Can You Say, "Layer Shifting"?

Yeah, I'd never heard the term before either. Apparently it's a thing with 3D printers.

Well, not a "thing", per se, but more like an affliction. My printer was apparently no exception. As impressive as that first photo looks, the part is not supposed to look that way. The photo below is what the finished part is supposed to look like, and it was my first attempt at making this part. While this first attempt turned out OK, it was a little too loose when installed, so I was making a second piece with a few dimensional tweaks. That's when things went askew........... Did you see what I did there?

So now that I know I need to fix something, the next question is, what is it that I need to fix? The model for the part in both above photos was essentially the same except for the dimensional changes and that for the "shifted" part I used 10% infill, whereas the original part that turned out fine used 100% infill (solid interior).

Not knowing yet what to do differently, I changed the infill from 10% to 30% and tried printing again. Not much changed with the new print except that it now leaned the opposite direction of the first leaning tower.

Pretty impressive overhang, eh?

I had left the first layer-shifted part to print by itself, so I didn't see the drama unfold. For the second layer-shifted part, I hung around until it started doing its funky magic. It was then that I noticed a distinct but quiet *clack* during the start of each new layer of the print cycle and I wondered if maybe something was slipping each time it clacked. I checked the drive wheel on the Y-axis bed servo but it was good and tight. So then I went into the slicer program (Cura) and slowed down travel speed from 120mm/sec to 80mm/sec. I also changed the wall thickness from 1mm to 1.2mm. Both those changes seemed to do the trick, as the new part turned out great, and no clacking.

And the good news is the revised dimensions of the part made it fit perfectly. It slips onto the filament sensor snugly and acts as a guard so that the filament doesn't rub a groove in the aluminum sensor housing. This next photo below shows the filament entering the sensor without the guard in place. I imagine it would take some time for the filament to do any appreciable damage but I thought it was a good challenge to design and build the part.

The above photo shows white filament on a nearly empty roll and the rolling resistance of the lightweight roll is not much, so the filament isn't putting a lot of pressure on the aluminum block, whereas the next photo shows the filament being pulled tight due to a new (and heavier) roll. It'll be interesting to see how well the PLA filament guide holds up.