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irving2008
30-06-2008, 10:15 PM
Can anyone give me pointers to a DIY CNC vertical mill.. I've seen a few but they all seem to be made of MDF or designed to cut MDF... I want something that will do serious metal, well some ally/brass maybe MS anyway...

Maybe I'm wrong but I would have thought a flying gantry design was too weak to be useful on metal so I'm probably looking at a pillar based design?

Robin Hewitt
01-07-2008, 12:28 PM
I reckon the best bet is to choose a mill by sheer weight of iron and available space, then add ball screws stepper motors etc.

If there's no secondhand Bridgeport available nearby, the best 'of the shelf' deals were from Warren but I am probably out of date. I used their Major mill, which seems to have been derated somewhat since I bought mine.

http://www.warco.co.uk/productimages/documents/P61.pdf

irving2008
01-07-2008, 03:08 PM
Thanks Robin,

I wasnt thinking of something that big, I have limited space and funds. I was thinking more along the lines of a DIY pillar drill conversion. I found this http://www.flyelectric.ukgateway.net/mill.htm
by way of example

irving2008
02-07-2008, 10:49 AM
I think the X3 is about the size of a small pillar drill! What size work envelope were you thinking of?Hadn't really thought about it. Depends what I can cobble together and whether to build something as an attachment to the lathe or as a standalone. I found a neat little 2 axis table from Proxxon (http://www.proxxon-direct.com/acatalog/copy_of_micro_compound_table_kt70.html) which is crying out to be CNC'd for only £60 but I'm not sure its robust enough being made of ally not cast iron. What do you think?

Lee Roberts
03-07-2008, 01:46 AM
I hope to build a cnc'd mill soon, think i'm going to use ali and start from scratch. i'v been working on a design in cad but i have now desided to use ali not mdf so its a remodel now. One that will keep the costs down to.

irving2008
03-07-2008, 08:46 AM
I hope to build a cnc'd mill soon, think i'm going to use ali and start from scratch. i'v been working on a design in cad but i have now desided to use ali not mdf so its a remodel now. One that will keep the costs down to.The main issue with a mill for metalworking is rigidity otherwise you wont be able to take any reasonable sort of cut. Which is why I was interested in Kip's ally casting and the potential move to cast iron. His view is ally is too springy for this sort of work, at least for headstocks/quill supports but again it all depends on the design. I'm not convinced a flying gantry design would be rigid enough so I'm considering basing my design around a modified pillar drill...

I just picked this 36" drill with a cast iron foot/head and 9" sq table up of ebay for £15...

http://www.mycncuk.com/forums/photoplog/images/2/medium/1_3611_1.jpg

I know it doesnt look much now, but I think it will serve as a basis once I've done work on the bearings and sorted out a way to preload them. Then maybe shorten the pillar and modify the table

Lee Roberts
03-07-2008, 09:59 PM
I was thinking about doing somthing with this one:

http://www.mycncuk.com/forums/photoplog/images/4/medium/1_DSC04561.JPG

Cost me 40 notes or 50 from Aldi, always find good deals in there !

irving2008
03-07-2008, 10:30 PM
I was thinking about doing somthing with this one:

...

Cost me 40 notes or 50 from Aldi, always find good deals in there !
I have one of those, cost me £20 on sale at B&Q a couple of years back... mine is the Performance Pro version but many places brand the same machine. I think its a bit flimsy for a mill myself, but depends on what you plan to do. The quill may need some serious work as it won't take much radial load on the tiny bearings. They'll need boring out and fitting with something more substantial I think. Mine has acquired lots of axial play after trying to drill 3 x 6mm holes in a chuck backplate :(

Bought my air compressor from Aldi, special offer £100 for the 2.5HP compressor, 30m hose, and about 9 or so air tools - the same stuff (again a branding exercise) is over £200 at MachineMart

irving2008
15-07-2008, 11:57 AM
Things have moved on in the last week or so.. I did my back in picking some paper of the floor by my desk :( so no hard work on the machines and a couple of days off work at home.

Got a bit carried away on fleabay (you know how it is! :) ) and now have enough material for a 300mm X axis and a 200mm Y axis (rails, linear bearings, leadscrew) plus 4 steppers, a 500VA transformer and a 22000uF smoothing capacitor. Stepper driver chip samples are on the way as are power transistors and a few other parts...

Haven't quite worked out what I am going to build exactly but something that will mill PCBs and light aluminium work. All the calcs I have done suggest I could take a .15mm cut with a 10mm endmill in 6061-T6 ali with the stuff I have.

