Opinions sought on cheap desktop PCB milling machine

[saxonhawthorn]

Hank,

I haven't actually ordered anything yet. A Chinese gentleman is still making overtures for my custom (and offering to teach me Chinese), and I normally like to let purchase decisions rest a while anyway in case I change my mind. But at least having made a choice gives me a starting point for comparisons instead of wandering around in a mental fog.

I do remember seeing those Sable / Panther machines from a couple of years ago, and thinking they looked nice and workmanlike. My instincts agree with yours about moving the table rather than the gantry, but I expect it's a case of horses for courses. I'm not thinking of sculpting a new set of lions for Traffalgar Square, just flat PCBs.

But I haven't thought either about the pros and cons of moving the table in just one horizontal axis, as yours does. There's probably something to be said for keeping only one dimension variable. I need to do some back-of-envelope calcs on tolerances.

And I'm casting glances as I write at my trusty 125W rotary tool, which claims to do 20,000 rpm (a cheapo imitation of a Dremel). I've never measured it, nor have I any idea what its runout may be? But the shaft power should be adequate for milling off a thin sliver of copper. Has anybody tried using something like this for milling?

Ian

[HankMcSpank]

Hank,

I haven't actually ordered anything yet.

It was probably this bit that threw me yesterday...

I have settled on:- a KT150 table, BFB 2000 Mill/Drill Stand, and BFW 40/E Mill/Drill Motor and Controller, all at http://www.proxxon-direct.com/index.html .

If you've not bought a spindle, you could do worse than buying AudioAndy's (if it's still available)....

http://www.mycncuk.com/forums/showth...4773#post24773 ....£80 + delivery is a decent price for a decent low noise spindle (heavy at 4.2kg though!)

Any dremel knock off (dremel's are bad...knockoffs are wose, save for proxxon), is gonna suck wolf's cookies for milling pcbs.

[Jonathan]

Have you considered making your own spindle?

http://www.mycncuk.com/forums/showth...ors-as-spindle

[saxonhawthorn]

Have you considered making your own spindle?

http://www.mycncuk.com/forums/showth...ors-as-spindle

Yes. In fact, that's where I started. I bought Harprit Sandhu's good little book on Spindles (No. 27 in the Workshop Practice series) and it got me motivated-up. Then family matters intervened (two girls at Uni to support) and things got put on hold.

I could still be tempted. ATM I'm mostly hampered by lack of working space (electronic gear, woodworking, metalworking, and book printing & binding stuff all pushing for space). Too many irons in a small fire.

Ian

("I used to be indecisive, but now I'm not so sure!")

[saxonhawthorn]

Any dremel knock off (dremel's are bad...knockoffs are wose, save for proxxon), is gonna suck wolf's cookies for milling pcbs.

Sorry, I didn't express myself well. I was thinking more in terms of using the motor guts with some better bearings, etc, to make a spindle of my own.

And yet another worthless idea from a CNC ignoramus:- Has anybody experimented with dental turbines for PCB milling? They're light and fast and cheap from HK suppliers on eBay, and high-class dental labs work to tenth-of-a-thou standards (or so they tell me).

Ian

[Jonathan]

cheap from HK suppliers on eBay, and high-class dental labs work to tenth-of-a-thou standards

But do the high-class labs buy them from cheap HK suppliers?

[saxonhawthorn]

But do the high-class labs buy them from cheap HK suppliers?

I've no idea, but I could ask tomorrow. A turbine would get the heavy power source off the mill, which in itself sounds an attractive proposition. Sort of thing I'd like to experiment with. But I don't know if it's been tried.

Ian

[Swarfing]

http://www.dieselrc.com/projects/cncspindle/

[ecat]

The Sable machine looks sweet, all aluminium and quite solid. HankMcSpank, did you get stung for duty and shipping?

It looks like you can buy them direct from Holland http://www.cnc-sable.nl/sable-2015-p-21.html , 655 euro including tax for just the base machine + steppers, about £550.00, I don't know if this includes delivery.
N.B. It's best to view the site in Dutch, their English translations are missing some bits.

The home made spindles look beautiful but impossible for those without a lathe. Two complete units I've been looking at are http://www.cnconabudget.com/ - the site looks dodgy but I believe the guy is trustworthy and still in business (info from cnczone), and http://www.wolfgangengineering.com/Home.php . Both of these have fixed 1/8" collets so not quite ideal for me.

[Jonathan]

I wouldn't call a machine that uses unsupported rails 'quite solid', more like quite flimsy espectially since the spacing of the Z-bearings is tiny. Also it appears to only use standard M10 threaded rod for the leadscrews, so you wont reliably get very low backlash which is clearly important for very fine PCBs. Also the steppers are uses are very small, which combined with the low efficiency (compared to ballscrews) of using M10 rod will ensure you can only get low feedrates...

They should not anodise it and use the money saved to improve the machine.

' It can be use for ... litle aluminium work.'

False advertising, as is so often the case. Not very fair on the people who make machines which can cut aluminium at proper speeds.

If you buy that I bet you'll end up replacing most of it.

One way to make a spindle without the lathe is to find a brushless outrunner with a 1/8" shaft and simply replace the shaft with a V-cutter of the same diameter. Not tried it so can't comment on the rutout, and clearly it's hard to change cutters ... but it would be very cheap and very high speed with sufficient cooling. I'm sure blackburn_mark will comment on that as I believe he did it.