Marlin stuttering for small circles...
April 22, 2014 05:33AM
I am running a fork of the latest Marlin firmware on my Mendel90. I am generally very pleased with Marlin and the smoothness of motion which translates into high quality prints. One issue though is bothering me - when small circles or tight curves are printed I can hear (and feel) a distinct "stutter" or vibration from the motors. My guess is that the tight curve is a sequence of small segments that are too curved to allow full speed, so Marlin breaks for each vertex and then accellerates again - maybe 20-30 times a second - which shakes the printer. With higher speeds this happens for larger curves as well. The consequence is that the finish is ruined as each stop leads to a slight overdeposition and the acceleration a sligth underdeposition.

Is this a known problem and is there any setting to regulate it - e.g. by filtering out high frequency speed changes?
Re: Marlin stuttering for small circles...
August 14, 2014 04:46PM
did you ever get an answer to this problem?
Re: Marlin stuttering for small circles...
August 16, 2014 05:34AM
Unfortunately no. I think this happens when the jerk limit is reached for tight segmented curves at high speed. In a way the firmware is doing its best. One solution would be to reduce the commanded speed in gcode.
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