This will need a 50W spindle motor at 3000rpm. I'd want this to be as lightweight as possible and looking at motors that could do the job I was dismayed by their weight (typically 2 - 3kg). Then I was reading up about coolant and how mist cooling is the 'next big thing' and I was musing on how I could use my air compressor to provide the pressurisation using a modified airbrush head when an idea dawned.... why not use the air pressure to drive the milling spindle?

So, has anyone done this and if not, why not?

Robin Hewitt
15-07-2008, 05:10 PM
Because when Edison was criticised because his proposed DC mains supply would require a power station on every city block, he replied that the problem with AC was that it wouldn't run a motor.

Tesla responded by designing and incredible AC motor which is constant speed and brill for running milling machines.

Air is rather the opposite.

But you already know that, you are a one :D

irving2008
15-07-2008, 10:32 PM
Yes, I did some more research... although I havent broken my airdrill out of its packaging the big issue with airpower is lack of torque and constancy of speed... so I'll go back to electric motor....

I noticed on eBay a few drill motors, 14.4 and 18v replacements for cordless.. The specs on these look promising 100W, 55Nm torque at 10mm (I need ~50W, ~15Nm) but the spindle speed will be low, maybe 1800rpm, although I read that 14v motor PWM'd at 25v will run faster... maybe I could belt drive it, 2:1 ratio will give 3600 rpm @ 25Nm...

I also came up with a plan to fix mount the motor and belt drive the spindle on a sprung idler so the spindle could traverse the Y plane but the motor remain stationary. Of course the Z motion will require a splined drive shaft so the upper drive pulley remains fixed.... I'm sure there's a catch somewhere, just don't see it yet....

Robin Hewitt
15-07-2008, 11:49 PM
I was feeling grouchy one day, reckoned my mill was overpowered at 2hp, noisy, had a poor selection of speeds and was not very quick... so I bought a pukka 1hp motor with a matching digital phase converter and computer cable.

Slow to twice normal speed with no loss of power, soft starting, reverse, da woiks.

It's been lying around ever since, but I will do it one day... honest I will :rolleyes:

irving2008
16-07-2008, 12:26 AM
I was feeling grouchy one day, reckoned my mill was overpowered at 2hp, noisy, had a poor selection of speeds and was not very quick... so I bought a pukka 1hp motor with a matching digital phase converter and computer cable.

Slow to twice normal speed with no loss of power, soft starting, reverse, da woiks.

It's been lying around ever since, but I will do it one day... honest I will :rolleyes:and your point Robin? I always finish what I start, well mostly :rolleyes:

Robin Hewitt
16-07-2008, 10:03 AM
My point? :rolleyes:

My point being that I believe the best way to drive a mill is a DPC but I have yet to explore the possibilities.

I have a feeling it would be nice if the machine could autoselect the correct speed from the G code, not start with a bang, maybe apply the brakes so I don't have to wait while it slows down etc :D

irving2008
19-07-2008, 05:10 PM
Well the design progresses slowly...

Been thinking about ways to mount my leadscrews and looking at bearings for the same, namely the 608ZZ that Lee sells...

I have some questions...

1/ Do I really need bearings for 10mm leadscrews max length 400mm. I've not done the calcs yet but gut feel says yes even if its just for the far end....

2/ whats the diameter of the inner rotating part of the race (not the shaft diameter)? My thought is to use a similarly sized OD/8mm ID washer that would act on that to preload the leadscrew with an 8mm ID thrust collar. How do others suggest preloading the screw or do you rely on the motor to control horizontal movement of the screw?

3/ Was thinking about boring out an SK12 or SK13 round rail mount to fit the OD of these races, since that would put the screw centreline at the same height as the rail centre line and is easier than constructing somehting from scratch IMHO. Do you see any issues in doing so? Else what do people suggest as a way to mount the races?

I'll have to machine the ends of the leadscrew down to 8mm (they are 10mm x 2). The leadscrew i have is 400mm long which with machining allowances will work with a 230mm table on 500mm rails giving of 460mm of travel (20mm anti-crash space!).

Not having seen how others do this close up, this is my best guess as to how to approach it. Thoughts?

amen23
19-07-2008, 07:37 PM
I was thinking about doing somthing with this one:

http://www.mycncuk.com/forums/photoplog/images/4/medium/1_DSC04561.JPG

Cost me 40 notes or 50 from Aldi, always find good deals in there !


To me building a cnc machine is like commiting suicide ...it just cant be done in half measures ..you either succeed or you dont. We've all tried to out think the existing technology ... you may be able to build something resembling a cnc with this drill ..but believe me ... after a week you going to be dismantling it to improve it with another idea ... this will continue for the next year .... 2000 notes and 1000 hours later ...you will be buying what you should have bought in the first place!

