On 05/21/2010 12:31 PM, Winston wrote:
On 5/21/2010 11:17 AM, Joe AutoDrill wrote:

(...)

The forward stroke is our unit so we can do whatever is needed... It's
essentially an air cylinder so we are at the mercy of exhaust rates,
but it
can be / has been done to some degree already.

Pneumatic modulator in parallel with your control valve?
Test by removing the reed valve from a small compressor
and close it's intake port. (It'll play hell with your
closed loop position feedback circuit though.)

That's kind of what I was thinking, only I didn't realize that there was
an off the shelf chingus you could go buy.

If you have a way of knowing when you're actually drilling, don't start
modulating the pressure until you're in contact. Then modulate it such
that the drill never retracts -- just eases up enough to break the chips.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com