No movement on one axis

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13 Mar 2011 21:29 #7788 by piasdom
Replied by piasdom on topic Re:No movement on one axis
in your example, for X and Y. is that 150,000 or just one hundred fifty? i have stepper motors and the ini was always set at 12,000 and 10,000. so it can
be a lot lower, as in one hundred fifty? so there is no "range", each machine needs to be tested for best results. and i think you are tight about Z and
gravity, i just changed the leadscrew so i may be a little tighter. i didn't realize they(XYZ) could be differant until today. it makes sence :)
Thanks

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13 Mar 2011 22:55 #7793 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
Yea mine is 150 and it is an inch machine and my scale is 3800 for the X axis.

From the integrators manual:

MAX_ACCELERATION Maximum acceleration for this axis in machine units per second squared.


So depending on your scale and machine units and all the other things we talked about a sane maximum acceleration can be picked and tried.

The scale will determine the rpm of the stepper at max velocity. So in the case of my Z the scale is 20,000 it has to rev up a lot to move an inch where as my X and Y don't. I wish I could explain this better but words fail me atm. The main thing is to be able to reverse and axis at maximum velocity without loosing steps. This is the reason for the stepper test to do just that.

John

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13 Mar 2011 23:11 #7794 by piasdom
Replied by piasdom on topic Re:No movement on one axis
my scale is16,000 and an inch leadscrew as well. thanks for explaining.
i'll start with STEPGEN_MAXACCEL = 20,000 and my MAX_ACCELERATION = 19,000.
should i keep the STEPGEN_MAXACCEL at 20,000 and adjust MAX_ACCELERATION during testing?
or is it best the other way ? adjust STEPGEN_MAXACCEL . and the greater the distants between the two amounts give the
motor time to change direction ?

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13 Mar 2011 23:19 #7795 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
The STEPGEN_MAXACCEL is to give stepgen some headroom so it to "keep up" with direction reversals when you have backlash enabled. So the ratio should always be in the range shown in the manual.

John

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13 Mar 2011 23:25 - 13 Mar 2011 23:26 #7797 by piasdom
Replied by piasdom on topic Re:No movement on one axis
i understand the percentage limits, but didn't know which i should adjust while testing.
leave the STEPGEN_MAXACCEL at 20,000 and adjust the MAX_ACCELERATION within that percentage limit or
leave the MAX_ACCELERATION at 19,000 and adjust the STEPGEN_MAXACCEL within the limit. i have no backlash at
the moment. so it would be within the 1% to 10% adjustment. i don't think adjusting BOTH at the same will help me.

"STEPGEN_MAXACCEL should be 1% to 10% larger than the axis MAX_ACCELERATION.
If you have added backlash compensation to an axis then this should be 1.5 to 2 times greater than MAX_ACCELERATION."
Last edit: 13 Mar 2011 23:26 by piasdom.

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13 Mar 2011 23:48 #7798 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
They do different things so without backlash enabled just keep it at 1%.

John

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14 Mar 2011 00:19 #7799 by piasdom
Replied by piasdom on topic Re:No movement on one axis
cool Thanks

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15 Mar 2011 13:34 #7854 by piasdom
Replied by piasdom on topic Re:No movement on one axis
that was my mistake. i thought the 12.000 and 10.000 had a comma not a period :)
so i have 12 and 10 :) but i had this ini file for a few months now. and i noticed it had MAX_ACCELERATION was 10
and STEPGEN_MAXACCEL was 12. that's backwards. and i never had trouble till i changed the lead screw. i now have
STEPGEN_MAXACCEL 20 and MAX_ACCELERATION 15 and continuing to test.



BigJohnT wrote:

Yea mine is 150 and it is an inch machine and my scale is 3800 for the X axis.

From the integrators manual:

MAX_ACCELERATION Maximum acceleration for this axis in machine units per second squared.


So depending on your scale and machine units and all the other things we talked about a sane maximum acceleration can be picked and tried.

The scale will determine the rpm of the stepper at max velocity. So in the case of my Z the scale is 20,000 it has to rev up a lot to move an inch where as my X and Y don't. I wish I could explain this better but words fail me atm. The main thing is to be able to reverse and axis at maximum velocity without loosing steps. This is the reason for the stepper test to do just that.

John

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15 Mar 2011 15:23 #7857 by piasdom
Replied by piasdom on topic Re:No movement on one axis
testing at 10, 20, 30 40 and now 50 MAX_ACCELERATION and keeping STEPGEN_MAXACCEL 1.5 (enabled backlash) above that.
do i keep going till i get fellow errors ? or whatever error this will cause. i know this works, but how do i know where it's a good
range for my steppers ?

currently;
MAX_ACCELERATION = 50
STEPGEN_MAXACCEL =75

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15 Mar 2011 16:28 #7858 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
Well, you can go till it is fast enough changing directions or the stepper stalls out or you start loosing steps. In the latter case you will want to back down after you find the limit.

John

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