How do i know this --- been there --- thats is basically how we all started and hind sight can be a b****.

irving2008
24-07-2008, 02:09 PM
eBay got to me again.... picked up a brand new Dewalt D28885 500W 1.7kg die grinder as the basis for my milling spindle for £40, bit cheaper than the £100 asking price for a 500W Kress. There are a couple of places on the Net doing spares for the Dewalt and they list the spindle bearings as type/size 608VV so should be possible to upgrade them later if need be...

Still havent decided if this is going to be a fixed or moving gantry machine... I'm tending towards fixed gantry, moving table in X, moving spindle in Y & Z

Lee Roberts
26-07-2008, 05:40 AM
Well the design progresses slowly...

Been thinking about ways to mount my leadscrews and looking at bearings for the same, namely the 608ZZ that Lee sells...

If its any help to you mate i have got a few of the 608zz's with the zz's missing, there is nothing wrong with the bearings other then the zz missing on one side. I get the odd one or 2 now and again like that so i just use them for testing out ideas as i wouldnt sell them on like that.

I'v also got x4 SK12's sat in my office as well, but i'v just had a look and they wont be big enuff for the 608zz's. i have got lots of SK20's so you could bore them out to 22mm for the 608zz's to fit into?

This is how i went about supporting my leadscrew:
http://www.mycncuk.com/forums/photoplog/images/4/medium/1_DSC04501.JPG

http://www.mycncuk.com/forums/photoplog/images/4/medium/1_DSC04769.JPG

http://www.mycncuk.com/forums/photoplog/images/4/medium/1_DSC02311.JPG

So yea i fitted a bearing at each end of the leadscrews, then i used nuts to preload? the rod a little.

I'v now made this as another solution also in the hope people will find them usefull:

http://www.mycncuk.com/forums/photoplog/images/2/medium/1_DSC05359.JPG



This is a bearing rod support i have designed for other builders and myself, use's a small grubscrew to hold the bearing in place. A key feature of the design I believe to be an advantage over some of the mass produced supports is that it is flush fitting to your machines; this means you donít need to bore big holes to fit it.


If you want some SK20's buy them from my ebay shop and let me know your ebay ID and ill send you the bearings for free. Also wait for me to send you an invoice as i can more then likly do you somthing extra on the invoice as well :).

Cheers,
Lee

Robin Hewitt
26-07-2008, 10:26 AM
What is the lead screw made of? There is a big difference between machining chrome moly steel and machining studding.

Best mount is one axial thrust race at either end and one powerful spring holding it in tension. This is very reassuring when you eventually chuck up your DTI, measure the backlash and have a panic attack. (Not a good idea if working in MDF though, it's about as resilient as marzipan when under load).

irving2008
26-07-2008, 10:53 PM
If its any help to you mate i have got a few of the 608zz's with the zz's missing, there is nothing wrong with the bearings other then the zz missing on one side. I get the odd one or 2 now and again like that so i just use them for testing out ideas as i wouldnt sell them on like that.

I'v also got x4 SK12's sat in my office as well, but i'v just had a look and they wont be big enuff for the 608zz's. i have got lots of SK20's so you could bore them out to 22mm for the 608zz's to fit into?

[...]

I'v now made this as another solution also in the hope people will find them usefull:

If you want some SK20's buy them from my ebay shop and let me know your ebay ID and ill send you the bearings for free. Also wait for me to send you an invoice as i can more then likly do you somthing extra on the invoice as well :).

Cheers,
Lee

Lee, thanks for that, I may need some more 12mm round rail too so I'll be back to you when I've worked out exactly what I am going to do.

I was thinking that SHF20's bored out would also work as per your solution above (is that Delrin?)

I note your leadscrew runs the entire length of the axis. Although it doesnt need to - asuming the connection with the table is in the middle of the table then the leadscrew only needs to be 1/2 the table length plus supporting/machining allowance. This does mean that the end bearing in under the table and not at the end like yours. Apart from the more complex mechanical arrangement is there any other reason not to do this? I'd rather not buy any more 10mm x 2 leadscrew.

Robin - the leadscrew is whatever MarchantDice sell - carbon steel I think.

I'll admit I got a bit carried away and bought their package of 3 lengths - 400mm(X), 350mm(Y), 250mm(Z) - and 3 Delrin nuts before I really thought things through :), and I know know I could have got a better deal from Lee (may still do so), however this is my thinking so far:

I got some 16mm x 500mm rails for the table X traverse. decided to go for a fixed gantry, moving X table as I reckon I can make this more easily rigid than a full moving gantry. With 500mm rails I can get a full traverse on a 230mm table.

