gantry motion gets jerky when jogging.

[japco43]

I recently had our cnc router retrofit with camsoft cnc plus. When I jog the gantry, (servo motors Xa and Xb) the gantry starts to move smoothly, and then starts to shake. Its almost like the encoders are loose, and picking up more pulses, than they are supposed to. Maybee the servos are not tuned properly. The outfit that retrofit our unit, never finished the job properly, and tech support from camsoft, has been maybe one question answered in a weeks time. Any ideas how i can smooth out the travel?

[camsoft]

With what you said here it maybe related to the gantry binding. There are several solutions for this.

We need you to call in to proceed. We need ask your dealers name and serial number and to look up what you have.


Tech Support
CamSoft Corp.
support@camsoftcorp.com
PH 951-674-8100
Fax 951-674-3110
www.cnccontrols.com

[Al_The_Man]

I would think that if the integrator used gearing to synchronize the Xa axis as master and Xb slave, you need to make sure that no back lash exists on either master or slave.
Is this a gantry that has a rack and pinion either side?
It could be the gain is set too high on the master side?
Al.

[HillBilly]

It would help to know a few things:

1. Are your servos analog controlled (+/-10v) slaved by the Galil, or are they digital (Step and Direction) with seperate inputs or do they share the same input?

2. Did this problem come with the retrofit or ran fine then appeared later?

Al's advice would pertain to the analog servos with Galil. The digital control can also be in the form of CW/CCW or A/B signals, S/D being the most common. The slaving can also be done with a master axis running either analog or digital and the slave running digital A/B encoder following off the master axis.

[japco43]

The router was manufactured by multicam. serial # MG20442986.
We had this retrofit last year, and the techs never worked out the problems completely, and took about 1 year to do the job, instead of the 2 weeks which was quoted. The gantry never had a problem, before the retrofit. It worked after, but it was never as smooth as before. Now after upgrading to camsoft cncplus version 6.5, It gets real jerky when it reaches jog speed. It doesn't matter if we are going 30 ipm or 250ipm. It seems to be feeding on itself, and accumulating encoder pulses. The other problem we have that still hasn't been addressed is: the Y axis drifts over a little ever time we cycle. After 20 pieces or so they are out of tolerance. We were just drilling a straight line of holes in this example. J.P. Our router has rack and gears for the gantry. Xa and Xb servo motors with motor mounted encoders.

[japco43]

The servo motors that move the gantry, Xa, and Xb were not tuned properly by the people who did our retrofit. They had one motor set at 52.3, and the other set at 23. I, (through trial and error) set them both at 30, and now they move very smooth, at any speed slow, ar fast. J.P.l

[Karl_T]

Originally Posted by japco43 The servo motors that move the gantry, Xa, and Xb were not tuned properly by the people who did our retrofit. They had one motor set at 52.3, and the other set at 23. I, (through trial and error) set them both at 30, and now they move very smooth, at any speed slow, ar fast. J.P.l

CONGRATULATIONS!

It's a great feeling to solve an issue. The tougher the problem, the better you feel when you beat it.

Karl

[nelZ]

I got Camsoft's mid range pendant for my unit - encoder for jogging and 2 buttons - the 600$ one not the USB cheapie. Thanks for them to let me know they just started offering it.

When I use the encoder wheel to move an axis, it is a bit jumpy, not a big problem since I don't cut just position using it. Anybody have had this? I know it's just a setting in the code (overrun limiting?)

Thanks to all.

[Karl_T]

Originally Posted by nelZ I got Camsoft's mid range pendant for my unit - encoder for jogging and 2 buttons - the 600$ one not the USB cheapie. Thanks for them to let me know they just started offering it. When I use the encoder wheel to move an axis, it is a bit jumpy, not a big problem since I don't cut just position using it. Anybody have had this? I know it's just a setting in the code (overrun limiting?) Thanks to all.

I had this on all three machines i've done. Changing RAPIDSPEED and using OK2STOP is the key. Then you got a bit of a mess cause you need to change RAPIDSPEED back when you exit the macro. here's one of my macros - I use coarse and fine on my handwheel.

