Large layer shifting problems

[cstoelzel]

The problem that is plaguing me from the beginning is LARGE layer shifts. Like 1-3 cm layer shifts after a 1 cm or so up in Z. I've lucked out and gotten some really nice big prints of it... but then... I go and deal with a relatively simple but large print and have like 6 failures in a row.. .each at least a couple hours into the print. things like calibration cubs and benchys which are taller than I might see the first shift, seem print fine.

I thought I had solved the shifting in the X direction as I hadn't seen it for a month, until my print two nights ago... anyway, things I have tried

I slice in cura, and as I said, I have gotten some successful prints off the pro A, just not a success rate that seems right.

1 - checked the smooth rods on each axis, both by removing and checking, and by swapping out from my old printer (An old Mendel I built 4 years back or so)- returned the geeetech ones to the setup.

2 - belt tightness, a million different ways, swapped the y axis bet holder to another full aluminum that doesn't need whole punch as I was afraid it might be slipping.

3 - replaced the bearings. Greased the bearings, noting that when the belts are disconnected, both axis slide smoothly I didn't expect an improvement, but for completeness tried it.

4 - rebuilt the idlers. replacing the M4 screw with an M3, and slightly opening them up a bit.

5 - opened up the control box, and checked the stepper voltages.... running prints with the steppers at 0.8 (default), at 1.0 and at 1.2. get the slippage on all of them. .. So I also tried taking the stepstick from the 2nd extruder slot, and the connector cable running from board to breakout box on the back and moved that over to the Y axis slots. and saw slipping along the Y again (assuming the X motor stopped, and Y moved at that moment, I then swapped out the X stick and cable. still slipped.

6 - added heat sinks to the stepsticks, with the tiniest drop of thermal paste.

7 - swapped out the motor cables for new ones from the breakout box on the printer to the motors for X and Y. still slippage.


What I will try shortly,
1 - again update the Marlin
2 - replace the ribbon cable maybe?





... and pretty much anything you kind folks might think I missed many thanks.

[_kaktus_]

Hello.


You approached the topic professionally.
You described your problem and the steps you have already taken to solve it.

However, in spite of your efforts (you tried all the important steps) the problem continues to plague you.

Therefore, I would like to tell you how I solved it in my case, and draw your attention to some fact.

I had this problem when the printer was new.
In retrospect, I can say that he partly gave way alone.
As the printer worked for many hours. So I think that the new mechanical components had to adapt/reach to each other.
But that's not all.
To help solve the problem, I slowed down the printer. I lubricated all linear guides with professional oil from large CNC machines (for slow running guides).

I also adjusted the Vref voltage in the stepstick module to increase the current supplied to the stepper motor.
Finally, I replaced all linear guides, because the original ones worn out very quickly. They were really of poor quality.

In my opinion, this problem arises when the printer has to perform very dynamic and fast movements. The heated bed has its own weight and a dynamic change of direction can cause the engine steps to be lost. The resulting force is simply greater than the engine power.
Therefore, it is very important that the mechanical components are almost perfectly matched.

Power loss can also be caused by heating of the stepstick chip.
This system has various protections which, when activated, may lead to a reduction of stepper motor power.

Share your opinion on what was helpful to you when you did the tests.
I greet you cordially.