Too much layer shifting

DjDemonD

It can be mechanical i.e. a print bed not properly secured so that it moves laterally my mini kossel does this as the bed mounts I made for FSR's are not clamps so the bed can shift it its not properly inserted, or electrical i.e. a motor skipping steps due to insufficient current, or being asked to move faster than it is able (i.e. insufficient current).

dvmourik

I am using the onboard drivers in this model. Nothing hardware related because changing the board will make it print flawless.
Sadly i was using pressure advance and this last print i removed it.

But i don't want to hijack this thread. So we keep it to the shifting of the topic owner.

Hugues

@Djdemon i monitored the print and there was not mechanical, nothing move like bed shifting. It's more like the board forget few step

deckingman

@cubexupgrade:

@Djdemon i monitored the print and there was not mechanical, nothing move like bed shifting. It's more like the board forget few step

But it only affects one motor, hence the 45 degree angle of shift (corexy). Loose wire? Bad motor? Can you swap the XY motors and see if the shift then happens in the other direction? Looking at all the stringing at the bottom of the model, are you sure the nozzle didn't catch on a lump of plastic which either shifted something mechanically, caused the pulley to slip, or caused the motor to skip a few steps?

@DC42, does interpolation affect motor torque? Just wondering if there is a mechanical resistance to movement, might a motor be more likely to skip steps with interpolation enabled.

dc42

Interpolation will have only a tiny effect on motor torque. Maximum torque is produced when the motor is nearly 2 full steps behind the commanded position. A few 1/256 steps either way isn't going to make much difference.

@cubexupgrade, are the two motors of the same type and definitely running at the same current? If you are using M584 to remap drivers, you should specify the mappings for all axes and extruders, and set the motor currents afterwards.

Hugues

@dc42 motors and current are the same. I haven't use motor mapping for this printer.

Since i deactivate interpolation i use pressure advance function without problem even with high accl/jerk. Maybe it's just hasard.
I do not push test because i've to print lot of stuff for works.

Phil Maddox

Hi all
Was this issue ever resolved ?? Im having similar problems ( 1,5 & 1.16)
Prusa i3 steel Cartesian . Works fine with a ramps 1.4 with TMC 2100's

Doesn't always happen.
Doesn't happen at the same height
When it occurs its X and Y at the same time but not by the same amount.
Checked all the usual suspects but as yet no real culprit to be found
All help / input appreciatted

Sniffle

scientifically(one test print at a time), try reducing or eliminating your pressure advance first, then lowering your accel and jerk settings to what would be a more "normal(i3)" level.

I eliminated my layer shifting by greatly reducing my accel and jerk settings and there has been mention of potential issues with to many steps being generated on circular moves from pressure advance that can cause steps to be lost, though i think this was also squashed or its impact reduced.

Phil Maddox

Thanks ill certainly try that
Whats wierd is in the 2 months or so that ive been using the Duet Wifi its worked fantastically well on large and small prints alike . Just this past week or so ive had problems.
I'm not 100% convinced it the Duet Wifi but with all the usual suspects checked and double checked, i'm at a bit of a loss as to whats going on.
The only thing that has actually changed that i know of is ive upgraded to Simplfy 3D 3.1.1 but i cant really see how that would create this issue.
Maybe i should try another slicer to be sure.

T3P3Tony

Sometimes layer shifting is caused by slipping pulleys at high speed acceleration.

cap

one thing i noticed sorry no tech guy here but are any of the motor wires crossing are touching as this coursed me problems

Phil Maddox

@T3P3Tony:

Sometimes layer shifting is caused by slipping pulleys at high speed acceleration.

Would seem odd that both X & Y slipped at the same point in time/ the print and only once per print
Already checked them and am 100% sure they are super tight.

Phil Maddox

@cap:

one thing i noticed sorry no tech guy here but are any of the motor wires crossing are touching as this coursed me problems

Im confident the wiring is not the issue

deckingman

Here are some more possible reasons for shifted layers http://reprap.org/wiki/Shifted_layers