Layer shift and base coming loose
Earlier this evening I started printing a wedge for my video doorbell, 112x62mm. Material is silver PLA from Prusa Research. The printer is new, but printed a gimbal lock successfully yesterday. The gimbal lock was from thingiverse, sliced with Slic3r Prusa edition.
When I created my own design with tinkercad and ran it through Slic3r the print started out fine at first, but then, a dozen or so layers in, shifted about 5mm back. Here is an image:
The holes in the front should be on top of each other. The picture seems a bit warped, but in reality the frame is perfectly square and the lines are straight, only shifted 5mm up a few layers in. It was still stuck well to the bed when I noticed and aborted the print. What i noticed is that the print is rather untidy in the left rear corner.
... and also the right front:
Here is the back where it adhered to the bed. The untidy looking parts are the underside of the shifted layers.
Orientation was the front with the two (four) holes was parallel to the frame, shift was backwards (toward printer motor) on the Y axis. Belt is neither loose nor too taut. I made sure to have the screw on the Y axis motor on the flat part.
Later i tried to print the frog, which came loose after a number of layers. At first it seemed to print perfectly, but then it came off the pad and I had to abort. Here is a picture:
I am still getting my bearings, that the gimbal lock printed right yesterday was apparently beginner's luck.
Any advice on what happened and how i can prevent it would be highly appreciated. Guesses welcome.
Thanks!
C
Re: Layer shift and base coming loose
the underside of the oblong part suggests that your Live Z is a touch high still, try making the value a little larger negative number.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Layer shift and base coming loose
Thanks, I'll try that tonight and report back.
Any advice about the untidy sections?
Re: Layer shift and base coming loose
I tried to print the wedge again with more -Z. Indeed the outer surface looks much better and it sticks well, but for some reason on the left side and around the bore holes too much material is applied, so the sections are becoming thicker than the rest and the print head hits them. I think that's the reason for the Y shift in the other print. The problem is not everywhere, it is most pronounced around the right front hole and almost the whole left side. Not sure whether the wall there is too thin so the slicer isnt sure whether the section should be hollow or not.
New (right) vs old:
Note the bunched up material on the right:
And the shift around the left hole (~4mm):
New bottom layer from below: Looks much better.
So the question is, is this a design defect on my part? A slicer problem? Some printer setting?
Thanks
C
Re: Layer shift and base coming loose
First thing that comes to my mind is a mechanical problem with Y. When the shift happens, do you here the stepper skipping steps?
Check that the belt holder under the Y carriage/heatbed is not loose.
Check that the idler can turn freely
Check the belt tension
Check that the pulley is correctly and firmly mounted (one screw on flat of the motor shaft)
Check that the Y motor is in corrected position and not loose - check here from all sides if the motor has full contact to the the motor holders surface
Check there is nothing holding the heatbed when moving (cables, zip ties ...)
Re: Layer shift and base coming loose
What I heard on the last attempt was that it sounded like the extruder was scraping on the parts where too much material was deposited. It did not sound like the stepper was skipping steps. The scraping was not hard enough to loosen the model from the heat plate. I'll check all the pieces you mentioned.
What stumps me, is that there appears to be one shift, then its printing several layers on that new position. If the stepper was skipping steps, the pulley was loose or the heat bed was stuck somehow, there should be either random or continuous shifts, not a single shift at a specific position. The second print was resliced, by the way, albeit also with Slic3r Prusa edition.
Re: Layer shift and base coming loose
What stumps me, is that there appears to be one shift, then its printing several layers on that new position. If the stepper was skipping steps, the pulley was loose or the heat bed was stuck somehow, there should be either random or continuous shifts, not a single shift at a specific position. The second print was resliced, by the way, albeit also with Slic3r Prusa edition.
It could be that the gcode at this time makes some movement that triggers the slightly loose part to come out of place.
You could cross check your gcode with gcode viewers like http://gcode.ws But I guess it is not the problem.