Y-Shift 68mm from Bottom (could this be a toothed belt skip?)
Hi All,
I printed yesterday a PSU replacement brace (to move PSU out of box later on...)
(This one https://www.prusaprinters.org/prints/994-mk3-delta-psu-support-bracket )
About 68mm from Bottom there is a shift (maybee 0.2mm; you can see and feel it, see pictures..)
I have crosschecked tha STL model. This is definitively an artifact by printer.
Any idea what might cause this?
* too loose Y-belt and maybee some PETG drop that caused a collision next round and this causing a jump over a tooth?
Shouldn't it be more if the belt jumped (considering the tooth pitch)?
* more likely the step motor lost a step then?
*Vibration?
* Octoprint influence (I do not think so), but yesterday installed Telegram plugin, used a few times for status query from abroad...
Any ideas, suggestions, similar effects seen?
Thx for any comment!
ckranich
RE: Y-Shift 68mm from Bottom (could this be a toothed belt skip?)
You sure this is not a X axis shift?
Going on the assumption it is X, move the extruder from one side to the other.
Is it smooth, or does it bind in spots?
If it binds, try loosening the 5 screws that clamp the X bearing in. Maybe 1/4 - 1/2 turn each.
Make sure your bearings are well lubricated too.
Belt tension - when you poke the belt, it should have a little give, but not be loose. See if it sags. And don't tighten it too much!
RE: Y-Shift 68mm from Bottom (could this be a toothed belt skip?)
Hi,
Many thanks for answer!
It is in fact both: a X-Axis shift (some little step to the left) and an Y-axis shift (some little distance to the front)
In both directions it _overshoots_ the position of the layers below (so maybee this could not be a collision then?)
All the layers are looking fine above this line. even the minute vertical patterns (somewhere else associated with step motor issues?)
are exactly continued in the print above line. perfect print - only looks as if the positional control lost one or more steps in X-left and Y-front direction and therefore adds them to every layer above.
X-axis moves smoothly. and the belts can be plucked like a soft guitar string...
I will try again with PLA material . I just started to use PETG and observed a little bit more issues with PETG(some very fine strings) and sometimes a droplike buildup (I think in the corners). Maybee that was the source of the issue (again little collision and the control SW
then added an offset). I will optimize the camera position (currently looking to far from side at heigh of build plate, so not looking on top
layer)
Greetings,
ckranich
RE: Y-Shift 68mm from Bottom (could this be a toothed belt skip?)
Software doesn't usually cause them. But any "crash" or motor stall introduces a permanent offset in the print: aka, a shift. Most often it is a friction problem where an axis bearing snags on itself for lack of lubrication. Sometimes because a bearing retainer is too tight. Since it happens above a certain height on your printer, look for drooping cables snagging the EINSY case, filament snagging the frame or spool holder, etc. It can also be a misalignment of an axis where the higher the axis is the more friction is introduced.
Do a self test and review the belt tension numbers. They mean nothing for belt tension, but are useful to find high friction. Both numbers should be close to equal, and the higher the better. 240 is silly high friction.