearing carriages apart? from the faces that would touch..

njhussey
05-06-2014, 04:02 PM
So loose the second level of boxsection with the board ontop?

Keep gantry height to a minimum

Design in two ballscrews now rather than later

add more support for bed..

got it :) The general gantry design.. Is that ok? with a vertical piece and a 45 member to give some strength... How far should i keep the bearing carriages apart? from the faces that would touch..

IF you've gone through the build logs then you'll see a pattern in the design of the routers built recently which are 90% (this one isn't...http://www.mycncuk.com/forums/gantry-router-build-logs/6988-routercnc_mk3.html) all raised rails above the bed like the pictures I posted previously. They'll also answer most of the questions you're asking about designing them. You don't have to go re-inventing the wheel! Most people on here want to cut the same things that you do (I do as I want to make parts for balsa and ply planes, carbon fibre heli frames and quad frames, ali parts for my helis and quad etc...) so their routers have been designed as a best compromise to achieve this. Re-read all the build threads to see how designs have changed along the build. Mine's a very good example of just this. I started with a similar design as the one you're doing and has evolved as I've read more build logs and asked questions...

routercnc
05-06-2014, 07:31 PM
The 'routercnc_MK3' is my machine and I'll explain why it looks like that.

It was much easier to build it like that based on a simple evolution of the previous version. It is only intended to cut balsa wood, liteply, and plywood and it works very well. I've been using it recently for cutting some 20mm thick aluminium upgrade parts, but that is not the main use.

If I do cut aluminium on my machine (6mm carbide 2 flute cutter) I can run at 1.0mm depth of cut and about 800mm/min feed. Any deeper and I get chatter.

If you want to cut a fair amount of aluminium the raised X axis designs are far superior and probably the best DIY CNC arrangement without simply converting a bridgeport mill to CNC. If you are starting from scratch there is no reason not to really.

FlyHighRC
05-06-2014, 07:31 PM
IF you've gone through the build logs then you'll see a pattern in the design of the routers built recently which are 90% (this one isn't...http://www.mycncuk.com/forums/gantry-router-build-logs/6988-routercnc_mk3.html) all raised rails above the bed like the pictures I posted previously. They'll also answer most of the questions you're asking about designing them. You don't have to go re-inventing the wheel! Most people on here want to cut the same things that you do (I do as I want to make parts for balsa and ply planes, carbon fibre heli frames and quad frames, ali parts for my helis and quad etc...) so their routers have been designed as a best compromise to achieve this. Re-read all the build threads to see how designs have changed along the build. Mine's a very good example of just this. I started with a similar design as the one you're doing and has evolved as I've read more build logs and asked questions...


Not trying to reinvent any wheel, I have lowered the bed...I am still going to keep the sides now as they are good for more strength and will also save me using 3mm poly as a way to stop rubbish going onto the rails...Im quite happy with this though it may need more support on the underneath... I need to make bracket on either end and either side of the machine to hold the motors and ballscrews...

My one concern is the accuracy in welding...if i take the parts to a welding shop will they know how precise this had to be? Dont want them to weld it up and realise its off by a few mm

12534

JAZZCNC
05-06-2014, 08:11 PM
My one concern is the accuracy in welding...if i take the parts to a welding shop will they know how precise this had to be? Dont want them to weld it up and realise its off by a few mm

Don't waste your money because they won't be able to stop distortion only lessen it and in any case you will still need to either use shims or Epoxy method.
Only thing you want to pay special attention to is Twist. If the base frame is twisted then the rails are not on the same plane, Epoxy method is good for sorting this but if you pay carefull attention when welding up then it's possible to get away with just light shimming of the rails. . . BUT with your design the Epoxy method will be much easier and more accurate than your capabiltys to measure rails are on same plane.!

Squareness of base frame isn't critical either square to 1 or 2mm is fine, obviously less is preferable. The important area is the gantry is square to the rails.
The base the cutting bed sits on needs to be resonably flat but again it's not critical as you'll surface the bed before using and this will bring it flat parallel plane.

Like Neil says you really need to go reading some of the build threads more closely and pick up the tips and you'll see whats needed and where your design Lacks or CAN be improved.

FlyHighRC
05-06-2014, 08:42 PM
I have spent allot of time on the build logs so far. Im seeing allot of parts that require a mill and to me that dsrives up cost and complexity. Im sure it increases strength but above my computer I have K.I.S.S which is proving handy :D

A couple questions where I cant seem to find the answer..

When the epoxy is applied to the steel and sets, to bolt on the rail im assuming you just drill and tap? otherwise that must be a very fiddly job getting all them nuts down there haha

carriage space seperation, Is there an optimum distance between the bearings? im assuming the further apart the better but that obviously reduces work area so i guess there is a happy medium somewhere, right?

njhussey
05-06-2014, 10:12 PM
I have spent allot of time on the build logs so far. Im seeing allot of parts that require a mill and to me that dsrives up cost and complexity. Im sure it increases strength but above my computer I have K.I.S.S which is proving handy :D

If you made the gantry out of steel or Ali extrusion you wouldn't need a mill.



A couple questions where I cant seem to find the answer..

When the epoxy is applied to the steel and sets, to bolt on the rail im assuming you just drill and tap? otherwise that must be a very fiddly job getting all them nuts down there haha

Depends on the thickness of the steel. If you've read Eddys build log you'll see he glued in 6mm flat and drilled and tapped into that...



carriage space seperation, Is there an optimum distance between the bearings? im assuming the further apart the better but that obviously reduces work area so i guess there is a happy medium somewhere, right?

