Y axis Offset error every z layering ?

em9al

HI.
I am new to 3D printing, but have a friend helping me a lot.
Everthing seems to work exept one mysterious thing...
Every new Z layering the Y axis in munus direction is displaced buy 1 to 2 mm ?
I use this Cube for test:  XYZ 20mm Calibration Cube
https://cdn.thingiverse.com/renders/55/57/31/81/53/34dcf6594a055b63bccf0ce58f21f1d3_preview_card.jpg
But the result is like this:
https://photos.app.goo.gl/ZUKO8TC9pn9lijxG2


Hardware or software error ?

Best Åke.

Repetier

Hardware problem. Your y endstop suffers from crosstalk so y moves are sometimes stopped early thinking it hit an endstop.
Solution 1: Twist Y endstop cable and motor/heater cables running in parallel having contact to it.
Solution 2: Set ALWAYS_CHECK_ENDSTOPS 0 in configuration.h (repetier-firmware) to disable testing while printing.

1 would be best but both should help.

em9al

Many thanks for your answer .
I have Done the Always check endstops 0.
No different .
But what do you mean by Cosstalk and twist the cabels?
The problem is within the slice the y is Always right.
But when next layer is started IT move in Y -

Repetier

If you have 2 parallel wires and one gets power for a short period it builds a magnetic field introducing some energy in parallel lines. Just like motors work. If board measures endstop just at that moment it could be over 2.5 or so V and handle it as triggered. This is a problem also for networks with high frequencies, so all network cables are twisted and shielded to prevent just this type of crosstalk plus some other tricks. You can do the same trick here so motor and heater cables witch also have high current hence bigger fields have less effect on it.

Other reasons are stalling motors so they miss some parts resulting in same pattern. This can be because oyu hit some hard plastic pointing upside (curling) or just exceed acceleration/speed so force is not high enough to catch up some small interferences. If you watch a print closely, you normally can hear loosing steps.

em9al

Thanks for a very good answer.
I will test to twist the endstop cables and seperate the motor cables and the endstop cables.
Now they are running in the same v-slot and some back and force just becurse it is long cables.
I will also short this cables.

papagino

Hi em9al, I thing your problem is with not enough current going to your y axis stepper motor and it is skipping steps because of it. Not sure what control board you have, but try to increase current for the y axis stepper motor to see it the problem goes away.

Cheers
Dan