Strange prusa printing issue

Hey Guys

I hope someone might have seen this before, havent used my prusa in a while and just started again. Using the Marlin firmware, Slicing with slic3r and connecting to the printer with pronterface. The issue I am having is stepping in the print I initially thought a mechanical issue but it is so consistent it will step out for x layers then back in for x layers on the surface of anything I print I have tried a lot of fiddling but I am at a loss as to what is doing this. If anyone has an Idea I would love to hear it.


Cheers

It almost looks like the 3D printer equivalent of "pixelated" - Don't know much about slic3r, but, could this be some sort of "coarseness" setting? if you have a setting for coarseness try setting it to 1.0, other than that, I have no idea sorry!

... could be your Z-steps per layer height were different? - if reducing the layer-height with same extruding values, the plastc is more 'squished' and will extend the outer dimension slightly ... same with higher layers forming smaller outline dimensions ...

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The interesting thing is though it is always the same I would assume if it were mehanical it would affect all layers, however the layer which stick out are stacked perfectly it really seems on purpose.

Does the spacing of the wobble line up with the threads on your Z Screw?

Very good thinking I will check that , I dont think it wil be though because the steps go all the way around the print. were if it were a missalignment issue it would be stepped on one side and not on the other.

Depends how bad the wobble is, it can certainly go all the way around the print.

the infamous 'Z-Wobble' would NOT do this in a print, no matter how bad it is.

Z-wobble would shift the layer to one side but NOT overhang a complete layer all the way around the perimeter.

Layer smash maybe, but not wobble.

What kind of couplers are you running on your Z-axis? Z motors on top or bottom of your printer?

It looks like your couplers are torque/spring loading and unloading during printing. The entire x-axis assembly weight is carried by the Z axis lead screws.

Running aluminum couplers on mine, motors on top, with 608 bearings and nuts on the bottom of the rods so that the x assembly is not hanging on the couplers. Very sure these couplers would snap in a day if they were holding up the weight of the x axis assembly.

Edited 4 time(s). Last edit at 12/10/2012 06:48PM by Dirty Steve.