Skipping Steps in only one direction, Help pls

Hi, everyone , first of all, thanks to all this community because I got a lot of help for building my prusa I3.
My problem is that i don't know why my prusa i3 has began to skip steps in only one direction (Y-) so the layers tend to move to the Y- as in the photos. My guess is that it's a mechanical problem because i carried it from my other house ; but I've checked almost anything: lubricate all the axis, slow the speed, loosen the Ycarriage belt, reload Marlin. And the weird thing is that it only skips in the Y- direction.

Here some pictures of the problem
[i.imgur.com]
[i.imgur.com]
[i.imgur.com]

Hoping for some ideas

Usually the endstop is triggering too soon, from looseness or noise.

Hi,

I agree with a mecanical issue.
Don't loose the belts. It must be tight, not overtight.

Check the bed can move easily in both directions.

This can be a belt running properly in a direction,
then rubing on a side when returning.
Are the puleys in line ? Is it a proper idler pulley ?

This can be a bearing problem too.
Some cheap LM8UU have squared balls into their ways
and do not run properly, and cause some loose steps.

This can be an under powered driver too.
Because of transport of for any electrical reason,
the amount of current to the driver changed.

++JM

Ok, thanks i will check the endstop an try to lubricate again the LM8UU and check the current from the drivers. By the way, yes they are in line. Thanks for the quickly answers I will try to check that as soon as possible

Ok, so no success so far, i checked the endstop and it's working ok. Checked the current from the Y carriage and it's about 250-240mA but i set it a bit higher because the carriage and the heatbed are made of aluminum so I thought a higher current would be necessary. I lubrecated the Y axis. This time i recorded a video so you can see it better : [youtu.be] .
And also took some photos of the final print:
[imgur.com]
[imgur.com]
[imgur.com]

Waiting for some ideas because I don't know what it can be... ;(

Video is private.

As for the endstops, yes they can work when you test them, but the trouble is when they also trigger before they are supposed to.

This can come from two issues:
1: Check if your corresponding axis has some resistance (mechanical)
2: Check if your stepper driver is calibrated correctly, either the stepper motor does not get enough current to drive the axis or the stepper driver overheats.

do you cool your drivers?

Ok the video is already public. Ok then I will buy a new endstop. I think there is no mechanical resistance because I can move the bed with one finger and no problem. The current in the driver i think is correct because is aboout 240-250 mA because of both carriage and bed are made of aluminum. Yes I cool all the electronics with 2 fans (G3D pack). Hope the video now can make things easier.

My drivers are sdjusted to approx .65 volts on both x and y. I really had to tighten the y axis belt. I mean tight tight.

Check that the Y motor pulley is tight and not slipping.

Make sure Y endstop wires are not near anything powerful. Maybe do the gcode for endstop reporting, and jog the Y back and forth, so it will tell you if the switch triggers. And of course put the new switch in when you get it.

Do a series of tests of a cube, with Y-speed going low to high, and another series with Y motor stepper driver going from low to high.

I had the same problem and it was due to wrong settings in Marlin, the software to command the printer.

First try to operate the minimum setting switch. If you press the minimum setting switch (zero-position switch) and hold it, if you then can send the printer on both directions, it is surely the settings in Marlin.

If you open Marlin with the program: Arduino, you will find a third tab-sheet: "Configuration H"

Somewhere in the middle of this sheet you can find : // Mechanical endstop with COM to ground and NC to Signal uses "false" here (most common setup).

What follows below I changed to:
const bool X_MIN_ENDSTOP_INVERTING = false; // set to true to invert the logic of the endstop.
const bool Y_MIN_ENDSTOP_INVERTING = false; // set to true to invert the logic of the endstop.
const bool Z_MIN_ENDSTOP_INVERTING = false; // set to true to invert the logic of the endstop.
const bool X_MAX_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.
const bool Y_MAX_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.
const bool Z_MAX_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.
const bool Z_PROBE_ENDSTOP_INVERTING = false; // set to true to invert the logic of the endstop.

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hdie support

Ok this week I'm not actually at home so next week i will try everything you're saying. Thanks for all the help