Pass...i settled on 200mm as a good compromise between losing cutting area and strength...



Sent from my Galaxy S5

FlyHighRC
05-06-2014, 10:38 PM
Thanks, I prefer the epoxy method thatn gluing some flat bar onto the frame... Purely because it sounds simpler :) Thanks on that! I was thinking nuts inside the box section would be very tedious...any special taps Id need for steel? I have a set of taps but arent made for steel...

In terms of what i said about a Mill, I was talking more along the lines of motor mounts, Even saw one guy with a very nice machine who had his whole gantry cut by laser...

njhussey
05-06-2014, 11:13 PM
The flat bar was as well as epoxy...best sort of taps are spiral flute taps...buy a load on ebay from China they're cheap as chips. Most taps are made for steel, even the cheap black spur ones they sell in pound shops. If you've a good printer, a decent centre punch and a hand drill you can make a decent gantry. Sure a mill helps but ultimately care and attention to details and hand tools are enough if that's all you've got and you want to make a CNC router ;)

Sent from my Galaxy S5

FlyHighRC
05-06-2014, 11:35 PM
Anyone got a SW file for the bit of a ballscrew that is bolted to the gantry? 16mm...I googled the dimension to make one myself but each picture seems to show slightly different dimensions...Why arent all thee bits generic across the board -.-

FlyHighRC
05-06-2014, 11:39 PM
Its not that milling would be a problem, My taid (Wlesh for grandfather) has a workshop for model engineering...he builds those little steam engine that pull 20 people... Also I dont mind getting a few parts done on a laser either... my budget can go up a couple hundred which i can use some for parts to be made...allot of company quotes to come haha. If they all turb out to be stupid in price then ill do it myself.

Clive S
06-06-2014, 01:04 AM
When the epoxy is applied to the steel and sets, to bolt on the rail im assuming you just drill and tap? otherwise that must be a very fiddly job getting all them nuts down there haha



I used 5mm box section and drilled and tapped through the epoxy post 6 here:- http://www.mycncuk.com/forums/gantry-router-build-logs/6403-my-first-project-fast-router.html is the epoxy being poured. Eddycurrent has used a similar system but he glued a flat plate with gorilla glue inside the box section to give more of a bite for the threads. ..Clive

routercnc
06-06-2014, 08:09 AM
.. How far should i keep the bearing carriages apart? ..

With a single ballscrew in the centre then racking becomes a problem whereby the gantry can rotate or twist if you are cutting anything towards the edge of the gantry. To minimise this you can space out the bearings further, but there is a compromise on travel.

With twin ballscrews all these problems go away, which is why it is highly recommended. The gantry cannot rack as a ballscrew holds it at each end. Your considerations then come down to placing the bearings so that the centre of gravity of the gantry (which will be somewhere behind the spindle centre line) and the cutting tool centre line both lie within the region between each bearing, as viewed from the side. If you need to deviate from these positions then don't worry as the profile linear bearings will take quite a load.

As I guide I would say between 100-200mm is about right, probably going closer the 200mm end of the range, giving you maximum travel.

FlyHighRC
06-06-2014, 11:48 AM
for a good machine what is recommended, A router or spindle? cant see any bvious advantage or disadvantages to either... Yet to see anyone give a preference on any of the build logs

Jonathan
06-06-2014, 11:59 AM
Also bear in mind that the deflection of the axis, due to the linear bearings, for a given cutting force is inversely proportional to the square of the bearing spacing. A relatively small increase in the spacing you choose can therefore make a big difference, assuming the stiffness of the system isn't dominated by another weaker part. The reason for this is that the force on each bearing decreases with their spacing and the deflection of the tool also decreases for a given bearing deflection if their spacing is increased, so overall you get a quadratic relationship.


for a good machine what is recommended, A router or spindle? cant see any bvious advantage or disadvantages to either... Yet to see anyone give a preference on any of the build logs

Simple answer is get a proper spindle. But please read the build logs more - people have already linked to some good ones in this thread, yet all the questions you've asked so far are already answered in the logs.

Clive S
06-06-2014, 11:59 AM
for a good machine what is recommended, A router or spindle? cant see any bvious advantage or disadvantages to either... Yet to see anyone give a preference on any of the build logsI don't think you will find many routers on here being used. They are very noisy. The popular spindle is the 2.2Kw water cooled they run very quiet and will run at speeds up to 24,000 rpm. ..Clive

FlyHighRC
06-06-2014, 12:42 PM
So I have nearly completed the first draft of my design, Im very comfortable with being able to make this machine with the tools and equipment I have access too. The gantry im happy with and the way in which the gantry is mounted to the rails. Im also happy with the location of the rails, steppers and mounts etc... the ball screw support blocks have yet to be mounted to a plate(next job) then onto the z axis :)

The frame is mostly 60x60x3mm box section with the gantries vertical section and support section being 40x40x5mm, Hopefully you guys approve this design...in which case I start my budget plan to make sure it can be built within my budget. Then progress to the parts list and DXF files for the laser cut stepper mounts and then go from there :)

Added some colour to give it a bit of life...

12535 12536

njhussey
06-06-2014, 01:42 PM
OK Mike, sorry I'm going to be blunt here. Jazz has said to go through the build logs as have myself, Jonathan and the others I still think you need to go back and do some reading as the design you have put here has been done before (or designs nearly identical to this one) and commented on.

Again being blunt:


Do you have a link to these linear rails?

