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Re: Progressive Move Error with X and Y
« Reply #30 on: July 08, 2008, 04:43:36 PM »
Chip,

OK, so it sounds like this is not a recommended configuration since the drivers and the breakout board are both opto-isolated correct?  If that's the case, I will need to bypass the breakout board to eliminate this variable.

Best Regards.

Carl

Offline Hood

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Re: Progressive Move Error with X and Y
« Reply #31 on: July 08, 2008, 04:53:12 PM »
Shouldnt really cause a problem, my mill has an opto BOB and uses Geckos and its fine. Not saying that isnt the problem however so its worth a try connecting direct to the drives. Just watch you have it connected correctly ;)

Hood

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Re: Progressive Move Error with X and Y
« Reply #32 on: July 08, 2008, 11:43:26 PM »
Hi Carl,
You got me stumped. Printed and read this post numerous times looking for a missing clue. What bugs me is the amount you are out and how it's varying. If the board elimination works you can forget these as I'm streching a little. I assume your motor is direct coupled to the screw.

MECHANICAL - Can you confirm that your motor to screw coupling is tight / not slipping?

SOFTWARE - Did you ever consider trying a later version of MACH?
                   Maybe somebody else can answer this question. Is there something in MACH like a home setting, etc
                   not apparent that could contribute to this? Maybe a dumb question but just thinking.
TUNING - Drop your velocity to say 10 IPM, adjust ramp for say 1/3 ramp up, 1/3 vel, 1/3 ramp down relative to time.
              Don't use the Z axis during any of your  x-y testing moves ( and just for kicks, set it just like the X & Y axis ).
              Maybe you want to try upping the current setting on your drives up one amp.

PS: Didn't see anthing wrong with the file you posted, the quadrants are symetrical about the CL's, ran it. PLayed around with my mill and couldn't duplicate what's happening to you.

Just some thoughts and back to the sidelines.
RICH

             
 


Re: Progressive Move Error with X and Y
« Reply #33 on: July 09, 2008, 07:53:22 PM »
RICH,

Thanks for the ideas.  I installed the older R2.61 version but got the same results.  I may try something like R2.58 tomorrow just for kicks.  Took the covers off the pulleys and checked each pulley to ensure they were not slipping and everything seems nice and tight so I believe there's no problem there.

I also ran a test setting the motors to 10IPM and 0.2 acceleration and got the same results.  My first test I repeated 15 times runing the simple program
G1F10
X1Y1
X0Y0

and the results, where the x and y column are thousands off, were:

Cycle   x   y
-----  --  --
 1      0   0
 2      3   3
 3      6   6
 4      8   7
 5     11   9
 6     13  11
 7     15  14
 8     18  14
 9     19  15
10     24  18
11     24  18
12     26  20
13     29  21
14     31  22
15     34  24

So I have some type of cummulative error.  I then did the following test on just the x axis:

G1F10
X1
X0

I ran that 12 times and the dial indicator was exactly on each time.  No variation at all.

I then did:

G1F10
Y1
Y0

I ran that 12 times and the dial indicator was exactly on each time also.

Very puzzling for me.  My next steps include:

1. Bypass breakout board.  I have a new parrallel cable on order so will do that when it arrives.
2. Borrow PC and try a desktop PC instead of the laptop.  Still looking for a loaner.
3. Gear down.  I ordered a 20 tooth and 60 tooth MXL pulley and will try to gear this down as recommended.  Not sure if this will work due to my current configuration but the advice made sense so it's worth trying.
4. Try recommendations that come in from the form.

Thanks again everyone.  It's greatly appreciated.

Best Regards.

Carl

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Re: Progressive Move Error with X and Y
« Reply #34 on: July 09, 2008, 08:07:48 PM »
THere was a similar(not exact) instance over on the Yahoo site. It ended up being the LPT port had a bad voltage component. Might want to check the voltage on the lpt output HIGH and LOW.

Just a thought, (;-) TP

Offline Chaoticone

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Re: Progressive Move Error with X and Y
« Reply #35 on: July 09, 2008, 09:03:26 PM »
All of the info so far certainly suggest skipped steps or a repetetive mechanical slip. How exactly are the srews driven by the motors? I think your headed in the right direction as of now with trying another PC. Keep us posted and we'll keep at it till this one is hammered out. Man made it, Man can fix it.  ;)

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Progressive Move Error with X and Y
« Reply #36 on: July 09, 2008, 09:20:13 PM »
Brett,

The screws are belt driven using 1 to 1 pulleys.  They are the XL series pulleys and belts.  The error is always cummulative in the same direction so I think I can rule out slipage.  In addition, I pulled the covers and twisted and pulled on the pulleys and there was no movement.

I just ran another test at 40IPM acceleration at 1 that repeated the following lines about 100 times and it was right on the money with dial indicators on both axis.

X1
X0
Y1
Y0

I'm also checking the wiring to see if I have any inductive coupling.  I may wire some test cables to bring the cables out of the top of the box from the gecko's and go direct to the drives to see if anything is going on there too.

I'll keep you posted and thanks again for the great support.

Best Regards.

Carl

Offline RICH

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Re: Progressive Move Error with X and Y
« Reply #37 on: July 09, 2008, 10:32:48 PM »
CARL,
I agree with Brett and others.

You can get bombarded with so many questions and suggestions. So sometimes it's easier to find and eliminate a problem by eliminating major pieces of the system. And then homing in on that piece.
 
- Check out the mechanics of the machine and if things look right then move on.
  I don't know what you have there.
 
- Try a different PC - maybe also a newer version of the software ( that's two major related pieces )

- Eliminate BOB

- That leaves the controller

And try doing only one thing at a time.

RICH


 





 

Offline Hood

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Re: Progressive Move Error with X and Y
« Reply #38 on: July 10, 2008, 02:52:39 AM »
What drives do you have?

Hood
Re: Progressive Move Error with X and Y
« Reply #39 on: July 14, 2008, 06:52:42 PM »
Hood,

I have Nema34 Steppers (720 oz/in) on the x and y axis and a Nema23 Stepper (370 oz/in) on the Z axis.

I made test cables so I can bring them directly out of the top of my box to the drives.  My first test was promising.  I ran the following code where lines 3 through 6 reapted 10 times:

G01
F20
X-3Y-1.5
X3
Y2
X0Y0

After cycling 10 times, there was no deviation when returning to the final X0Y0.  I was very pleased and thought I had finally cracked this nut.  So I decided to do some more testing.  This time I only added 1 additional line so on the second test lines 3 through 7 repeated:

G01
F20
X-3Y-1.5
X3
Y2
X-1Y-2
X0Y0

After cycling 10 times, there was a deviation of 0.060 when returning to the final X0Y0.  Why would this one line cause things to fail?  What am I missing that makes this error?

Any suggestions would be greatly appreciated.

Best Regards.

Carl