Messages

31

FAQs / Re: Losing steps or something?

« on: November 01, 2010, 05:43:12 AM »

Hi, Roger.  Shaking back and forth like the program calls for, basically.  But with the added offsetting.
A storage scope and a way to count the steps would be way cool, but I don't have access to one.  Oh, well.
I have been using constant velocity mode.  I'll check that out tomorrow, along with the pause idea.
I did, however, get the Larken Viper 200 servo drive and Ametek motor with a 500 line (2000 count) encoder hooked up.  It only accepts +5V common signals, so I had to use the PMDX breakout board.  I put an index mark on the sproket that is on this motor and an indicator so I can see if it offsets.  Yup.  It seems to be doing the same things the stepper system does.  The PMDX BOB has an activity LED that flashes when pulses are flowing.  It seems to flicker in time with the stuttering/pulsing of the tests I ran.  I haven't gotten to run all the tests but at .00015 it walked over to its new offset just like the stepper motor system did. 
I'll report back soon.  Curiosity...  OCX driver test - what should I be looking for when running it.  It had very small vertical lines in the graphical display when I ran it when I put the computer into service... 
Don

Dan, Good to hear from you.  It might be a combination of things, but I'm starting to wonder about software/pc issues...  Changing out the entire Drive system with the exception of the power supply seems not to cure anything.
Don

32

FAQs / Re: Losing steps or something?

« on: November 01, 2010, 12:43:33 AM »

The strange-ness gets stranger...  I set line 5 of the test program to X-.00015 with the loop set to 100 repetitions, ran the program, and it walked over to -.011...
I set the loop to 500 and ran it again and it walks right over to -.055.
Then I set line 5 to X+.0004 and the x axis buzzed over -.102 total after running the program 10 times.  I set the Loop to 500 reps and ran that twice - offset totaled -.100.
Then I set line 5 to X+.0005 and Loop 100 reps, and the x axis buzzes and moves over +.001 after 10 runs of the program.  After running the program 20 times the offset was +.002.  Yeah.  Positive direction this time.
I set the Line 5 to X+.0006 and in 10 runs of the program, it buzzes with a rapid ticking or pulsing of the sound of the drive system - about 10 pulses in the duration of the program, and offsets about .001 per 100 reps...
I set line 5 to X+.0010.  Very loud vibratory buzz with about 10 cyclical pulses to the sound, but after running this program 10+ times, there is still NO discernable Offset!!!
I set line 5 to X+.002 .  Very loud with 5 initial loud pulses then smoother for the rest of the "run".  No discernable offset despite multiple runs of the program.  Just nasty buzzing.
I changed the loop to 500 reps.
X+.001 buzzes but does not offset.  sound has 9 pulsed and then smooth buzzing...  I ran this multiple times with no offsetting.
X+.00015 machine walks right over to -.055". Aargh!
X+.010 table jiggles like a paint shaker and offsets - get this! - -.050".  
     I am truly bewildered... Don

33

FAQs / Re: Losing steps or something?

« on: October 31, 2010, 08:15:20 PM »

So do I. 
I just completed purging the old Mach3 install.  I installed the Current Lockdown version.  Downloaded onto this computer, burned a CD, took CD to shop, installed it into milling machine.  No license installed yet.  I've configured the axes and run the x-axis test program.  Now the darn thing offsets to the minus direction!!!  Yup, -.005" in 50 repetitions.  I gotta go to dinner.  I want to try the same tests as earlier today ie. short travel, 100 reps, etc to see if the behavior is consistent when I fire it up later tonight.  I feel like I'm in the "Twilight Zone"...  Don 

34

FAQs / Re: Losing steps or something?

« on: October 31, 2010, 06:51:37 PM »

Hi, Roger.  I just uninstalled the Mach software and am cleaning out the computer to make sure it is ALL gone.  Then I'm going to download a new copy and install it.  Without the license file, at first.  If that doesn't fix it, I have one other card in my hat.  I have a couple of Larken Automation Viper 200 servo drives and an Ametek servo motor that I'll try to set up to see if it repeats any differently.  I know it could open another whole can of worms, but It might be worth a try.  Thanks for the help so far.  Don

35

FAQs / Re: Losing steps or something?