I dont know much about CNC but i know how to incorprate strength into a design. If there is one thing Im good at its designing...dont get me wrong...i have seen builds on this forum which to me seem fine but people who have been there and done that have pointed out aspcts of designs that didnt show up to me...but all their critisims and expertise has been written down on my Pukkapad to bear in mind when designing my machine, which will be posted so others can tell me what needs improvong and whats ok etc etc.

Really appreciate the help :)

The design you posted is anything but strong...people will have pointed out things in other builds which to you don't show up because they have experience of building the machines, normally by making the same mistakes and regretting it. My brief comments on "first draft"


Bed does not have enough support and will vibrate and bounce giving poor finish.
X axis bearing mount to gantry is too thin and flexible.
Mount the steppers with belts to reduce resonance, not essential but preferable.
Gantry has no bracing or support so will bend/bounce/twist giving poor finish.
40x40 box (for the gantry) isn't strong enough as Jazz said before.


The above assumes that you will be cutting some aluminium at some stage.

Sorry my reply might come accross as being unfriendly and harsh but I can see you going down a route as Jazz said that will leave you dissapointed if you're not careful and if you're not careful you'll waste money prodcing a machine that won't cut what you want to cut.

FlyHighRC
06-06-2014, 02:10 PM
Not at all :) If the design isnt up to the job then its not up to the job. Criticism is how all novices get to a good stage...just like RC haha. I have the CAD files for all th parts I need now, with a number of them provided by Jazz...so the rest is just making a new frame which can still utilise these parts :)

The one thing i really dont understand is how something has to be so strong and precise but are hand welded most often by people who have a mig and no jigs...

Is it possible that the design I have done can be beefed up? with no real change to the machine? Just to save going back and forth...I dont mind, I have taken everyones advice onboard...I know it looks like im rushing into everything but I hav been doing allot of studying on the forums with build logs, The questions I ask which seem similar to other peoples questions are because I want to put it in my own words so I understand it better...

The criticism is good though, didnt show as unfriendly at all, no worries there :)

njhussey
06-06-2014, 02:21 PM
Good man...things can be welded by novices (me!!!) but still precise as long as either some form of adjustment (shimming the top rail on the x axis for exampke) or the epoxy method is employed.

Yes you can still use your design if you look into the gantry a bit more. Bracing is your friend as wood needs to be cut quick so on full chat your machine will be dancing about (how you fixing it down by the way?) all over the place...

The best way to get stiffness in your gantry is to keep the sides as short as possible with the best being to mount it directly on the linear carriages...this needs raised rails.....

Sent from my Galaxy S5

FatFreddie
06-06-2014, 02:29 PM
The one thing i really dont understand is how something has to be so strong and precise but are hand welded most often by people who have a mig and no jigs...

The trick is to be creative about how you get the accuracy. Making a reasonably accurate (+/- 1-2mm) bed is possible with a reasonable amount of skill and care. If this is properly designed it can then be made very accurate using epoxy to level the important faces. On to those now accurate faces you bolt bought in accurate components (the linear rails) and so on.

So, you don't have to worry (too much) about accuracy of the welded frame but you do have to consider its stiffness - it would be worth you reading up on some basic engineering - in particular stiffness of beams. This is not just a 3d design problem, it's also an engineering problem and although you don't need to be able to do accurate stiffness calculations for each part of the machine, you do need to appreciate how the material responds to stresses.

FlyHighRC
06-06-2014, 02:38 PM
Thats good then. If i can still use this general design that would be nice. In terms of the gantry, where the two braces are connecting the two sides, is that where I need to brace? I,e Add vertical members between the two?

Are you a Solidworks user Neil?

FlyHighRC
06-06-2014, 02:46 PM
Yes you can still use your design if you look into the gantry a bit more. Bracing is your friend as wood needs to be cut quick so on full chat your machine will be dancing about (how you fixing it down by the way?) all over the place...


Sent from my Galaxy S5[/QUOTE]

I didnt include it on the solidworks model since i didnt feel the needs but there will be 6 tabs around the bottom of the machine with m6 bolts to bolt it to my other workbench, depending on how much vibration there is i might replace m6 vibration isolation...i use m3 equivalents for quadcopters

FlyHighRC
06-06-2014, 02:53 PM
maybe if this all works out well i can make it an early last year uni project :D

njhussey
06-06-2014, 03:38 PM
Thats good then. If i can still use this general design that would be nice. In terms of the gantry, where the two braces are connecting the two sides, is that where I need to brace? I,e Add vertical members between the two?

Are you a Solidworks user Neil?

Got SW but not installed it...I've got Geomagic Design on my PC at work so trying to get used to that at the moment so won't install it as I don't want to confuse myself (easily done!!)

You need to put in vertical and also cross bracing....like you would in a CF quad arm...

JAZZCNC
06-06-2014, 07:34 PM
Neils bluntness was required here because if you are looking at other builds, esp those built from steel then your not paying attention because you'd have seen NONE are built flimsy regards the Gantry and 99% are done using timing belts and pulleys for connecting to motors. Your design at best is medium duty wood use only.!
Reason for Pulleys is Resonance handling, I'm not getting into how's and why's because it's been covered in many threads so go check some out, But will say it's an important thing on steel framed machines so wouldn't skip it.

