DIY mill...

**irving2008** · 30-06-2008

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

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If there's no secondhand Bridgeport available nearby, the best 'of the shelf' deals were from Warren but I am probably out of date.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

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

Originally Posted by Kip

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 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

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

Originally Posted by CheekieMonkies

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...

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

I was thinking about doing somthing with this one:

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

**irving2008** · 03-07-2008

Originally Posted by CheekieMonkies

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

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

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