Stepper Tuning

Main Page

After many hours of fiddling with the stepper drive and motors I have some final information for anyone wanting to embark on this project.

I believe I had mentioned the Vexta Steppers (part #    PH266-E1.2 )  that were inexpensively obtained from C&H Sales in California.   The tuning process was long and difficult and worst of all never seemed to get as quiet and most importantly as smooth as it could (should?) be.  I had been in Email contact with Lenord Stage of GOTO Telescopes in Texas and Mel Bartels the creator of this fantastic system.  I also talked via land line to Lenord a few times.  I put about 25 hours into the tuning process before giving up and shipping the computer and drives to Lenord for tuning.   BTW, he charges a reasonable fee for this service so if you have reservations about the project because of this, he will do it for you.  Lenord put about 15 hours into the process before giving up on the Vexta steppers and supplying a replacement set that tuned up quite well.  His take on the problem is mostly steppers and a little bit computer.  For those of you embarking on this project be aware that it is possible to have a bad laptop/drive combination but this is generally quite rare.  I just happened to be the lucky one this time!

The drive is now tuned for 40 ms (microsteps) and will be star tested as soon as the weather cooperates, hopefully tonight (31 May, 03).  All previous tests were done at 20 ms.

The drive has been tested many times since the above was written and has performed flawlessly, with the exception of the noise level.  Several tactics were used to reduce the noise to a very acceptable level.  Check here for more details as they get added.

Stepper System Settings for stupid people (of which I am one in this case).

Settings mentioned here are using a 200 mHz pentium and the Vexta Steppers mentioned above

Slow speed movement (hand pad) "M" on PC, larger is faster, try on a high power eyepiece!
Slew speed (starting slew speed) MaxDelay, larger is slower  1100 is good starting point
Slew speed (top slew speed) MinDelay, larger is slower   500 a starting point
Ramp up time HsRampX, larger is longer  2 or 0 to start

Copyright 1997-2012by Bill VanOrden