Gantry needs to be much more beefed up and braced with plenty of thought to rail alignment and Ballscrew Fixing/adjustment/access. Your design severly lacks here, esp on the Twin axis area. Ballscrew alignment and fixing needs to be strong and easy to setup, if the ballscrew end bearing mounts are flimsy then the screw will resonate which can cause whip and affect performance. If bad then it will also have the similar affect has backlash and causing inaccurecys so design these areas strong and adjustable.
Just remember you have two goals Strength and accurecy, and you can't have one without the other. Build in has much adjustment as possible to allow for the DIY factor, this is KEY to successfull DIY build and stress free build.

Don't be afraid of weight it won't be a problem at this size and will actually give positive affect not negative.

One more note.? . . You've drawn the Gantry bearing plate as Angle iron, this won't be strong enough or accurate enough unless Thick material and prep'd. What you have drawn is has much use as tissue paper.!! . . . The Profiled linear bearings are very intolerent of uneven surfaces and will cause binding if fastened to one. Angle iron isn't flat so it would need surfacing and it will need to be thick material to reduce resonance. Just Fastening to the bench won't stop resonance from weak frame material.
Also beaware it's not a good idea to bolt the machine to the bench unless the bench is perfectly flat and true other wise you'll pull the frame into twist and force the rails out of plane. To be honest this machine won't be light so you won't need to fasten down anyway just level bench and put some buffers to stop machine rocking off the bench.

Neale
06-06-2014, 07:51 PM
Jazz - I know you seem to favour single X motor and belt drive to two screws (for this general size machine, anyway). For a steel machine where resonance might be a problem, is it still better to have a single motor, or two motors with their own drivers to give the drivers the best chance of controlling resonance - and still having motor/screw coupling via belts?

JAZZCNC
06-06-2014, 08:14 PM
Jazz - I know you seem to favour single X motor and belt drive to two screws (for this general size machine, anyway). For a steel machine where resonance might be a problem, is it still better to have a single motor, or two motors with their own drivers to give the drivers the best chance of controlling resonance - and still having motor/screw coupling via belts?

Actually Neale the reason I like Single motor connecting two screws has nothing to do with resonance really just I prefer because of keeping screws in sync.
In either case single or Twin motors belts to motors are best on steel machines and to be honest I fit them on machines I build from aluminium profile and Ali plate for same reason plus they allow flexabilty with ratios if required.

One thing I will say thou is that the newer Digital drives are getting so good at handling resonance or allowing it to be tuned out that it's becoming less important but I still prefer to have them for reasons above.

Edit: Just realised I didn't actually answer your question did I.? Not a politician honest. . Lol

Well one motor is best really due to not having to worry about sync and each drive keeping perfectly together or resonace just affecting one motor/drive not the other etc plus less to go wrong etc. . . .BUT. . . here's the crux with one motor.! . . . It means larger motor is needed and often this throws you into Nema 34 country and with that comes other side affect's like Larger PSU required more expensive drives etc. In reality It doesn't often work out any cheaper than 2 motors/drives really but it does give piece of mind the machine won't tie it's self in knots if one motor stalls and it NEVER Racks or one side loses position if motors are tuned in-correctly.!

Again thou modern Digital drives are helping here with Stall detect and fault signals to help E-stop the system if happens so not so big an issue really. I only Use Digital drives know and Motion control cards which really do help with good fast quality pulse signals so because of this I'm using more 2 motor setups for simplicity sake and avoiding long belt runs.!

Neale
06-06-2014, 09:52 PM
Many thanks for the comments. I'm still building the frame for my new machine, and haven't reached the stage where I have to worry about single or double motors. It brings up a bunch of related issues, so I'll stop hijacking this thread and start another one.

One last vaguely relevant-to-the-thread point, though - I started out a couple of years ago with my MDF JGRO machine in order to make an engraved presentation plaque (immediate need) and the thought that I would be able to cut things like wing ribs, fuselage sides, etc. Haven't done any of the latter yet, but found lots of other uses for the machine that push the (admittedly very modest) limits of what I have. Spent the last couple of days profile-cutting 6mm and 9mm ply components for a slot-together architectural model, and watching the wheels go rounds at a mind-blowing max cutting speed of 700mm/min was tedious. The moral of the story is that if you are happy to cut modest amounts of material at slow speeds, you can get away with a real junk machine. But if you want to be able to do a good job at proper speeds, do it properly first time!

FlyHighRC
07-06-2014, 08:22 AM
Well for me right from the outset I wanted a mchine that is future proof for me (Hence why these guys are pushing so hard ;) ) so that way i can cut plastics,woods and do so ali work in the future and have a machine capable for it all. I was first introduced into CNC at school and was quickly dissapointed with the machines they had... werent very good. Then I got to start using a Roland MDX-540 as part of a young engineers thing.. that machine was better and could chew through plastics...struggled with carbon fiber and did aluminium at 400mm/min, not sure if it could go quicker or the company didnt want to push it but it was annoying to watch frankly.

FlyHighRC
07-06-2014, 09:26 AM
Would this be a better frame? Following a design more towards what other people are making...
12541

FlyHighRC
07-06-2014, 10:03 AM
Oh building a machine to now combat resonance..meaning pulleys..those pulleys will need a special mount t fix onto the ballscrew right? This is now sounding more and more expensive... Please try to remember my budget :D

JAZZCNC
07-06-2014, 10:49 AM
Oh building a machine to now combat resonance..meaning pulleys..those pulleys will need a special mount t fix onto the ballscrew right? This is now sounding more and more expensive... Please try to remember my budget :D

Nothing special needed for using pulleys and the only extra expense are the pulleys & belts roughly 15 per axis. Which isn't much more than direct mounting by time you have bought correct couplings.

