MJJ56

Search on the forum for "Skipping" https://ultimaker.com/search?search=skipping There are a lot of answers you probable detect a solution. I have the same problems and I think it is a hardware issue in the stepper motor driver chip A4988. I think (but I can't find a description) that the A4988 reverses the direction if the maximum current is reached. I tried the following. Printed a object (small cube) with the maximum current for the E of 1300mA. Result: no problems, no retractions, just fine. Then I lowered the E current to 900mA. With the same g-code: problems, sometimes a rectraction. I great improvement was a new PTFE coupler, skipping was much less but still sometimes skipping. What I dislike most is the fact that I don't know that is "skipping" happened, since I don't stay with the printer all the time Succes, Jaap.

The answer of DaHai8 pushed me towards the A4988. I think (but I can't find a description) that the A4988 reverses the direction if the maximum current is reached. I tried the following. Printed a object (small cube) with the maximum current for the E of 1300mA. Result: no problems, no retractions, just fine. Then I lowered the E current to 900mA. With the same g-code: problems, sometimes a rectraction. So I agree with DaHai8. If I read the datasheet of the A4988 well overheating or maximum current result in the same behavior?? As I said before changing the PTFE coupler had a great positive impact. I even programmed a PTFE used timer in the Marlin firmware, so I know how long I'm using the coupler. What I dislike most is the fact that I don't know that is "skipping" happened, since I don't stay with the printer all the time So DaHai8, sorry, yours answers meant a lot!!

DaHai8, I totally disagree your with your answer. There is NO retraction in the the g-code. Even when the first layer is printed there is a sometimes a retraction. Sometimes printing the brim. See https://ultimaker.com/en/community/16596-retraction-issue there is a video example I found today. If I lower the maximum E-current from 1300mA to a lower value (1000mA) then this retract is far more often. So my conclusion is that the Marlin firmware does this. So your hope that this helps is: NO. My hope is now that you agree with me and/or someone else can help. Anyway thanks for your time and answer though. Regards Jaap.

Hi, When I print a model sometimes there is a unwanted retraction (even when retraction is NOT enabled). There is no reason for the retraction, printing is going very well at that point. My question is: what triggers the retraction. Second: where can I find the code in the Marlin firmware that perform the retraction? I changed the PTFE coupler some weeks ago and I must say the above described perfomance is not noticed anymore. But I wat to know if it happened during a print, because at that point the print is obviously weak. Thanks for an answer, Jaap.

Hi, Changed my version 2.1.1 board today with the electronics used in de the 2.1.4 version. Now I have a silent Ultimaker 2 while not printing! Changed the firmware: Fan on at 40C (EXTRUDER_AUTO_FAN_TEMPERATURE) and turn off at 35C. Otherwise at cooldown around 40C fan goes off and on. Now a hysteresis..... See you, Jaap.