The 350mm leadscrew will give me about 200mm usable table width in the Y (assuming the motor mount is ~100mm wide) or I could use the 400mm here to give me 250mm usable table width (in which case I would buy another 600mm of leadscrew at £6 approx). I have some 12mm x 500mm rails which would need to be shortened as appropriate to "Travel + 125mm", i.e. 325mm or 375mm, the remaining rail being used for the Z i.e. 150 or 100mm of travel allowing for mounting.

The remaining leadscrew would give me up to 170mm approx Z travel but I will be limited by the rail length as above.

Here is a quick sketch of the base and X axis. haven't yet decided what to make this of yet... mdf or Ali...

http://www.kisolutionz.com/ttforum/lathe/cncmill.gif

Robin Hewitt
26-07-2008, 11:56 PM
Can you re-arrange and centre support those rails? Would make it lots stronger.

Have you considered reinforced concrete for the base? A bit of granite worktop would be nice. Sand and liquid epoxy if you have the pioneering spirit.

Looks a tadge flimsy as is.

irving2008
27-07-2008, 01:32 AM
Robin, how would you support a round rail with a linear bearing that fully encloses the rail?

these are 16mm carbon steel rails supported at each end - according to my calcs a single rail will deflect no more than 0.04mm under a 35kg central point load and a) I dont plan to load them that much and b) the load is distributed across two pillow blocks on two rails so expect the deflection to be <0.01mm...

Where's the flimsy bit come in?

Irving...

Lee Roberts
27-07-2008, 06:05 AM
lol, OI YOU LEAVE MDF ALONE !!!

Yes it is Delrin.

Yea i used delrin as a drive nut under the table as well mate.

http://www.mycncuk.com/forums/photoplog/images/4/medium/1_DSC04762.JPG

http://www.mycncuk.com/forums/photoplog/images/4/medium/1_DSC04765.JPG

http://www.mycncuk.com/forums/photoplog/images/4/medium/1_DSC04775.JPG

http://www.mycncuk.com/forums/photoplog/images/2/medium/1_DSC05046.JPG



Just let me know when you need anything ill quote you happy !

Lee

Lee Roberts
27-07-2008, 06:08 AM
Forogt to say, i also sell ACME Delrin Drive nuts as well.

They work jsut as well for ACME, i think you may have got ballscrew from Dice.

or was it Anti-Backlash x3pcs 10x2 Trapezoidal + Delrin Nuts CNC (http://cgi.ebay.co.uk/Anti-Backlash-x3pcs-10x2-Trapezoidal-Delrin-Nuts-CNC_W0QQitemZ310069934630QQihZ021QQcategoryZ64819Q QcmdZViewItem)http://pics.ebaystatic.com/aw/pics/uk/s.gif ?

Lee Roberts
27-07-2008, 06:14 AM
Ahh yes there it is: View Item (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280242555450)

Robin Hewitt
27-07-2008, 08:28 AM
Robin, how would you support a round rail with a linear bearing that fully encloses the rail?

Where's the flimsy bit come in?


It's not so much the load, it's sympathetic vibration that may give you headaches.

irving2008
27-07-2008, 11:18 AM
It's not so much the load, it's sympathetic vibration that may give you headaches.Robin,

Its an interesting point. a centre support will reduce the deflection but as we already know thats tiny. But I hadn't considered the resonance aspect. I'll do some calcs to find the resonant freq of the bar and see if theres any issue.

Irving...

irving2008
27-07-2008, 11:23 AM
Ahh yes there it is: View Item (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280242555450)Hey, thats cybersnooping :) in 20/20 hindsight I think I paid over the odds for these, although they sell 3 nuts for £24 alone and the screw is ~£1/100mm so by their prices £21 wasnt so bad.

I'm sure, Lee, you could have done it cheaper and your block 'nut' is easier to mount than the round one (haven't thought how I'm going to mount it yet).

Irving...

irving2008
27-07-2008, 05:38 PM
Robin,

Its an interesting point. a centre support will reduce the deflection but as we already know thats tiny. But I hadn't considered the resonance aspect. I'll do some calcs to find the resonant freq of the bar and see if theres any issue.

Irving...

Well the natural, undamped frequency for a single rail is roughly 287Hz so I'm not sure theres any issue here - all the possible drivers forcing oscillation are at at a considerably lower frequency (min cutter speed 2800rpm - 46rps) so the damping coefficients for forced excitation are large. Also with the two pillow blocks attached there is a significant damping coefficient. There may just be issues with a combination of cutter speed at 17000 rpm (single flute), 8500 rpm (2 flute) or (4250rpm (4 flute) and/or stepping rate of 172mm/min. (Its years since I did any of this stuff at college... makes my brain hurt just reading the equations!)