FlyHighRC
07-06-2014, 10:58 AM
ahh yeah, just looked at this site, not too bad at all 31T10/25-2 | Ondrives (http://www.ondrives.com/p/9519/31t1025-2)

Im revamping my old design, the frame im happy with...i cant see there being much wrong with it after i strengthen it which was the main critique with it. So I have stiffened that up now. Also the gantry is sitffened up which I will show later, mian change is 2 pieces of 6mm plate welded onto the box section and did away with angle Iron(Which I call L Bar) where the Lbar was is now replaced with 6mm steel welded onto the boxsection

Green is 6mm plate, Note, I will need to extend the bottom 6mmplate awayslightly to make room for the bolts close to the vetical 6mm piece

12542

Clive S
07-06-2014, 11:28 AM
As a matter of interest have you thought about how you will fix the ball nut and bracket to drive the Y axis it seems you are running the screw through the uprights in the gantry. Also there are cheaper places to buy belts and pulleys. ..Clive

FlyHighRC
07-06-2014, 11:31 AM
Yeah I realised that haha, Did it at half 7, Ill put it to the mrning haha, those uprights in the gantry will be behind the horizontal box sections

JAZZCNC
07-06-2014, 11:45 AM
ahh yeah, just looked at this site, not too bad at all 31T10/25-2 | Ondrives[/url

Nah too expensive try these people or go to your local bearing supplier as they are often cheaper and will sell without Vat for cash.
[url]http://www.beltingonline.com/timing-pulleys-bars-272/ (http://www.ondrives.com/p/9519/31t1025-2)

Your gantry is looking slightly better but still needs work. Also by the looks of it you haven't given much thought to how the ballscrew end bearings will mount and how the motor will connect.? Has it stands now it can't be done without special machining and using FF/FK bearing blocks.

10mm plate would be better for the bearing plate 6mm is still a bit flimsy.! Can't afford any flex or resonance here.

Robin Hewitt
07-06-2014, 11:53 AM
Most machines will scratch Aluminiun away but to cut it correctly and accurately requires rigidity and NONE of these have enough to cut aluminium to any decent standard and survive.

I must be misreading this, I thought that Jazz and me would see eye to eye about routing aluminium, I did go to Specsavers so it can't be that.

Did I see that the proposed mill only requires 10mm in the Z axis? Was that a typo? People usually allow 6-12 inches on the Z axis just in case they need it in the future thus destroying the machine for what they actually do. I think 2" or 3" in the Z is optimal if you want 10mm.

If you are going to rout aluminium I further suggest you copy the milling machine. On a milling machine the long bed is only supported in the middle because that is where the cutting happens. No point supporting it where the cutting doesn't happen, let it overhang, no problems.

To make your router strong, bolt Hiwin carriage blocks upside down to something solid such as a concrete joist.

Next bolt your gantry to the same joist so the table can slide through underneath it.

Why not make the gantry out of a second concrete joist? You don't have to move it so go wild on the dead weight.

If you don't like this idea, the usual excuse for not going down this route is, "It takes up twice as much space in the X axis and I haven't got room".

If you want to cut aluminium, design in a flood coolant return from the start, anything else is a ghastly fudge.

FlyHighRC
07-06-2014, 12:40 PM
Nah too expensive try these people or go to your local bearing supplier as they are often cheaper and will sell without Vat for cash.
Timing Pulleys (http://www.beltingonline.com/timing-pulleys-bars-272/)

Your gantry is looking slightly better but still needs work. Also by the looks of it you haven't given much thought to how the ballscrew end bearings will mount and how the motor will connect.? Has it stands now it can't be done without special machining and using FF/FK bearing blocks.

10mm plate would be better for the bearing plate 6mm is still a bit flimsy.! Can't afford any flex or resonance here.


Do you have any SW fil;es for the pulleys? what Pulley width? Im assuming 16mm should do it? That belt must be very strongi guess? When the gantry comes to a sudden stop wont its inertia and the belt cause it to pendulum a little?

FlyHighRC
07-06-2014, 12:59 PM
Right, I have beefed up the gantry quite a bit now, Though the problem IM having now is difficult access...

As you can see from the pictures below, having mounted the block the ballscrew doesnt extend far enough so i though i could add a coupler than add some 6mm rod which will go on one end of the coupler and the other end, the pulley. Pretty complex way so unless you guys say thats ok ill scrap that idea... would also need to cut a whole in the vertical box section to be able to tighen the coupler

12543 12544

njhussey
07-06-2014, 01:03 PM
How's your ball nut on the gantry going to connect to the Z axis? The way youve got it its going to be impossible to connect...

Sent from my Galaxy S5

FlyHighRC
07-06-2014, 01:09 PM
Yeha i know haha, did that at like 7 right out of bed thus was a design that cant be done haha. They will be behind the horizontal box sections :)

Is the pulley mounting system ok? Or in need of a severe redesign?

gavztheouch
07-06-2014, 01:28 PM
It might be easier to use one large piece of box section for the gantry. Something like 150mm by 75mm, that way you have one nice flat surface after expoxy leveling to mount all your rails and ballscrews bearings. You also need a way of tensioning the motor and pully belt, slots in the mount would be fine. You might want your slots in the same axis as the center to center of the motor and pulley?

Another thing, you want to keep the pulley on the ballscrew as close to the bearing as possible.

