Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
wrote:
>
> Richard wrote:
> 
> 
> > Buy one decent spindle, and be done with the problem
> > forever.  But the market is probably too small for anyone
> > to make such a thing; especially if nobody is willing to
> > spend more than $39.
> 
> There seems to be the conventional electric die grinders at < US$150, 
> and the > $2000 specialized CNC PCB drilling spinals, like those
made by 
> Westwind. There is nothing in between. As you say the PCB hobbyist 
> market is too small and I guess no one needs a 30000+ RPM electric
die grinder. 

Well, I had never heard the term "die grinder" before reading this
thread.     A quick google search reveals that inexpensive electric
die grinders run from 19000 to 27000rpm.   I just bought a Proxxon
professional grinder IB/E rotary tool for $109, including shipping.  
Some die grinders cost less; some cost more.   One thing I noticed is
they all weigh more --some weigh twice as much as the Proxxon rotary
tool; some weigh four times as much.

Check out the die grinders here: 
http://www.mytoolstore.com/makita/mak08-08.html

I am guessing the weight would not be a factor if you use some kind of
balanced drill press.   But it would be a factor if you plan to use
the tool in your hand.

Another factor is speed control.   Do the die grinders have a variable
speed that you set with a rotary control like on the Proxxon?   Or is
it all open-loop that runs the motor as fast as possible until it's
loaded?

Another factor is collet sizes.   The die grinders seem to have a
single bit diameter; the Proxxon has six different diameters.

Is there an advantage to having speeds exceeding 30000rpm?