circle cutting test fusion

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02 Oct 2021 19:13 - 02 Oct 2021 21:08 #222040 by paulsao
  Could someone give me a hint why the cut of the circle presents some oscillations in some parts, it is not in all.
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Last edit: 02 Oct 2021 21:08 by paulsao.

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02 Oct 2021 21:52 #222053 by chris@cnc
I guess you already adjust the PID many times. But finaly we have only two reason. Mechanic or PID loop. Mechanic could be not straight or parallel linear guides. And servo can not run smooth at this point. 
Its almost in same area, check mechanic there. Its sporadic somewhere, decrease your P term.
I remember you plot good circles on paper. I would do it again to indentify bad areas.
bad game....
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02 Oct 2021 22:29 #222055 by paulsao
Replied by paulsao on topic circle cutting test fusion
Thanks for your help, now I am going to carry out other tests but I have some doubts before:
1) In circles the PID also enters the game? I have P = 25
2) I have carried out some tests and I see that the vibrations occur when the 2 axes come into operation at the same time but right in some corner it smells of something of the acceleration I do not know how to adjust those values. 
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02 Oct 2021 22:33 #222056 by chris@cnc
I forgot to say electromagnetic noise could be also one reason. If all circles ok, look to your cables. This subject is discuss many times.
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02 Oct 2021 22:47 - 02 Oct 2021 22:51 #222058 by chris@cnc

Thanks for your help, now I am going to carry out other tests but I have some doubts before:
1) In circles the PID also enters the game? I have P = 25
2) I have carried out some tests and I see that the vibrations occur when the 2 axes come into operation at the same time but right in some corner it smells of something of the acceleration I do not know how to adjust those values. 

P=25 is not much. Maybe you show your ini file to see all numbers. And what kind of Hardware did you use? And which axis does that? May you have to tune your amplifier gain.
Last edit: 02 Oct 2021 22:51 by chris@cnc. Reason: i wish this preview button back
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02 Oct 2021 23:15 #222060 by paulsao
Replied by paulsao on topic circle cutting test fusion
I am using dm556 drivers with 1/64 microstep divisions, nema 23 motors, the x axis has that problem, coincidentally that axis has a nema 23 motor but different from those of the (y) axis, it consumes more current and is not very quiet, now that I check my stepper motor cable it does not have protection against electromagnetism, I think I will replace that to eliminate all possibilities, I did a test reducing the acceleration and I no longer have the oscillations, but I think it is not good for the thc anymore that it would not reach the desired speeds. I am attaching my ini file.
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02 Oct 2021 23:50 #222064 by chris@cnc
I take a look in your ini.
[AXIS_X]
# set to double the value in the corresponding joint
MAX_VELOCITY = 200.0
# set to double the value in the corresponding joint
MAX_ACCELERATION = 1000
# shares the above two equally between the joint and the offset
OFFSET_AV_RATIO = 0.5
MIN_LIMIT = -1
MAX_LIMIT = 1525.0

[JOINT_0]
TYPE = LINEAR
HOME = 10
FERROR = 10.0
MIN_FERROR = 1.0
MAX_VELOCITY = 100
MAX_ACCELERATION = 500
# The values below should be 25% larger than MAX_VELOCITY and MAX_ACCELERATION
# If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger.
STEPGEN_MAXVEL = 125
STEPGEN_MAXACCEL = 625
P = 1000.0
P = 1000.0 not 25. 
and 
DIRSETUP   = 5000
DIRHOLD    = 10000
STEPLEN    = 2500
STEPSPACE  = 2500
is minimum limit in leadshine manual. Here could you go little longer for test. And last try set Max_Velocity and Max_Acceleration on all joints equal.  They must do all the same... 
 
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03 Oct 2021 16:43 #222119 by paulsao
Replied by paulsao on topic circle cutting test fusion
I managed to correct the vibration error by reducing the acceleration a bit I think it is not very good for the thc but for now I am going to leave it that way, since the only solution is to place a reduction system in the motors and bands system because I have it connected directly and that influences the vibrations, thanks for your time and help.

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07 Oct 2021 20:48 #222485 by Todd Zuercher
I have seen similar vibrations caused by slop in an axis from a worn or maladjusted bearing or loose belt.
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