Y axis slips  

Eminent Member

Hi All,

Not really a new issue, I have printed many objects before this with the MK2.5S with no problem, but now getting Y axis slips ( again - had it a couple of times before the MK2 to MK2.5S upgrade ).  About 10 mm up, I got 2 slips of about 5mm each on successive layers.  See photos.  Have checked motor grubscrews, belt tension, motor mount, all the obvious things, but nothing mechanical wrong that I can see.  If I use the manual settings to hold the Y axis, cannot move it manually - its locked tight, as I would expect.  And if I turn the power off, the Y axis travels smoothly with normal hand pressure from full foward to back, with no tight spots or any problem.  I am still a bit suspicious of some lurking bug in the stepper motor drivers, but cant seem to pin it down, and its certainly not reproducible.  Any thoughts ?

Posted : 02/08/2020 3:15 am
Eminent Member

One more note:  I have aalways used "silent mode", ie low power.  Will run another print at "high power" to see what happens.  Saw this mentioned by someone else having similar problems.

Posted : 02/08/2020 3:43 am
Active Member

I had Y-axis skipping happening consistently happening on one specific print, it was 160 x 160 x 3 mm with several dozen holes in PETG.  It would pick up and set down hundreds of times, get stuck, then skip the Y belt and break free.  I tried increasing temps to no avail, and then tightened the Y belt 1 tooth, which got me through that print.

Try changing the belt tension by 1 tooth.  If you tend to run tight belts, try 1 tooth looser,  or if you already have the belts nice and loose, try 1 tooth tighter.

Otherwise, maybe one of the linear bearings is acting up from time to time? Possibly a damaged ball or trapped dirt jams it up occasionally?


Good luck!

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Posted : 02/08/2020 4:50 pm
Eminent Member

Thanks for the suggestions.  I would have thought that a belt slip would be by 1 tooth length, ie 2.5 mm, or perhaps a multiple.  Mine are more like 2.3, 4.6 and 8.8 mm.  Belt tension seems good to me.  The bearings and rods are new ones done in the MK2.5S upgrade. Y carriage movement is absolutely smooth over the full travel, so I doubt its dirt or bearing damage. 

Changed the power setting from 'silent' to 'high power'.  Completed 2 prints on the part I had problems with.  Worked perfectly.  Much noisier, but I can live with that.  Will continue with 'high power' setting.

Posted : 03/08/2020 12:09 am

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