Issue with step servo setup - x-axis cutting skewd
19 Jul 2011 23:02 #11662
by crmb
Replied by crmb on topic Re:Issue with step servo setup - x-axis cutting skewd
Please see attached.
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19 Jul 2011 23:32 #11663
by BigJohnT
Replied by BigJohnT on topic Re:Issue with step servo setup - x-axis cutting skewd
I wonder if backlash is valid for a hostmot2 config? I've asked on the IRC...
Does the second axis respond to the backlash setting?
John
Does the second axis respond to the backlash setting?
John
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19 Jul 2011 23:35 #11664
by crmb
Replied by crmb on topic Re:Issue with step servo setup - x-axis cutting skewd
No, the other axis backlash setting isn't working either.
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20 Jul 2011 00:19 #11665
by BigJohnT
Replied by BigJohnT on topic Re:Issue with step servo setup - x-axis cutting skewd
Just to be clear, you set your jog units to 0.001" and jog the axis up to your dial indicator till you see the needle move some then jog the other way and it takes 5 presses till you see the needle move again no matter what backlash compensation you have set for that axis?
I've gotten one answer on the IRC but not sure if it is credible or not. Hopefully Seb or Peter will chime in...
I have one stepper machine using a 5i20 and one servo driven machine with a 5i20 but I don't use backlash compensation on either one so I don't know...
You ini looks fine to me...
John
I've gotten one answer on the IRC but not sure if it is credible or not. Hopefully Seb or Peter will chime in...
I have one stepper machine using a 5i20 and one servo driven machine with a 5i20 but I don't use backlash compensation on either one so I don't know...
You ini looks fine to me...
John
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20 Jul 2011 01:17 #11670
by crmb
Replied by crmb on topic Re:Issue with step servo setup - x-axis cutting skewd
John,
I think the guys were getting confused. I went and tested as you indicated with setting the jog to 0.001, when i changed directions it would swing negative ~0.004 the other way. They had to turned up the backlash way too high. So by zero'ing it out and watching the needle, with backlash = 0, it took basically two jogs to make the axis move 0.001 in the opposite direction of motion. With the correct setting now it seems to be compensating correctly although it still not 100% perfect. I think they were trying to dial it in with too large of a step size or something not sure. I was going to test cut but unfortunately it looks like nitrogen likes to bleed out of bottles, both of our tanks are empty now.
Much appreciated though.
Adam
I think the guys were getting confused. I went and tested as you indicated with setting the jog to 0.001, when i changed directions it would swing negative ~0.004 the other way. They had to turned up the backlash way too high. So by zero'ing it out and watching the needle, with backlash = 0, it took basically two jogs to make the axis move 0.001 in the opposite direction of motion. With the correct setting now it seems to be compensating correctly although it still not 100% perfect. I think they were trying to dial it in with too large of a step size or something not sure. I was going to test cut but unfortunately it looks like nitrogen likes to bleed out of bottles, both of our tanks are empty now.
![:( :(](/media/kunena/emoticons/sad.png)
Adam
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20 Jul 2011 11:01 #11679
by Rick G
Replied by Rick G on topic Re:Issue with step servo setup - x-axis cutting skewd
For what it is worth I use a 5i20 and the backlash comp does work.
To check I use MDI moves.
With the backlash comp off...
First a large negative moves at a slow speed say g1 x-1
Then a positive move g1 x1
I then set my dial indicator at 0
Then a positive move say g1x1.025
Then check that the machine moves .025 to check the scale
If that is OK then g1 x1
Read the dial indicator and any difference from 0 is the backlash for that spot on your machine, it could be different in different locations in which case you may want to look at a compensation table.
Put the backlash comp back on with this number and try again, should be OK now.
Rick G
To check I use MDI moves.
With the backlash comp off...
First a large negative moves at a slow speed say g1 x-1
Then a positive move g1 x1
I then set my dial indicator at 0
Then a positive move say g1x1.025
Then check that the machine moves .025 to check the scale
If that is OK then g1 x1
Read the dial indicator and any difference from 0 is the backlash for that spot on your machine, it could be different in different locations in which case you may want to look at a compensation table.
Put the backlash comp back on with this number and try again, should be OK now.
Rick G
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20 Jul 2011 11:19 #11681
by BigJohnT
Replied by BigJohnT on topic Re:Issue with step servo setup - x-axis cutting skewd
Thanks Rick
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