Karl




'************************************Handwheel*****************************************
[[HANDWHEEL]] 'handwheel jogging code
LOADING \55:IF \55=0 THEN EXIT

IF \140=1 THEN MESSAGE . Start of Handwheel 830= \830

IF \142=1 THEN [GALILERRORS] 'message Galil errors
HANDWHEEL 0
'X axis, #79=0 for large steps
IF\830=5THENIF#79=0THEN RAPIDSPEED 1;1000:HANDWHEEL 1;16;OK2STOP1: GOTO :ENDHANDWHEEL ' SETTING OF 16 GIVES 0.010" PER CLICK z AXIS
IF\830=5THENIF#79=1THEN RAPIDSPEED 1;100:HANDWHEEL 1;800;OK2STOP1: GOTO :ENDHANDWHEEL ' SETTING OF 800 GIVES 0.002" PER CLICK Z AXIS
'Y axis, #79=0 for large steps
IF\830=4THENIF#79=0THEN RAPIDSPEED 2;1000:HANDWHEEL 2;16;OK2STOP1: GOTO :ENDHANDWHEEL ' SETTING OF 16 GIVES 0.010" PER CLICK z AXIS
IF\830=4THENIF#79=1THEN RAPIDSPEED 2;100:HANDWHEEL 2;800;OK2STOP1: GOTO :ENDHANDWHEEL ' SETTING OF 800 GIVES 0.002" PER CLICK Z AXIS
'Z axis, #79=0 for large steps
IF\830=3THENIF#79=0THEN RAPIDSPEED 3;1000:HANDWHEEL 3;16;OK2STOP1: GOTO :ENDHANDWHEEL ' SETTING OF 16 GIVES 0.010" PER CLICK z AXIS
IF\830=3THENIF#79=1THEN RAPIDSPEED 3;100:HANDWHEEL 3;800;OK2STOP1: GOTO :ENDHANDWHEEL ' SETTING OF 800 GIVES 0.002" PER CLICK Z AXIS
'A axis, #79=0 for large steps
IF\830=3THENIF#79=0THEN RAPIDSPEED 4;1000:HANDWHEEL 4;16;OK2STOP1: GOTO :ENDHANDWHEEL ' SETTING OF 16 GIVES 0.010" PER CLICK z AXIS
IF\830=3THENIF#79=1THEN RAPIDSPEED 4;100:HANDWHEEL 4;800;OK2STOP1: GOTO :ENDHANDWHEEL ' SETTING OF 800 GIVES 0.002" PER CLICK Z AXIS

'NOTE rapidspeeds are reduntant in RAPIDPERCENT macro, must change both places
:ENDHANDWHEEL





EDIT I didn't explain setting RAPIDSPEED back


I use a MODE switch to put the machine in HANDWHEEL mode. On exit from the handwheel macro, run a [RAPIDSPEED] macro with these commands:

[[RAPIDPERCENT]]
RAPIDSPEED 1;\129 'assign current rapid speed for X axis
RAPIDSPEED 2;\130 'assign current rapid speed for Y axis

RAPIDSPEED 3;\131 'assign current rapid speed for Z axis
RAPIDSPEED 4;\132 'assign current rapid speed for A axis
'NOTE my maco also uses a multiplier for different rapid %s

also set your RAPIDSPEED in startup.file
\129=20000 'original value of X axis RAPIDSPEED
\130=20000 'original value of Y axis RAPIDSPEED
\131=20000 'original value of Z axis RAPIDSPEED
\132=10000 'original value of A axis RAPIDSPEED

[nelZ]

Thanks, Karl I'll use your example to doctor my file.

Many thanks right from the beginning!

Nelson

[Farmers Machine]

My torch is a gantry with the 3rd axis slaved to the first. the slaved axis always acted goofy. there is a line in the setup.file with 7 parameters that will make the PID on the slave = the PID on the master. IF you dont go in and change the numbers it will default back to the old original and you will always have trouble with the slave. Ernie was the hero on this one.
Good Luck
The Farmer

[davesnd]

I have found that electronic gearing is the best solution for the handwheel - no need to change rapid speeds all around. I, like Karl, have coarse and fine on my handwheel - just different electronic gearing ratios. I noticed in the past that with the camsoft handwheel logic if you turn the handwheel back and forth as fast as you can it gets confused and runs away in one direction. And I HATE having to remember to change rapidspeeds around all the time whenever I edit logic. With the galil commands for electronic gearing this is no longer an issue - it's almost like a real machine now - not jerky and never gets confused not matter how stupid you get playing with the handwheel. I can post the logic for this if anyone is interested.