FlyHighRC
07-06-2014, 01:35 PM
Another thing, you want to keep the pulley on the ballscrew as close to the bearing as possible.[/QUOTE]

so now coupler as a way to extend? :/ If so that allot of travel lost in the y axis... as i would need to bring everything closer but keep machine dimensions similar..

i think the best thing to do is a gantry re design perhaps??

gavztheouch
07-06-2014, 01:48 PM
Check out the other builds and find something similer that works

Wal
07-06-2014, 02:15 PM
>as i would need to bring everything closer but keep machine dimensions similar..

Ahh - compromise!

Hey man, reading through the thread I can see you're very keen to get this done, you're having to take a lot on board in a very short space of time and you have the self-belief - all of this is EXCELLENT. You can get something good built for the money you're talking but given that it's your first build, you just can't rush it.

QUICK CHEAP GOOD

You can have two of the above..!

It is possible to over-think things and there does come a time when you have to take the plunge and just start building, but to put things in to perspective - I spent about a year (more, in fact) on my current machine (most of this was going back and forth design wise) and as it stands it weighs over 100KG (without the base) can cut aluminium/brass quite comfortably and accurately (for my needs: 0.05mm) and has a working area of around 200x200x150mm. I'm happy with it, but there are certainly things I'd do differently if I was making it over again.

What I'm saying is this - if you head down rush into it you may as well buy one of those machines in your original post. It needn't take you as long as what my build took me, but don't expect to have this done within a few weeks.

Have a look at how your grandad works - is he any good? I'll bet he works thoughtfully and steadily if he is...

Just my two cents.

Wal.

JAZZCNC
07-06-2014, 02:20 PM
Can I just say you clearly haven't been doing much research despite your claims that you have.? Why because if you had been looking carefully you wouldn't have made so many errors regards mounting things and the COCKUP with ballscrew running thru those supports shows this clearly.!

Your just wasting time at the moment because your not looking at the details and it's the details that matter most. Anybody can fudge together an outline of a CNC machine but building one requires certain Details are 100% correct and your not seeing them because you haven't looked/read closely enough at other builds. Asking questions is good an I encourage it but asking questions that are clearly in other threads that you have been advised to read is just lazy or you haven't done what you said you had.!!

I'll give you this one last bit of info which you should have seen from other builds then I'm not giving anymore I see which should have been obvious in other threads pointed out to you.!!

15mm wide timing belts, HTD series 5mm pitch no less than 18T pulleys because there isn't enough material left on boss for decent Grub screws after boring, plus better tooth engagement. I use 20T all the time when 1:1 ratio and 18/36 when 2:1

Now go back to reading other threads and start paying attention to the details.!!

JAZZCNC
07-06-2014, 02:31 PM
I must be misreading this, I thought that Jazz and me would see eye to eye about routing aluminium, I did go to Specsavers so it can't be that.
No Robin we don't agree at all. I'm referring to the machines suggested lower down but your still banging on about that old chest nut that Routers can't cut aluminium properly.! . .Which is frankly stupid because there are many of us on here that do it quite nicely thank you.!

Agreed on the concrete machine thou, correct Concrete and epoxy can make a very solid machine.!!

FlyHighRC
07-06-2014, 02:36 PM
The cockup with the ballscrew going through the vertical box sections was a stupid mistake because i was tired...this is CAD..i can make a silly error when im half awake...

In terms of asking questions and reading through other build logs, I have done reseach, maybe not to you exacting needs but done what i consider an acceptbale amount. Things like puley dimensions, im nt going to go rolling thourhg everything an read 99% of things that are all disimportant to me when in 30 minutes one of you guys who knows what your talking about and are being helpful can let me know... now of course,someone could perceive that as lazy...but then how would forums like this be created without that form of contact between members.

Just want to be able to build a good machine, So far you have all helped significantly...redesigning the gantry at the moment. Im not being all 'I know better' which there are a few people like that on most forums of any sort... I changed the whole table layout, gantry and am now redesigning the gantry all together... Your advice so far Jazz has been top notch stuff so dont be upset with me for recognising you know what your doing thus having me(a complete novice in this field) come to you and other experienced members questions you may have already answered before.

FlyHighRC
07-06-2014, 02:44 PM
You are very correct, I have always thought about building a CNC though thought that with 1K i could probably just buy one...then apparently not but then you gus reignited that old idea to build one :)

Yeah im trying not to rush but i do know I can build a CNC machine, I have designed,built and flown functional autonomous survey UAVS before...I can build a CNC. ...But i see exactly your point... Design amtters allot here, as does money which is why your all concerned im getting ahead of myself which i often seem to be doing but i know when im going beyond my limit. My grandads work is very nice, but when it comes down to his work away from his machinning then its similar, paper and his steel haha. He is currently building a racing lawnmower which he has raced a few times...crazy fun thing but it depends on that job at hand.

I am getting less done per hour on this than designing a UAV which is simply down to the fact this is all totally new for me hence spending more while geting less done.

Hope i dont seem groggy haha, Just want a solid design so i can get the price list sorted...

JAZZCNC
07-06-2014, 02:58 PM
In terms of asking questions and reading through other build logs, I have done reseach, maybe not to you exacting needs but done what i consider an acceptbale amount. Things like puley dimensions, im nt going to go rolling thourhg everything an read 99% of things that are all disimportant to me when in 30 minutes one of you guys who knows what your talking about and are being helpful can let me know... now of course,someone could perceive that as lazy...but then how would forums like this be created without that form of contact between members.

Exactly the problem with young people of today.!! . . .They want everything handed on a plate and they want it NOW.

