PDA

View Full Version : Can anyone recommend a spindle for milling PCB and cast acrylic?



HankMcSpank
08-10-2011, 01:04 PM
My requirements are....

1. Low noise (neighbours...and this thing is gonna be on the go a fair bit!)

2. Low runout (but that's pretty much a given with any CNC spindle)

3. Able to handle Acrylic cuts to say 3mm depth without much protesting.

4. Ideally an ER11 collet


A lot use the wolfgang spindle...ok for pcb milling but not much use for anything else (also much talk of the bearings wearing out in short order)

I reckon there's a gap in the market for a spindle that's quiet and can mill pcbs *and* other soft material (anyone entrepreneurail out there?! ...."and for that reason alone - I'm in!")

This guy (stateside) sells something that might suit...

http://www.cnconabudget.com/

but he uses a sewing machine motor - now I've not done a lot of sewing of late so can't gauge how noisy that solution will be!

Any top tips....?

Jonathan
08-10-2011, 01:10 PM
I reckon you should try making a DIY brushless motor spindle:

http://www.mycncuk.com/forums/showthread.php/3096-Using-RC-Brushless-motors-as-spindle

http://www.mycncuk.com/forums/showthread.php/3096-Using-RC-Brushless-motors-as-spindle

For PCBs with a V cutter you can use about 25mm/min per 1000rpm. So with a 24,000rpm spindle about 600mm/min. Probably a bit more but here acceleration will make a big difference. Better off with tiny milling cutters anyway....

HankMcSpank
08-10-2011, 01:17 PM
Hi Jonathan,

My other requirement (should have said) ....buy one that's ready made! (I've little enough free time as it is - without working out how to make one!!)

Anyone want to make one to sell me that will meet my requirements? (btw I realise that traditionally pcb milling is done at very high rpm...but I can forsake that part in exchange for lower noise - I'm getting decent pcm milling results at just 8,000rpm)

Oh yeah, one other requirement - it shouldn't be excessively heavy, it'll likely be going on this very modest CNC machine... http://www.ebay.co.uk/itm/Panther-210-CNC-Router-Engraver-mill-milling-Machine-/230670654180?pt=LH_DefaultDomain_3&hash=item35b50adae4 (the AC spindle he sells makes a right old DIN - have a listen to the youtube video in that advert - on my word, I'd have an ASBO slapped on me after the first pcb!!)

John S
08-10-2011, 01:19 PM
Hank,
I used to run a Kress 800 with the speed knob set to 1 or 2 and it wasn't bad, not ER11's but collets are available. Above 1 or 2 it does get noisy.
Then got one of the air cooled spindles from ARC and run this at 200 hz which is 12,000 for most things, quite quiet, at full speed it's about the same as the Kress on 2.

I believe the water cooled ones are quieter as they don't need a fan but depending on who you buy from in China there is some right rubbish. When we were looking at the air cooled units we wrecked a few until we found a supplier who had inside the unit what they said they had.

The unit from the Stateside looks interesting but only for light work.

For light work the spindles that people are making out of the RC outrunner motors look very interesting, someone was doing a project log on them last month, forget who.

[EDIT] Jonathan got the links into to the brushless motors whilst i was typing.

Jonathan
08-10-2011, 03:30 PM
Anyone want to make one to sell me that will meet my requirements? (btw I realise that traditionally pcb milling is done at very high rpm...but I can forsake that part in exchange for lower noise - I'm getting decent pcm milling results at just 8,000rpm)

Yes I'd be more than happy to make you one...I need to make a freind one soon too. The only thing that might be an issue is how soon do you need it?

I will have a look later for a suitable motor. You can get ER11 collet chucks from 8mm and up, so will probably have to use 8mm to get the required rpm unless I rewind the motor.

John S
08-10-2011, 03:35 PM
Jonathan,
How quiet are these ? If quiet I'd be interested in one to make the build worth while.

Jonathan
08-10-2011, 04:24 PM
Jonathan,
How quiet are these ? If quiet I'd be interested in one to make the build worth while.

Depends how far away you stand :naughty:

I'm not sure really as the only one I have done is the large 6000rpm motor I linked to which is very quiet but then you'd expect that at such a low rpm.
I've got several brushless motors (inrunners) for my model car which do upwards of 60,000rpm and they're fairly noisy but not too bad as there's no fan... so I guess something in between would be fine.
Hmm, that was a very vague answer.

m_c
08-10-2011, 08:10 PM
Hmm, that was a very vague answer.

You've obviously got management potential!
Only management can come out with an answer that doesn't answer the question :naughty:

Jonathan
08-10-2011, 08:30 PM
You've obviously got management potential!
Only management can come out with an answer that doesn't answer the question :naughty:

And politicians!

m_c
08-10-2011, 08:42 PM
And politicians!

Nah. They'd add some bullsh*t in at the same time.

HankMcSpank
11-10-2011, 09:54 PM
Someone's nice related blog here (variation on the rc motor based spindle theme - water cooled too!) ...

http://www.buildlog.net/blog/2011/09/new-brushless-dc-router-spindle/ (he;s linked to all the places he sourced the parts from)


...looks ideal, only weighs 700g & goes upto 30,000rpm!

Want.

(a thread where folks are critiquing his efforts - http://buildlog.net/forum/viewtopic.php?f=25&t=775&sid=ba1d0087f9d40c8a4f75172a0b4b516d)