Strange Z axis behaviour
21 Mar 2018 21:36 #107700
by aaron
Strange Z axis behaviour was created by aaron
Hi
I have just added a rotary axis to my xyzx CNC router (I have 2 steppers running the x axis).
The rotary axis worked well before I added the second X axis motor, but now the z axis is acting strangely. Every time the machine makes a rapid move and then plunges into the job it goes a mm deeper, so after 10 rapids and plunges the cutter is about 10mm deeper than it should be. I have checked the .ini and .hal files, but can't find a problem. The same file works well on a 3 axis configuration. Can anyone tell me why this is happening?
Thanks
Aaron
I have just added a rotary axis to my xyzx CNC router (I have 2 steppers running the x axis).
The rotary axis worked well before I added the second X axis motor, but now the z axis is acting strangely. Every time the machine makes a rapid move and then plunges into the job it goes a mm deeper, so after 10 rapids and plunges the cutter is about 10mm deeper than it should be. I have checked the .ini and .hal files, but can't find a problem. The same file works well on a 3 axis configuration. Can anyone tell me why this is happening?
Thanks
Aaron
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22 Mar 2018 02:19 #107707
by Todd Zuercher
Replied by Todd Zuercher on topic Strange Z axis behaviour
If you share your new and old ini files we can look for anything obvious.
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22 Mar 2018 08:02 #107712
by rodw
Replied by rodw on topic Strange Z axis behaviour
To me it sounds like missing steps on up travel with the force of gravity against the stepper. But why is another story. The only thing I can think of is if your power supply can't provide enough current to feed 2 steppers at the same time the amount of torque is limited by lack of current.
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22 Mar 2018 08:20 #107713
by aaron
Replied by aaron on topic Strange Z axis behaviour
Thanks for you answer.
Is there any way I can test this, what if I reduce speed and acceleration? It seems odd because each stepper/driver has its own power supply.
Is there any way I can test this, what if I reduce speed and acceleration? It seems odd because each stepper/driver has its own power supply.
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22 Mar 2018 08:28 #107714
by rodw
Replied by rodw on topic Strange Z axis behaviour
Try halving your acceleration. Still strange if it used to work.
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31 Mar 2018 08:16 #108165
by aaron
Replied by aaron on topic Strange Z axis behaviour
Hi rodw
Sorry I should have got back to you earlier. You hit the nail right on the head. I reduced speed and acceleration and I got the job done. So thank you very much. However it was running very slowly and I would like it to work at the original speed. Could I ask you to look at the two ini files, the original xxyz and the xxyza please, just to see if I have overlooked something?
Kindest regards
Aaron
Sorry I should have got back to you earlier. You hit the nail right on the head. I reduced speed and acceleration and I got the job done. So thank you very much. However it was running very slowly and I would like it to work at the original speed. Could I ask you to look at the two ini files, the original xxyz and the xxyza please, just to see if I have overlooked something?
Kindest regards
Aaron
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31 Mar 2018 20:16 #108186
by DanMN
Replied by DanMN on topic Strange Z axis behaviour
I'm not sure if it's the cause of your speed problem, but the recommendations for STEPGEN_MAXACCEL is MAX_ACCELERATION + 25%
You might want to bump it up a tad:
MAX_ACCELERATION = 380.0
STEPGEN_MAXACCEL = 475.0
You might want to bump it up a tad:
MAX_ACCELERATION = 380.0
STEPGEN_MAXACCEL = 475.0
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