Others and I are not telling you to go away and read other threads because we don't want to answer your questions which we've answered hundreds of times before.! It's about gaining insight and knowledge of what's required and why they choose the parts they did and also the Cockup's they made(if there honest) along learning what makes a GOOD CNC machine tick.
I'm long in the tooth at this game and I've seen and dealt with every type of person/builder and by far the ones who make the best machines with least trouble are those that put in the research and gained the knowledge plus listen before putting pen to paper. Your on a Budget and I can 100% guarantee that if you don't put in the time to research properly how things work and fit together you'll blow that budget out the water.

You are being Lazy by the very fact your asking simple questions that should have been clear if you'd read other threads. It's exacting details that you need to look at because while modelling is great tool for design it's only as good as the detail put into it. When the build begins then the bullshit stops and it's here you realise that because you didn't pay attention to details and model them into your design you suddenly find the Gantry won't move like you thought because you just generlised the part in CAD and now it won't clear this or that.!!

I'm not being high handed here or youth bashing I'm trying to pass on valuable hard learnt experience and Like Wal say's I'll bet your grandad never rushed a single part of his steam engine and I'll also 100% guarantee he did extensive research and took very careful measurements before making any part of it.!!

FlyHighRC
07-06-2014, 03:16 PM
Id rather make the plate... ;)

I am taking it all on... As he noticed i do want a machine up and running asap but thats because I need a CNC to help develop a Survey UAv that is designed for my fathers 3D visualisation company. Thats why I want it quick, never mentioned that because its never been relevant until someone calls me up on it!

Maybe, But its helped me quicker... The noly thing I havent learnt much about so far is the elctronics but im going to make the decision that they arent all that different from 3D printer elctronics exacept maybe bigger supplies etc...

My main concern in building this machine is the electronics, I hate them. Do my head in! Im studying Aeronautical & Mechnical Engineering at Uni with a Electronics module...swear to god its magic!

Robin Hewitt
07-06-2014, 06:24 PM
No Robin we don't agree at all.

That's a relief. I was just doing the forms to renew my gun/explosive certificates, can't afford anything that might cast doubt on my sanity.

Clive S
07-06-2014, 06:41 PM
This must be the longest thread on here with nothing achieved :cower: ..Clive

FlyHighRC
07-06-2014, 08:29 PM
I resent that :P I ahve learnt allot from this bunch, also I reply quick when I want to learn quick..seems most post on this forum are responses 2 weeks apart...

JAZZCNC
07-06-2014, 10:58 PM
I resent that :P I ahve learnt allot from this bunch, also I reply quick when I want to learn quick..seems most post on this forum are responses 2 weeks apart...

They will be if you don't start reading and stop asking annoying questions you should have learnt. .:stupid:

FlyHighRC
08-06-2014, 02:04 AM
Wasnt refering to the people on this thread, You ad two others have been superb in terms of replying :P A compliment :P

Neale
08-06-2014, 09:21 AM
Oh dear, I think we might be going through another 12 pages of posts on the electronics. Router electronics are to 3D printer electronics as F1 cars are to go-karts. The principles are the same but...

FlyHighRC
08-06-2014, 07:42 PM
Hello again, Right After going thourgh more of the build logs..Updated teh design of my gantry...people using 10mm 2D cut steel and wled it all together, Im using 6mm and have just reinforced it allot... Simply for cost. When it comes to driving the belts, I have done the drive system using the belts and Pulleys Jazz reccomended(your real name?) I did the basic calculation to get the mtor shaft to pulley distane and added a couple holes where i can add tensionsers if the tensions isnt quite right..

When it comes to the X axis, Its currently using two motors...but reading around Im seeing a fair few people having issues with losing steps (similar to z axis on 3D printers) how much of an issue is this? If so Ill redesign for a big belt using one Nema 34 motor driving both ballscrews (cant find it but saw a diagram you posted Jazz...)

Help? :victorious:

JAZZCNC
08-06-2014, 09:43 PM
When it comes to the X axis, Its currently using two motors...but reading around Im seeing a fair few people having issues with losing steps (similar to z axis on 3D printers) how much of an issue is this? If so Ill redesign for a big belt using one Nema 34 motor driving both ballscrews (cant find it but saw a diagram you posted Jazz...)

Ok well don't worry about losing steps. Those who are losing steps have usually either overtuned the motors or have mechanical issues. If you use decent electronics and don't be greedy regards tuning then you won't have any issues. Regards electronics then get out your head any relationship to 3D printers and absolutley don't look to buy electrics intended for 3D printers they are far removed from each other.

Single motor and belts do give peace of mind about not racking and do allow faster feeds has they can be run closer to the motors limits with worrying about stalling. But like you will have seen me say before if you've read other posts if twin motors are setup correctly and run comfortably within the motors torque capabiltys then you don't have any problems for majority of work. If running very long 3D work(15hrs+) then I prefer twin belts as you know one motor can't run out of sync with other.!

Keep reading and you'll find my Name. .:thumsup:

FlyHighRC
08-06-2014, 10:04 PM
Awesome, Ill stay away from 3D printer electronics then :)

'If running very long 3D work(15hrs+) then I prefer twin belts as you know one motor can't run out of sync with other' By this do you mean the single motor system?

Here is the machine so far, The gantry side are completely different though the Y axis section is similar with some ugly looking supports, Might do what another member said about one 40x80mm piece running the length... Also still need to add laser cut steel peices for mounting the ballscrew supports at either end of the X axis...Pay no attention to the other side of the machine...I mate everything on one side then mirror and remate on the other...saves inserting the same parts over..

