Looking for advice on budget machine for watchmaking

[lanky_streak]

I'm an industrial designer looking to purchase my first CNC machine and would appreciate any advice on what's best suited to my requirements. The type of work I'll be looking for from this machine is for watch parts, namely dial engraving (aluminium / brass), watch bridge fabrication (brass) and ideally engraving stainless steel casebacks. Ideally it'd be capable of making aluminium watch cases, but that's not an essential requirement. I'm not against a DIY build, but as I know relatively little about CNC machines, I'd be more comfortable with an off-the-shelf solution / CNC machine 'kit'. To create watch bridges, I'll need to be acheiving +/-0.01mm accuracy in the X/Y axis - machining speed is relatively unimportant at the moment. My budget is a rather small £1-2k for the machine alone (I'd really like to keep it under £1500 if possible).

The options I'd considered so far are a converted Taig / Peatol mill with CNC conversion (and 4th axis), I've heard that an EMCO F1 would be more than capable if it can be found, and I'd also considered one of the CNC frame kits combined with C7 ballscrews / air-cooled spindle (Chinese with replacement VFD). I'm leaning towards the converted mill as I don't need a large working area, and these look like fairly 'solid' machines, but I'm also aware of just how little I know on the subject! If anybody with more experience has any suggestions, it'd be greatly appreciated. Thanks!

[GEOFFREY]

Hi, wellcome to the forum. I think that you would be better with a small cnc mill. I think a Denford would be a good choice, although you would probably need to convert it to modern electronics and use mach 3. Good luck with whatever you decide to do. G.

[EddyCurrent]

Way over budget but this has the accuracy you are looking for, so it says.
Buy Axminster SIEG KX3S CNC Mill from Axminster, fast delivery for the UK

More affordable, you could add cnc parts yourself maybe.
SIEG Milling Machines - Arc Euro Trade

Denford Novamill CNC Milling Machine With All Computer Programmes Ready To Use | eBay

[JAZZCNC]

You'll defiantly be wanting a small mill or Purpose built sturdy Fixed gantry machine but with your requirements for engraving and aluminium work with tight tolerances plus relatively low budget when it comes to off the shelf CNC you'll struggle to find anything suitable.!!

You'll certainly find something available at your budget but they won't be ideal for your type of work because the spindle speeds are little on the low side with mini-mills and for a decent finish on aluminium/brass with small cutters you'll need 7-8Krpm speeds minimum and for good engraving you'll want 20Krpm minimum most mills will top out at 3Krpm.
Also chances are the mill spindles will have higher run-out and for fine engraving you'll need better than most cheap mills provide.

My suggestion is build a small sturdy fixed gantry machine out of steel so it's very strong, use profile linear rails on all axis with 5mm pitch ballscrews. Add to that Chinese WC spindle combined with Good quality digital drives and you'll have a very capable purpose built machine easily done within your budget. . . . . Any off the shelf machine equally equipped or capable will be 5K minimum.

[birchy]

I'm afraid that as precision increases, so does the cost. I wouldn't look at anything less than a closed-loop drive system...ideally go for Servo drives rather than stepper motors. The main issue will be the mechanics...I'd suggest building a small machine using precision rails on such a tight budget.

[lanky_streak]

Thanks for the replies, I really appreciate the detailed responses. I'll think I'll have to do a lot more research before deciding on building anything from the ground-up, but given the budget and the fact I'll need to get up to speed on how the machine works anyway, that's no bad thing.

One question on the closed loop system, is that something that can basically be added to any mill or are custom controllers / sensors required?

And for Jazzcnc, I've read a few comparisons (and still don't have an answer!), but is the watercooled spindle significantly better than the air cooled to warrant the additional complexity of a plumbed system?

The last CNC machine I had experience of was a Datron M8, and I see they do have an 'inline' mini-mill which looks great, but presumably as a 'POA' product, this isn't one for a hobbyist?!