RE: [CAD_CAM_EDM_DRO] Re: Why is my feedrate slow with stepper motor

Hi, Roger:

Akron, eh.... We're practically neighbors.

Start out with your config.sys file and comment out each line, one line at a
time. Observe the waveshape to find what drivers are sucking time during the
clock interrupt. EMM386.EXE is a good start. But, there may be others.

As far as a faster computer - yes, it'll help because it'll execute the
suckers faster. But, I'm successfully using a 50 mhz CPU / 25 mhz bus system
and am capable of running speeds around nineteen inches per minute. I'm
using Sherline equipment, and the 20 tpi leadscrew accounts for some of the
lack of speed compared to the 5 tpi leadscrews that some of the larger CNC
machines use.

My advice - clean up your pulse train stability. Depending on your idea of
"proper" speed, this may be enough (my guess is that it won't be). Next,
increase the power supply voltage and add some resistance in series with the
motor windings. Calculate the series resistance by dividing the difference
between power supply voltage and motor voltage by the desired current. The
power rating of the resistors is I*I*R. If possible, use noninductive
resistors. I don't know what, if any, surplus places Akron has, but you
might want to take a ride to Electronic Surplus on Broadway in Cleveland.
They should have a selection of resistors. Next, you might want to try
either the Camtronics 2Amp driver kit or the Gecko drives (or similar
bipolar drives).

-- Jerry


|-----Original Message-----
|From: lenskeeper2000 [mailto:rnichol1@...]
|Sent: Saturday, March 23, 2002 9:03 AM
|To: CAD_CAM_EDM_DRO@yahoogroups.com
|Subject: [CAD_CAM_EDM_DRO] Re: Why is my feedrate slow with stepper
|motor
|
|
|I think the hitch in my data stream is what I need to clean up first
|as it could derail any other improvements. I put an old ocilloscope
|on the timing puls to the driver and can see the hitch - shows up as
|a reversal in the wave pattern every so often.
|
|would a faster computer help? I've tried 133 and 200 Mhz pc's but
|maybe these are still to slow to overcome interrupt delays.
|
|Roger N
|Akron OH