Hey Guys... I hate to say this, but I fear we are straying from my original question.
I think we might be digressing from the original subject a bit...
I went to the shop today and I stripped Windows XP of all of its extranious bits, as outlined in a Mach-3 document I have.
I tried running my profile, and for abiout three runs, the X-Hand-wheel returned to its starting point and the Z-Handwheel fell four steps short. I thouht things were getting better. Actually, for what I am turning, I could live with jogging "Z" back to zero a few steps and correcting the Z-DRO., but on the fourth try, "Z" fell short by 25 steps... Not acceptable! I tried slowing the motor's max speed settings down from 250 to 200. I don't like the way G0 sounds at 200 mm/Min and the end position never got better.
So, perhaps trimming Windows down is necessary and a good thing, but it hasn't helped getting my tool post to return to its original position.
Then I tried my experimental g-code to run "Z" back & forth several times, then run X back and forth several times. The program moves "Z" from 0 to 128, then back to zero three times at full speed using G0. Then it runs "X" fore & aft from 0 to 128 and back to zero, three times . I tried setting motor speeds at 200, 250, 300, & 350. With each increase in speed the motors sound smoother and get faster and every end run. Every time the script finishes both hand-wheels end back up at zero... every time! Then, I noticed something strange...
As the saddle moves from zero to 128 in either axis, I hear a "glitch" in the motorthat's operating... like it just skipped a step or two. Then on the return from 128 at about two-thirds of the way back (same as 1/3, the way out) , I hear the glitch again. This occurs on both the X-Axis and the "Z"-Axis... wierd! I put a mark beside the rails on each axis. It's like clockwork., When the saddle reaches either mark, from either direction, there is this little "bzzt". The faster the motors are running, the harder the "glitch" is to hear, but nonetheless, it is there.
I wonder if both these motors are skipping pulses every time and the lost pulses in one direction compensate for the same number of lost pulses in the opposite direction. That way, in this situation with one motor running at a time can always return the hand-wheel to zero??
Tell me I'm nuts!
Anybody know of a simple kit to build a TTL pulse-counter with about six digits of display?