Of course the proof will be in the actual result...

Robin Hewitt
27-07-2008, 07:49 PM
Maybe I'm just tied up thinking you're going to make deeper cuts in harder materials than you actually are. A speed control can help prevent chatter, but without big heavy slides I'm thinking you really want to get as much spring out of the system as you possibly can :D

irving2008
28-07-2008, 12:15 AM
Robin,

Your points are valid, but I think I'll go without the centre support for now, not least because it severely limits the useful length of the table in the X direction as I will have to make the table longer to allow the maximum travel and the length of the pillow blocks means the overall travel is now reduced, see the pic below and compare to the previous one

http://www.kisolutionz.com/ttforum/lathe/cncmill2.gif

irving2008
28-07-2008, 10:58 PM
This arrived today... 500W, 6mm collet, no measurable runout. 70mm square by 250mm long and a standard 43mm clamp. And it only weighs 1.7Kg... not bad for &#163;40

http://www.kisolutionz.com/ttforum/lathe/dscn1800_1k.jpg

irving2008
08-08-2008, 10:25 AM
Been doing some structural analysis of my proposed gantry frame, planned to be constructed from 50 x 25 x 3mm aluminium rectangular tube.

I found this structural analysis program called 'Framework' downloadable for free from: http://home.wanadoo.nl/wolsink/

It produces load, stress and importantly, displacement analysis for any arbitrary 2D and 3D frameworks.

Here is a screenshot of the calculated displacement for a gantry frame as described with a 10mm thick aluminium spindle support on 16mm round rails - the max displacement under 100N cutting load at the tip of the cutter is 1.01mm in this example (which is clearly too much - and they are exaggerated in the diagram) and most of the displacement is due to bending of the spindle support. I have yet to experiment with making it a U channel instead.

I suspect in reality 100N is far too big a load for a mill doing light cuts on PCBs and Aluminium. Calculations using the torque/HP of the spindle motor and a 4mm 2 flute cutter at 300mm/min feed suggest 20N is more likely giving a 0.2mm displacement which should be easily resolved with a thinner U channel for the spindle support. More work to come tho...

irving2008
08-08-2008, 08:29 PM
That program looks interesting Irving! I wonder if the chip load calculation in Mach3 would correlate with this program? :cheers:The program doesnt do chip load or other machining calculations. It is a general purpose framework analysis. The estimation of forces on the cutting tip which give rise to the twisting moments that cause the frame to distort is not an easy one.

A 500W motor (approx 0.75HP output) at 32000rpm gives .17Nm torque, so the max cutting force before the motor stalls on a 4mm cutter is .17/.002 = 85N, however it probably wouldnt get close to that in reality.

Another way to look at it is the cutting force = chip size x chip removal energy = h * w * E

where E = power * tool efficiency / volume removal rate

Aluminium requires about 0.6W per mm3 so a 300W output motor will only acheive a removal rate of 180mm3/sec

E = 300 * .75/1.8e-7= 16.7e6 and therefore force for a .5mm deep cut on a 4mm endmill is around 16.7e6 *.0005 *.002 = 16.7N

irving2008
09-08-2008, 07:19 PM
Some more calculations using the 'Framework' program.

Option 1 - 50mmx25mmx2mm aluminium rectangular tube for uprights 300mm high (50mm width in X plane), 1 length across the back at the top (50mm width in Z plane). 2 x 16mm horizontal precision rails centrally mounted at top on uprights vertically spaced 100mm (i.e one at 200mm above table and other 300mm above table).

Option 2 - 100mm x 19mm MDF for uprights, 1 length across back (100mm width in Z plane obviously). Rest as above.

in both cases the spindle mount is modelled by a 300mm long x 90mm x 10mm aluminium plate located centrally in Y plane, and at bottom of Z movement. There is 1.7kg dead load (spindle motor) and 20N force in both X and Y planes on the bottom of spindle mount.

The lattice and load diagrams are shown in the attached picture.

The interesting thing is that the X/Y displacement of the spindle tip under 20N load is, for the Aluminium version, 0.22mm/.003mm and for the MDF version is 0.43mm/.004mm which shows that an MDF version is definitely fine for PCB milling (where the load is much smaller) and can probably do lightweight aluminium work but the aluminium frame is prefered for anything more strenuous. These calculations assume all joints are perfect and non-moving. Another interesting thing is that the MDF version weighs 5.4Kg while the Aluminium one is 3.6kg (both including the 2 x 16mm rails and the 'spindle mount'). Aluminium is definitely the way to go, its considerably lighter and more rigid (but not significantly so - doubling the force doubles the offset but thats mainly in the distortion of the spindle mount and rails rather than the frame).

