On Friday 27 December 2013 23:18:04 Steve Stallings did opine:

> We use a similar one, same power unit but an
> older Electrocraft motor instead of the Chinese
> copy. The speed is more or less adequate for
> engraving, around 8000 to 10000 RPM. For the
> one on eBay, I worry about runout. It looks
> like they just used a setscrew to secure the
> collet holder to the motor shaft.

The claim is for .01 to .03 (I assume mm) run out.

> I would guess the minimum speed is related to
> the loss of torque. This control does not
> provide IR compensation for motor loading.

Humm, for serious carving, soft speed control IOW, easily stalled.  Not 
good.

The existing controller for the 200 watt motor on it now is Seriously 
stiff, without any feedback other than the motors emf.  From .150 amps to 
1.5 amps worth of loading is not detectable change in pitch by my ears 
other than an increased level of vibration because its such a toy as I 
increase the feed rate and take bigger chips out.  Etching pcb's OTOH is 
not serious work, but at 12k revs I could run at 10+ ipm, where at 2500, I 
am held to about 1.5 to 2 ipm unless I want to throw up a fin of copper 
instead of cutting.

As for run out, I doubt my MT2 collets are any better, and probably worse.  
I should measure them as I now have a dial indicator whose  marks are 
.0001".

Taking the PWM directly would seem to be an advantage though.

Do you have any more of those 8x2.5mm ball screws?

> Steve Stallings
> 
> > -----Original Message-----
> > From: Gene Heskett [mailto:[email protected]]
> > Sent: Friday, December 27, 2013 5:55 PM
> > To: Enhanced Machine Controller (EMC)
> > Subject: [Emc-users] What do you folks think of this kit for
> > etching pcb's
> > 
> > 
> > <http://www.ebay.com/itm/400W-CNC-Spindle-Motor-Kits-PWM-Speed
> > -Controller-With-Mount-
> > Bracket/221268429297?rt=nc&_trksid=p2047675.m1851&_trkparms=ai
> > d%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D19463%26meid%3D37
> > 02793811656558252%26pid%3D100005%26prg%3D8798%26rk%3D1%26rkt%3
> > D5%26sd%3D380705868216%26>
> > 
> > I am thinking of making up a whole new column and Z drive
> > assembly that
> > I could swap out by 4 bolts & a couple of cables when I wanted to do
> > some pcb work.
> > 
> > LMS has the column, I already have the z sled casting, and I
> > can easily make
> > a fresh ball screw Z drive.
> > 
> > I like the idea that this controller takes a straight pwm
> > signal as input,
> > nut I'm not sure why the 3k revs minimum speed.  Cooling
> > related under load
> > perhaps?
> > 
> > Cheers, Gene
> 
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Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

Man is the only animal that can remain on friendly terms with the
victims he intends to eat until he eats them.
                -- Samuel Butler (1835-1902)
A pen in the hand of this president is far more
dangerous than 200 million guns in the hands of
         law-abiding citizens.

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