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Artifact won't go away

Posted by srs5694 
Artifact won't go away
November 22, 2018 10:20AM
I've been experiencing a problem with my built-from-scratch Kossel XL recently:

The artifacting around the stern of the port side of the Benchy looks like a speed-related ringing artifact, but it's new. The Benchy shown above is printed from the same file that's produced perfect prints in the past. Also, weirdly, the motion of the print head on this surface is from the bow to the stern (left to right in the photo), so they don't seem to be the effect of the print head turning the corner. The problem occurs on a surface that almost, but not quite, faces my Z column. (Ignore the odd color changes; I printed using color-shifting PLA that was exposed to light for too long, so parts of the green are turning grey. The same problem occurs when I use other filaments, though.) The other side of the Benchy is much better, although it's got a couple of more minor artifacts.

I've also tried printing a triangular chip. When it's oriented so that each of its sides directly faces a column, there's no problem. When I rotate it 10 degrees counterclockwise, the problem occurs on the side that faces toward the Z column. (I haven't tried rotating it clockwise.) There's some very faint ringing on the surface that faces the Y column, and the one that faces the X column is perfect.

For unrelated reasons, I replaced my carriage and slider recently, and that didn't help. Likewise for replacing the idler pulleys in each top vertex. I've tried both tightening and loosening my belts, with no effect. I've ensured that every screw related to motion is tight -- those holding my magnetic balls on the carriage and on the effector, everything on my hot end, etc. Slowing down the print to about half speed seems to help (I normally print at 70-100mm/s), but as I said, it printed fine at full speed just a few days ago.

At this point, I'm scraping the bottom of the barrel for ideas -- I'm left with a failing motor and a stretched or otherwise damaged belt. Can anybody suggest a likely culprit, or additional tests to help diagnose the problem?

Edited 1 time(s). Last edit at 11/22/2018 11:05AM by srs5694.
Re: Artifact won't go away
November 22, 2018 11:20AM
My guess is that one of your carriage sliders is sticking instead of moving smoothly when driven by the belt.

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Artifact won't go away
December 08, 2018 10:11PM
Thanks for the suggestion, dc42. It took me a while to do anything with this, and then I didn't get back to post a follow-up, but I think you were right. I cleaned and re-lubricated the sliders and it's much better now.
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