gael
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Posts: 11
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Post by gael on Dec 26, 2015 14:20:23 GMT
Hi, I have an issue with the Y axis which is drifting Here is the result of the print of the result of the Extrusion_Clip_3.gcode file provided on the SD card Do you see on the bottom right the Y drift of about 1mm at each loop. Here is an other result of a cube print: ( I put the G code of the print as well ) testcube_20mm.gcode.zip (71.92 KB) What could cause the problem? The belt tension seems ok to me. I try with many different tensions from loose to very tight, but the result is the same. I've checked as well if there was no hard point on the bed movement, but there are none. I don't know what could cause this kind on behavior. Do you have any idea of what should I check? Thanks for your your advices, Gael.
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Post by 3DMS on Dec 26, 2015 15:00:15 GMT
When you have a drift on 1 axis you need to check a few things: - Check that the pulley M3 nut is properly tighten, some times it slips a little creating this effect on the axis when performing high acceleration (direction change).
- The stepper motor voltage is too low on this axis and the motor is missing some steps. As you've just adjusted your stepper motor voltage it might come from the voltage being a little too low.
Depending on the A4988 model you have, you will need to adjust the voltage based on RS value.
this article is showing you how to locate RS on the driver and determine the proper voltage. reprap.org/wiki/A4988_vs_DRV8825_Chinese_Stepper_Driver_Boardsthis one give your the math equation to adjust the voltage: reprap.org/wiki/Pololu_stepper_driver_boardIt might be hidden by the heatsinks however, and you might need a glass magnifier to see the value. I tell you this because i happen to have received another shipment of A4988 and the RS value is different. From what i remember yours should be R050 => 0.05 Ohm => 0.3V => 0.75A The one i received are now R100 => 0.10 Ohm => 0.6V => 0.75A The motors are able to withstand 1.2A and from what we can see 0.75A is enough for this kind of application/motor in order to have a good torque and low heat. The one we had on our prototypes were R100. From memory you should have the ones with R050 but you post makes me wonder if maybe you have a mix of both :/ Do you remember this axis being hot previously to your voltage calibration? Does this help?
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gael
New Member
Posts: 11
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Post by gael on Dec 26, 2015 16:01:30 GMT
Hy, My voltage for this stepper motor was a 0.7for the Y motor, after increasing it to 0.9 I've a much better result (at least for the first layer) I'll let my print going further and I'll let you know the result. Thanks for your blasting fast reply Gael.
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Post by 3DMS on Dec 26, 2015 16:07:11 GMT
Also you can try to change this stepper driver with the spare one you should have included in your kit. In rare occasions it happens that some get damaged. Did you use the Ceramic screw driver when adjusting the voltage?
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gael
New Member
Posts: 11
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Post by gael on Dec 26, 2015 16:19:52 GMT
The result is better but it still drift.
I've exchange the stepper motor between X and Y.
I'll see if the problem goes to the X axis or if it stay on the Y axis.
I'll keep you posted.
Gael.
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gael
New Member
Posts: 11
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Post by gael on Dec 26, 2015 16:31:30 GMT
Bingo ! ! ! After exchanging the stepper motor driver between the Y and X axis, the problem have now moved to the X axis.
Maybe the driver have been damage with the over heat of the RAMP. I'll try to replace it with the spare stepper motor driver you provide. Unfortunately I don't have it here at the moment so I'll not be able to test it before a week and half I'll let you know if that resolve the problem. Gael.
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Post by 3DMS on Dec 26, 2015 16:36:10 GMT
Thanks for the feedback! Those stuff can be tricky when they start to become faulty :/ and it's a good thing you could pinpoint the issue this quickly!
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gael
New Member
Posts: 11
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Post by gael on Jan 3, 2016 16:49:55 GMT
After changing the stepper motor driver the printer finally works fine and I manage to print the calibration cube correctly.
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Post by 3DMS on Jan 3, 2016 16:52:13 GMT
Great news, Champagne!
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