Layer gaps

Hey,

I´m attacking some more detailed quality issues now and I have these weird layer gaps



When I print single walled object the layer stack very good upon each other and I have no complaints, but when I print solid with 2 shells, I get these gaps, not always a regular as on this pic, but they are always there.

I don´t tink its skipped steps because even in this model here the edges are fine, just on longer straight paths I get them.

Any ideas

What is your lead screw pitch, and layer height?

Check the Reprap Calculator and see if you can tune in the layer height to match more closely the pitch of the Z-screws. Also might want to leave the Z-axis enabled all the time.

It could also be Z-wobble, from the coupling of the lead scres to the motors, but it;s hard to say without seeing it.

The layerheight is already adjusted to the data from prusa´s calculator and I just printed a new coupling, the old one was to big on one side anyway. Although thinking about it would a coupler problem manifest throughout the layer and not just on longer lines. The edges dont seem to be effected.

And I disabled "const bool DISABLE_Z = false;" I always thought it was false all the time. Lets see if that does anything.

Thanks for the tips.

When the pattern is repeating like that in the picture, the lead screws are suspect because they introduce this type of periodicity as they slowly turn. Usually it happens because the coupling, M5 to M8, is slightly off-center on the M8 side. The cheaper flex couplings found on eBay, and printed ones are susceptible to this. If you have metric lead screws, say M8, you can add one of the many 608 skate bearing solutions to your build, and it may help. It does not do much for 5/16", since the fit is loose.

I've had a Prusa Mendel running for several years now on cheap aluminum flex couplings, and initially, I had this type of problem. The things that solved it were liberating the Z stepper motors (no screws or tape holding them on), and replacing one of the lead screws, which was visibly wobbling ever so slightly. It didn't help that I was using 5/16" Imperial threaded rod on an M8 coupling, which is a loose fit.

Aha, how do you implement the bearing solution and how do you liberate the motor I mean it needs something to hold it down?