Consistent 1.5mm Y Axis Layer Shift
Hi Everyone,
I'm having a major problem with Y axis layer shifts on my Mk3 with MMU2. Ever since I've upgraded to MMU2 I've had occasional problems with Y axis layer shifting. It almost always happens on longer and bigger prints. This happens on firmware 3.4.1 and 3.5.1 using MMU2 in single filament mode.
The layer shifting is very specific. It is a 1.5mm shift on the Y axis for a number of layers then it will revert to normal then shift again later. It is random where it will shift, but the shifts are always 1.5mm.
Initially I thought this was an issue with the stepper but it can't be because it is always 1.5mm and it returns to the nominal position after a few layers. If the stepper was skipping steps then it would never be able to return to it's nominal Y position.
Please can someone help?
Here are some pics -you can see the couple of layers where it reverts back to nominal, then it shifts again by exactly the same amount as before:
Re: Consistent 1.5mm Y Axis Layer Shift
Check for loose belt/ tighten it. And deactivate crash detection.
This are the two things I would do first.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Consistent 1.5mm Y Axis Layer Shift
I will test deactivated crash detection but it can't be a belt issue. Because the layers have a precise offset THEN return to their nominal position it cannot be anything to do with slippage, lost steps etc -otherwise it would never return to the nominal and would progressively get worse as the print progresses.
Re: Consistent 1.5mm Y Axis Layer Shift
I will test deactivated crash detection but it can't be a belt issue. Because the layers have a precise offset THEN return to their nominal position it cannot be anything to do with slippage, lost steps etc -otherwise it would never return to the nominal and would progressively get worse as the print progresses.
It depends on the gcode. Usually you have a counter movement at some point. For example quick acceleration in +Y and couple layers later quick acceleration in -Y direction. Because of the symmetrical object it might get back to the origin.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Consistent 1.5mm Y Axis Layer Shift
I'm thinking loose motor pulley grub screws
Re: Consistent 1.5mm Y Axis Layer Shift
I'm thinking loose motor pulley grub screws
Agreed.
Re: Consistent 1.5mm Y Axis Layer Shift
I'm thinking loose motor pulley grub screws
my money's on this
I have a Prusa,therefore I research.
Re: Consistent 1.5mm Y Axis Layer Shift
Nikolai, you're right of course. Skipping steps in one direction will produce the offset, then skipping steps again whilst the bed moves in the other direction will correct the offset.
However it certainly isn't a loose motor pulley. I've held the motor shaft tight with pliers and confirmed that the bed cannot budge at all.
So it appears to be that something is causing the stepper to skip steps.
I'm thinking a poor wiring connection is the most likely culprit. The motor itself should be pretty robust I guess -anyone heard of the motors failing in this way?
Also what about the main controller? Can they fail and cause this?
Re: Consistent 1.5mm Y Axis Layer Shift
im around stepper motors often. i might see the controller doing it before the motor itself, unless it's binding. but i b think you would feel that.
have you turned off crash detection?
I have a Prusa,therefore I research.
Re: Consistent 1.5mm Y Axis Layer Shift
I'm confused.
So I turned off Crash Detection and also fiddled with the stepper connections back at the Einsy to make sure they were properly seated.
One or other of those things worked. I've now done two perfect prints.
So how is it about crash detection that could have caused the offsets?
I might turn crash detection back on to see if that causes the problems to reoccur.
Re: Consistent 1.5mm Y Axis Layer Shift
just a possibility Crash Detection was/is going nuts. glad its working.
I have a Prusa,therefore I research.
Re: Consistent 1.5mm Y Axis Layer Shift
I'm confused.
So I turned off Crash Detection and also fiddled with the stepper connections back at the Einsy to make sure they were properly seated.
One or other of those things worked. I've now done two perfect prints.
So how is it about crash detection that could have caused the offsets?
I might turn crash detection back on to see if that causes the problems to reoccur.
Crash detection creates way more problems than it solves. Permanently off on both my printers and I do not miss it.