Robin Hewitt
09-08-2008, 09:12 PM
Aluminium requires about 0.6W per mm3 so a 300W output motor will only acheive a removal rate of 180mm3/sec

That's the stuff dreams are made of for me, most I dare cut is around 70 and that involves a degree of tool flexing. I have really irritating software that insists on cutting outlines uphill so I have to leave a generous finishing allowance :D

irving2008
09-08-2008, 10:28 PM
That's the stuff dreams are made of for me, most I dare cut is around 70 and that involves a degree of tool flexing. I have really irritating software that insists on cutting outlines uphill so I have to leave a generous finishing allowance :D

on what equipment Robin?

Robin Hewitt
09-08-2008, 11:04 PM
on what equipment Robin?

One of these, but about 20 years old

http://www.warco.co.uk/productimages/documents/P61.pdf

Robin Hewitt
10-08-2008, 12:16 AM
Hey Robin, What's this weird software?

http://www.gsimple.gr/

It's free and has almost no learning curve if you import a .dxf, I'm using it while I write my own.

irving2008
10-08-2008, 01:19 PM
I'll have a peep at it...Free is a favourite word among Yorkshire folk :DTry CamBam, thats what I've been playing with and works well with EMC2, gnerating the GCode from my CAD package which currently is QCad (also free on Linux if you compile it yourself). Unfortunately CamBam is Windows only and QCad and EMC2 are Linux, so I run QCad in a Linux virtual machine on my Windows PC and then use CamBam to tidy up the DXFs and generate the G-Code then, as both PCs sit on the same network, transfer the file to EMC2 on the Linux CNC-Controller PC where it does lovely simulations at the moment...

I am trying to compile GCam for Linux to get everything working on one system.

irving2008
10-08-2008, 04:04 PM
One of these, but about 20 years old

http://www.warco.co.uk/productimages/documents/P61.pdf
I'm surprised you get that much flex.. do you know how much, and is it the tool flexing or the mill? what feed rate etc?

Robin Hewitt
10-08-2008, 11:48 PM
I'm surprised you get that much flex.. do you know how much, and is it the tool flexing or the mill? what feed rate etc?

Everything bends, the trick is to minimalise it :D

I don't usually post pics of where it goes not so good, but what the heck...

1: Backlash on a change of direction, looks like a ditch, actually 4 or 5 thou deep

2: Chatter, an echo from the roughing out, should have changed speed.

3: Tool flexing, you can see where the tool tip bent inwards and wasn't completely removed by the finishing pass. You know it's the tool becae it gets deeper towards the tip.

irving2008
11-08-2008, 08:23 AM
Everything bends, the trick is to minimalise it :D

I don't usually post pics of where it goes not so good, but what the heck...

1: Backlash on a change of direction, looks like a ditch, actually 4 or 5 thou deep

2: Chatter, an echo from the roughing out, should have changed speed.

3: Tool flexing, you can see where the tool tip bent inwards and wasn't completely removed by the finishing pass. You know it's the tool becae it gets deeper towards the tip.
Thanks for sharing Robin, helps know what I'm looking for... :) btw, #3 are you sure the tool flexed rather than had excessive runout or the work was offline? I'm not sure I understand how the tool tip can bend into the work, unless it was catching because of excessive feed rate

Robin Hewitt
11-08-2008, 01:17 PM
Hard to tell, the way the tool tip digs in much further than the rest makes me suspect tool bending. Could be wrong. I shall find out when my new CNC controller is up and running with absolute positioning from the digital scales.

I was working on the Mk2 version over the weekend, finally burst in to life around 7pm Sunday evening :D

I have a fancy algorythm for CNC milling I want to try. Problem is it needs lots of memory and processor speed, so it has to be a USB device running under XP. I'm taking a crash course in Visual Studio 2008 from a geek :D

Robin Hewitt
12-08-2008, 06:44 PM
Is that a new mount for the end of your table Robin?