12550

FlyHighRC
09-06-2014, 12:43 AM
If this is approved Ill Take this over as a build Log :)

njhussey
09-06-2014, 09:43 AM
How are you getting the steel the rails are sitting on flat? If you're going the epoxy route you might want to give consideration ax to how you're going to get the joining bridge between the rails?

Sent from my Galaxy S5

Robin Hewitt
09-06-2014, 12:46 PM
If you go with 2 motors on one axis, remember there are 2 kinds of stepper drivers. When you power up some will remember the last coil pattern used and some won't.

Clive S
09-06-2014, 12:55 PM
If you go with 2 motors on one axis, remember there are 2 kinds of stepper drivers. When you power up some will remember the last coil pattern used and some won't.
Would you mind expanding on that, as I don't understand. ..Clive

Neale
09-06-2014, 01:10 PM
A stepper motor has two sets of coils, say A and B. If you home the twin-motor setup, it might be that the home positions correspond to A on one and B on the other energised. Switch off, switch on again, and some drivers (I suspect all analogue drivers) will energise A rather then remembering the last coil used, so the gantry will be slightly off-square. I'm assuming that a rehome operation will reset this, but the moral is that you can't rely on the system remembering exactly where it was when it was switched off. Slightly more complicated if you are using micro-stepping but the principle is the same. Small effect if you do it once, but the error could accumulate over a number of on/off cycles unless you rehome at the start of each session.

Clive S
09-06-2014, 03:19 PM
A stepper motor has two sets of coils, say A and B. If you home the twin-motor setup, it might be that the home positions correspond to A on one and B on the other energised. Switch off, switch on again, and some drivers (I suspect all analogue drivers) will energise A rather then remembering the last coil used, so the gantry will be slightly off-square. I'm assuming that a rehome operation will reset this, but the moral is that you can't rely on the system remembering exactly where it was when it was switched off. Slightly more complicated if you are using micro-stepping but the principle is the same. Small effect if you do it once, but the error could accumulate over a number of on/off cycles unless you rehome at the start of each session.

Thanks for that Neal I would assume that most people would home each time they fired the system up and if they did not have home switches they would zero on the part. So generally would not be an issue. ..Clive

JAZZCNC
09-06-2014, 04:10 PM
If you go with 2 motors on one axis, remember there are 2 kinds of stepper drivers. When you power up some will remember the last coil pattern used and some won't.

Doesn't make a Jot of difference if using Home switches which you really should use with Twin motors.
It's good practice to home the machine when first switched on and Most industrial machine won't let the machine function untill the machine as been homed. This ensures your setup and square so any step jumps on startup doesn't come into play.
It's also best to home the machine between every job if not shutting down just to remove any errors that may have crept in over period of the last job. This is why I prefer single motor/belts on machines that will be running single jobs for 12hrs +.

FlyHighRC
09-06-2014, 04:43 PM
Thats the only issue with the design, I noticed exactly what your talking about...Well alteast i think haha, The gantry... when adding all the components to the gantry ill have to do so in a certain order...and if say the whole gantry is assembled and i need to removed the ballscrew but then id have o dismantle the whole thing... the only issue i can see.

I will be having the machine welded up then going ahead with the expxy method..

Robin Hewitt
09-06-2014, 06:46 PM
Doesn't make a Jot of difference

I can tell you have never had to write the manual :toot:

Problem with writing the manual is you have to cover all the bases, because you know some geek is going to figure out the problem and ask you why it isn't a problem. You have to try and out geek the geeks by spotting all the snags before they do. Patting a geek on the head and saying, "Don't worry about it sonny" does not work. They can smell fear.

Let's suppose your driver(s) are the forgetful step pattern kind. They always fire up on the same pattern, a pattern that will repeat every 1.8 degrees.

Now suppose you parked the machine 0.9 degrees out of phase to that so when you power up it can leap either way.

Suppose one leaps CW and the other CCW, both equally valid. The gantry is now out of square. You can bump every home switch in Christendom but the most you can do is detect the error, you can't fix it unless you can drive the motors independently.

JAZZCNC
09-06-2014, 10:52 PM
Suppose one leaps CW and the other CCW, both equally valid. The gantry is now out of square. You can bump every home switch in Christendom but the most you can do is detect the error, you can't fix it unless you can drive the motors independently.

Yes agreed but you obviously have no experience of how twin axis slaving works with home switches. They do move the motors independant so I'll say it again "It doesn't make a Jot of difference if you use home switches" Your argument only works if you don't use home switches and when slaving motors you should always use home switches.
Now to clear the Geek fear manual you have, which is unfair to geeks really, i'd call them fucking idiots my self then I'll clarify by saying "Separate home switches on Slaved axis motors"

Lee Roberts
10-06-2014, 12:52 AM
Can someone clarify what a "twin axis" is please, I've tried to find information on it but everything I found relates to minerals or more specifically crystals.

I even tried "twin axis slaving" but I already new about setting up slaved motors in Mach 3, so those results didn't really help, the correlation please.

.Me

JAZZCNC
10-06-2014, 01:28 AM
Can someone clarify what a "twin axis" is please, I've tried to find information on it but everything I found relates to minerals or more specifically crystals.

I even tried "twin axis slaving" but I already new about setting up slaved motors in Mach 3, so those results didn't really help, the correlation please.

.Me

Lee if you don't know by now then you need to hang up your boots mate. . :loyal:

Suppose Twin Axis is wrong really.? Should be "Single Axis Twin motors slaved together" . . . . . Try that it will probably come up with Match.COM.!!