« on: October 31, 2010, 05:33:08 PM »

I have tried some other tests over the last fw days.  adjusting the Motor Tuning step pulse numbers from 0us to 15 us has no effect.  changing the dir between 0 and 5 us has no effect.  I've tried several grounding and shielding schemes but no change in behavior is detected.  Hmmm.

36

FAQs / Re: Losing steps or something?

« on: October 31, 2010, 05:22:55 PM »

I just ran some more tests. Changing line 5 from G1x+.1 to G1x-.1 does not change the direction of the offset.  it still moves +.
+.005 in 50 repetitions.
+.010 in 100 reps.
I set the line 5 to read G1X+.00005 and ran the program with the loop set for 100 reps.  No movement was detected at all.  None!.
I set the line 5 for X+.00010 and 100 reps yields +.010 offset.
Set for x-.00010 yields the same +.010 offset.  Hmmm.
Now for the wierd one.
I set the line 5 to read G1X+.00015 and ran the 100 reps.  the offset looked like almost .0110"!!!
So I ran it again and again - a total of 10 times.  Offset is .110 total.
When it runs the program, the movement sounds sort of stuttery, unlike when it is actually moving some distance. 

37

FAQs / Re: Losing steps or something?

« on: October 31, 2010, 04:34:01 PM »

Current setup with only the X axis hooked up.   

38

FAQs / Re: Losing steps or something?

« on: October 31, 2010, 04:29:06 PM »

Hi, Roger.  The steps per unit on my machine is 20000.  5 thread per inch ball screws.  1:2 reduction belt drives.  200 steps per revolution motors.  10 microstep settings on Gecko G212 drives.  Single step resolution of the machine is theoretically .00005"  of course the mechanicals aren't that precise.  My tests of "backlash" have shown about .0003" or so. 
I'm getting a consistent "overshoot" on the way back to Zero such that it returns beyond 0.000.  Each cycle seems to move the offset .0001".  Only by raising the number of iterations can I see it on my machine dials which are calibrated in .001" increments.  If I run the loop 50 times, I get .005 past zero. 100 times, I get .010 past zero.  etc.
I have set the system up with ONLY the x axis connected, the logic set to 0V common, ( so the parallel port can run the drive directly) and with or without the breakout board the result is the same.
I believe this computer is using the current lockdown version of Mach3.  The only thing common to this setup is the license key and the drive system.  I'll try to include a picture of the current setup with my cheater cable. 

39

FAQs / Re: Losing steps or something?

« on: October 29, 2010, 03:52:27 PM »

I've been busy.  I did find that the A-axis gecko exhibits a continuity from the negative power input to chassis.  None of the others does.  Hmmm. 
I removed ALL the wiring for everything and hooked up only the X axis.  I set the gecko and the PMDX BOB to 0V common.  I hooked up only the x-axis signal wires.  I hooked up only the + and - power wires to the x-axis gecko.  I hooked up only the x-axis motor.  There, very simple.  No shields hooked up, just the wiring for the one drive.  I have noticed that the computer MOBO has parallel port shield to chassis continuity, but that doesn't surprise me. 
Result?  Offsetting behavior.  .005" in 50 repititions of the diagonal program.  I started hooking up shields to the power supply negative terminal, all to no avail.  I tried playing with the step and Dir timing in Motor Tuning, trying values from 0 to 15 us but that had no affect either.
I tried to run the x-axis only program and it offsets the same .005" per 50 repetitions also.
This also occurs with my cheater cable feeding the gecko signals directly from the Parallel port.  So, I'm pretty sure the PMDX BOB is not causing any of this. 
With only one axis hooked up, where could the problem be. 

40

FAQs / Re: Losing steps or something?

« on: October 27, 2010, 03:26:08 PM »

I will.  It seems incorrect for there to be a short? or connection to ground that shouldn't be there.  I removed the connector blocks from the Geckos, and then checked from their pins to ground.  The short is not there.  I'll start disconnecting things and testing untill I find something.  Thanks, Don