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.
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.
>