I'd have cast it :)

It's not too late for you to cast it, where do I send the pattern? :D

That pic was a freaky bench mounted BB firing test gun. I plugged it in to the shop air line, looked down the shop, saw nothing breakable and pumped a dozen out at around 600 ft/s to test it. One went straight through the wall clock glass front, through the case, luckily missed the mechanism and came out the back :rolleyes:

Lee Roberts
12-08-2008, 07:18 PM
luckily missed the mechanism and

lmao !!!!!

irving2008
20-10-2008, 05:33 PM
Some more bits arrived today :)

A nice project box - actually an IP66 wall mount wiring enclosure but it will house the PSU and driver cards. Being IP66 it is completely sealed but I will put a filtered fan on the side and replace the top wiring gland with a fine mesh (air blowing out the top will keep dust/crap out). It has a nice glas front so I will make up an internal panel with lots of flashy LEDs on it :)

The second is a set of 3 x 4-pole lockdown connectors (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=270288749113)for the steppers, all the way from Hong Kong for under £6 the set, eBay shop is AllPartsPipe. They do 5, 7 and 9 pole too... all rated for 20A DC... and lots of other goodies (Power MOSFETs for instance)

Lee Roberts
20-10-2008, 05:40 PM
its all GOGOGO !!!

I may get to finish some of the things im working this side of xmas !

ciscokiduk
03-03-2009, 09:33 PM
I recently puchased a conquest mill from Chester tools UK with the sole purpose of converting to cnc, I purchased plans for cnc conversion from www.stirlingsteele.com, he has used the Seig x2 for cnc conversion which is basically the conquest in different clothing. I have completed nearly all the X, Y, Z components, now moving on to the controller board etc.

keith77777
29-11-2010, 01:09 AM
Hi you all
Can'nt afford anything like the Seig I'm affraid it has to be good old DIY. I like the plans available on www.crankorgan.com (http://www.crankorgan.com) but not sold to UK. One thing I,ve noticed that if you buy butrussed lead screws they are coarser than studding and you are likely to need bigger stepper motors. The Seig uses Nema23 or 34 wonder what current they take?
Have been investigating software with aim of modifying my motor controller www.calenterprises.co.uk/speed.html (http://www.calenterprises.co.uk/speed.html) for opto coupler. Unfortunately only Mach and maybe Zues are the olny ones to have a PWM output.
If I was making a mill I would use 3 inch angle iron bolted together to stant with then tack welded when everthing had been checked/adjusted. Square tube could be used for slides etc.

Happy Xmas Keith

gavin169
12-06-2011, 09:24 PM
sorry I know but BUMP!

I had to post, just wanted to help some of you were looking for strong lightweight cutting head motors.

Large outrunner motors designed to replace IC. engines in large scale RC aircraft have excellent Power to Weight ratio for examples head to the link provided.

http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?idCategory=222&curPage=10&v=&sortlist=&LiPoConfig=

This is my first post hope to be the first of many is there anyone in northants with one built already that would be able to share some machine time.
Thanks to all, Gavin.

keith77777
02-07-2011, 01:21 AM
Hi Gavin
Yes these motors must have some chuff, I use front loading washing machine motors for machine tools. You can get constant speed from 500---12000RPM. www.calenterprises.co.uk/speed.html (http://www.calenterprises.co.uk/speed.html) I am planning a mill come surface grinder using 60mm pipe for the column, a heavy cast iron block for the table and other bits made from machined cast iron held together with metric screws. Will post some pics when I can be bothered. I only need to flatten stuff out and cut the occasional slot.

Best regards Keith

wiatroda
02-07-2011, 08:59 AM
Hi Gavin
I use front loading washing machine motors for machine tools. You can get constant speed from 500---12000RPM. www.calenterprises.co.uk/speed.html (http://www.calenterprises.co.uk/speed.html)
Best regards Keith
Hi Keith
Do you have experience with those motors??? Any good? I plan to replace my CNC Mill induction motor with washing machine one + controller. Spindle speed variation it is something my CNC machine does need :)
Regards

keith77777
02-07-2011, 07:10 PM
Hi Keith
Do you have experience with those motors??? Any good? I plan to replace my CNC Mill induction motor with washing machine one + controller. Spindle speed variation it is something my CNC machine does need :)
Regards
Hi Gavin
The motors are really good, not enclosed but you can soon make a tinplate caseing. One thing you and I will have to watch when using it for a mill will be the flat belt which normally runs vertically on the washer. I sold a controller to a guy who was fed up of snapping belts on a pillar drill. He put a V belt pulley on the motor shaft. The 12000 RPM is a bit overkill so more pulleys may be necessary but some mills have gearing and use 3000 RPM induction motors. I used the original washing machine pulleys on my lathe.
I am looking forward to strapping this ironwork together and getting a mill/grinder going.

Cheers Keith

keith77777
26-07-2011, 01:05 PM
THUMPING NOT PUMPING IRON !!

