Stepper motor skips one or two steps
May 06, 2014 12:03PM
Hi, i have some minor problems during longer prints, it happens randomly that my stepper motors can happen to skip a step or two while printing, should i maybe lower acceleration in the firmware, and or adjust the pots on the stepper drivers ?
Re: Stepper motor skips one or two steps
May 06, 2014 12:44PM
Both can help, i would try adjusting the current on the driver first.


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Re: Stepper motor skips one or two steps
May 06, 2014 12:46PM
OK - I assume the procedure is just to turn the pot until the motor spasses out, 1/8th the opposite way, and maybe a little more to be sure, correct ?

Edited 1 time(s). Last edit at 05/06/2014 12:46PM by borupdk.
Re: Stepper motor skips one or two steps
May 06, 2014 01:54PM
That would be eyeballing it, which worked ok for me pretty often, but you can also do it properly using an amperemeter. Check the search on this forum, this has been discussed many times by people more knowledgable than me on this.
Cheers
Björn


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: Stepper motor skips one or two steps
May 07, 2014 04:52AM
Increasing stepper current raises torque. If step losses happen only occasionally it's an indication torque is sufficient, so more likely reducing acceleration helps. My guess is, though, jerk values are too high.


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Re: Stepper motor skips one or two steps
May 07, 2014 06:16AM
OK - I lowered the jerk rate and acceleration, i also set the reference voltage on my 4988 drivers to 0.38V, now it seems to run perfectly, although i have some problems with the plastic in the perimeters tend to warp inwards, i suspect it's because during this print i was sitting near a rather cold window, so the plastic might have cooled off too quickly. I have attached a couple of pictures, the first one shows the warping near the edges, the second one shows the end product, im pretty pleased with it so far, considering this is my 5th print overall on the printer.
Attachments:
open | download - IMG_20140507_115918_opt.jpg (136.9 KB)
open | download - IMG_20140507_115929_opt (1).jpg (118.6 KB)
Re: Stepper motor skips one or two steps
June 01, 2014 12:00AM
Hi borupdk, did you fix your warping perimeters? I am experienceing a similar issue.
Re: Stepper motor skips one or two steps
June 02, 2014 10:54AM
Sadly no, but i see the extend of the problem increases when i lower the temperature of the heated bed
Re: Stepper motor skips one or two steps
June 03, 2014 05:16PM
The photos to me kinda looks like it's extruding too much plastic.... and/or there is a lot of wobble of the head as it goes up the z.

I'm also wondering what others thing.... could the skipping in steps be caused by the electronics overheating... and that is why it was happening on longer prints? Turning down the current would help avoid the heat issue, but a fan on the electronics might too I think.

I ask cause I'm having skipping issues right now too.
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