Y-Axis Shift - constant problem..

Hi all,

I am running the latest version of Repetier firmware on my Gen 6 board and am using Repetier host + Slic3r.
The print quality is now very good but I am having constant Y shift problems, even at very low speeds. (35mm/s average)

It seems to occur randomly and for no reason.
Mechanically I do not think there is an issue, I am using LM8UU bearings, GT2 belts and metal pulleys and my bed slides easily.
The motor current seems correct, the motor does not get hot nor struggle to move.

I have been playing with Jerk and Acceleration settings, they are currently;

#define MAX_ACCELERATION_UNITS_PER_SQ_SECOND {2000,2000,100}
#define MAX_TRAVEL_ACCELERATION_UNITS_PER_SQ_SECOND {2000,2000,100}

and;

#define MAX_JERK 30.0
#define MAX_ZJERK 0.3

I have also set below as my Y-stop cable runs alongside the stepper wires, I have heard this can cause cross talk.
#define ALWAYS_CHECK_ENDSTOPS false

Can anyone assist? I'm getting very annoyed as I cannot run and decent size job without it being ruined.

Cheers,
Ash

... check for loose pulleys, sufficient torque (motor current) or mechanical problems like friction or such ...

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Viktor
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Call for the project "garbage-free seas" - [reprap.org]

Check the wiring to the endstops so that they isnt to close to the motor wires, the "noise" from the motor wires can give a false signal from the endstop.

Check so that your speed is ok with the motor voltage.
Every motor generates a reversed voltage that at a specific speed exceeds its feeding voltage. At that time you do not get any torc anymore and skip steps.

[3dlabtek.weebly.com]?

This really helps.
Limit the vibration frequency to 9000HZ;