--- In
Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@...> wrote:
>
> Of course you could use a DC or AC universal motor. Both will run just
> fine with PWM.
> AC universal motors will also run just fine with phase angle control
> (like a light dimmer). That's what's in variable speed power drills.
>
> But they have brushes, so get some earplugs ;-)
>
> I have no idea how well any type of gearing will hold up at that
> speed. That's why i suggested direct drive.
>
> You can make your own brushless motors if you like, or buy one and
> operate it mucht below it's design power output (like 10 times), then
> it should not overheat.
>
> PCB drilling, especially small drills, requires virtually no torque.
> Friction with the bearings and air will probably exceed it by far.
>
> Maybe you can also drive it with compressed air. There are air
> grinders that run pretty fast, if you add a small turbine on the top
> of your spindle that may work, but will be very loud.
Here's an inexpensive one:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?itemnumber=47869&Submit=GoWalt.
>
> ST
>
>
> On Wed, Jan 21, 2009 at 9:05 PM, Simao Cardoso <simaocardoso@...> wrote:
> >
> > It's a good thing but, I am surprised by quantity of professional, and
> > experienced reply on a Homebrew named list...
> >
> > If would buy a already made machine if wish a really good one.
It's just
> > an hobby thing.
> > And as i said my wish is a 30-40.000rpm spindle. I can test if it
handle
> > above that but it stops there. This is a cheaper dremel like
tool, but
> > it can go faster or make less noise for the same rpm and have
> > replaceable bearings (they came in a box of 10), and maybe a
better tool
> > chuck.
> >
> > My questions related to use of DC with pwm on and AC brushed motor, or
> > where to post it on cnczone, didn't deserve answer like a balance
> > machine did.
> >
>