Here is a picy of the base of my mill/grinder its a cast iron night storage heater block. Unfortunately its covered with what I find is called cementite. Aptly named, its as hard as diamond and sticks like s--t to a blanket. The only way of getting it off is with a bricky's hammer. If not removed is distroys hacksaw blades and lathe tools. This bit will be used intact but I am using this material for column clamps etc, so there is a fair bit of machining.

keith77777
28-07-2011, 09:04 PM
THE SMART WAY OF THUMPING IRON

Using one of these babies is a lot easier than a hammer especially in confined places. £16 from Aldi it pays to keep an eye on this store. Mind it uses lots of compressed air. The mill grinder I am building is based on
www.neme-s.org/Model_Engineer_Files/swing_grinder.pdf (http://www.neme-s.org/Model_Engineer_Files/swing_grinder.pdf)
Its supposed to be able to grind its own table.

keith77777
29-07-2011, 05:38 PM
Having gotten the base plate cleaned I must turn my attention to taking the flange which is to be welded to the base of the column (6cm pipe) the indispension unit has to be taken to bits. This wheel flange will then bolt the column to the base plate and can be shimmed etc for squareness. Oh I almost forgot the column has to be turned to be uniform in a better lathe than mine before welding. There is a lot to do.

keith77777
02-08-2011, 11:19 AM
It's a concrete lampshade !!

My latest acquirsition from the Cumbria steam rally at the week end. Has a big hole though, will have to give some thought about making an arbor.

Cheers Keith

Robin Hewitt
02-08-2011, 12:17 PM
It's a concrete lampshade !!

There may only be one diamond in the house that will true this thing up, but I suggest you ask her first :naughty:

keith77777
03-08-2011, 10:19 AM
Grindstone cowboy

Hi Robin in the group

I really must broach the subject and duck to avoid flying pans.:lol: I think out of balance would be my gratest worry. Same old Steam rally as 5 years ago always the bloke drilling files. A shortcut to what I am trying to make would be the pillar drill you could make a swinging head by loosening off the head and having it rotate on a collar. Most surface grinders seem to have a trough with the gindstone doing the bis, guess this must be for safety. With having a variable speed motor at least I can keep the revs down for starters.

Cheers Keith

Robin Hewitt
03-08-2011, 11:19 AM
I know nothing about these things, but my gut tells me that if you put this in a pillar drill the taper would let go before you could say, "Bugger".

Plenty of time afterwards though :naughty:

keith77777
03-08-2011, 06:17 PM
I only meant using the pillar stand arrangement, I have a high speed saw spindle with a hole thro one end, a tailour made arbour would be the way. . Yer it is difficult, if you were armour plated or had 1/2 of perspex between you and the work it would be hard to get anything done. I had an abrasive cut-off saw once it scared me so much I gave it away. Angle grinders are very useful but can be as dangerous. I regularly use one for cutting sheet metal, does not crimp the metal like snips. A lot of this stuff is a long way of I have not made the stand yet !!
I am enjoying machining this cast iron in the lathe and making large cuts with old faithful I would send you some if you don;nt mind the postage. :lol:

Cheers Keith

keith77777
30-06-2012, 11:52 AM
Just had the column for my mill turned on a proper lathe mine only traverses the length of the compound slide so no way I could do something this length. The guy did a really good job and also trued the ends up. Next stage is to weld on a wheel flange from those old trailer parts. This will be bolted to the cast iron slab from the night storage heater(with appropiate shims fitted). You know how it is lazyness may set in at any stage. Hows your mill coming on????

Cheers Keith 6211

keith77777
22-10-2013, 03:47 PM
Hello All
I have abandoned the idea of making a vertical mill in favour of a Gingery imitation. I looked at various designs including the Westbury and decided driving a moving vertical spindle was too much of a problem.
The Gingery mill is based on the old Lincoln design using flat belts much easier to accomodate spindle movement.
The bits use angle iron bolted together (tack weld when adjusted). I cheated by buying an X-Y table.
Spindle is from a washing machine drum and I will be useing my motor controller to avoid multiple pulleys. :pride:104901049110492

keith77777
29-10-2013, 08:14 PM
Sorry for my last post having pics all over the place I am an engineer not a computer operator. Any way my mill is progressing. I have to ensure the vertical slide stays at right angles to the bed. 10519

For this I have made a triangle spar here it is colling down in the vice do not want to get burned fingers !!!:adoration:

10520

keith77777
01-11-2013, 01:50 AM
Sorry Lee , Robin and Irvin
You started this thread and the mill that I am making is not CNC at least at the moment. I have no access to machining capabilty except an old lathe which drastically needs new bearings. As I have allready said I considered the Westberry vertical mill design but here were several reports of chattering on the sliding column. Here is a better pic of my design inspired by the Stepperhead, Gingery, Multimachine designes.

10543

10544

Many thanks fer birthday wishes cheers Keith