My Steppers are skipping or the pulleys have come lose right

[teoman]

I have been having some trouble printing lately.

I have more or less diagnosed my problem to be my pulleys not holding tight anymore. However i would also like a second opinion.

The print starts off fine. But after the first few layers it shifts and it also seems like the hotend is trying to dig in to the print towards one corner. My Y tower motor seems to be getting a little bit hot aswell. It did not do this before.


I have recently fiddled with the 24V power supply, tightened my carriages (they were very lose), tightened my belts (trying to solve this problem).


Anyone has any opinions before i tear in to the machine to get at the pulleys?

[teoman]

Ok, I need help.

What I have checked:

1) I have examined the belts, there are no flat spots and all the teeth seem to be ok.
2) I checked the pulleys, I had marked them with nail polish and they had not shifted at all, while peeking at the pulley with a flashlight, i quickly moved the carriage up and down and they do not seem to be rotating on the motor shaft.
3) I have extensively fondled the carriages individually up and down and there does not seem to be a rough spot or anything bizzarre. If i move the carriages down very fast then i do get the belt jumping. But there is no way the carriages move so fast or with so much force.
4) I have extensively fondled the end effector and there does not seem to be a travesty.
5) Checked temperature of the motors, they do not seem to be overly hot.
6) Power supplies seem to be functioning normally and the printer keeps its temperatures perfectly.
7) When the big and wide print failed I tried different prints.
8) Tried slowing down to %60 percent speed.
9) Lowering the extrusion multiplier to %90.

While it is printing, the first few layers are as good as before, but then something happens and suddenly the nozzle moves way down, it continues printing and smashes through the part. I tried but could not yet catch the exact moment it happens, my eyes still burn from the LED light attached.

PS: My heatsinks had fallen off, so i will try again now. I shall also try to bundle up the wires on the hotend just in case.

[teoman]

Still no joy.

[KAS]

on number two, did you have the motors locked with power or able to free spin? Reason I asked is because you might have enough friction in the shaft of the pulley to turn the shaft/stepper even without the set screw fully engaged when the steppers have no power. It's also possible that it's just loose enough for the set screw to catch the edges of the flat spot on direction changes and not fully spin; just not sure if that would relate to the issues you're having.

Also, I was able to remove the steppers completely without much trouble by getting creative with screw driver angles through the various holes in the mounts. I had to adjust the gear a bit because of the damper install. On a v2 if that matters.

[teoman]

Thanks. But they appear not to be spinning.

The problem is also progressive.

The shifting is away from the Y tower.

Later it shifted much more and hit the part and i had to stop it.

[Earthbound]

Looking at #3. Belt on Y tower slightly loose?

[rpress]

Another member just had this problem too and it was fixed with:

Code: Select all

#define ALWAYS_CHECK_ENDSTOPS 0

in Configuration.h. Worth a try.

[KAS]

I guess you could switch the stepper connection around on the controller to see if the part starts moving that predictable way.

At least that would tell you for sure if that stepper is trashed.

[teoman]

@ Earthbound, I have now tightened the Y belt.
@ Kas, i have switched the endstop and motor connections on the rambo board. This will cause a slight problem with my endstop calibration (because i do not use the screws but the EEPROM offset settings instead. But they are close enough so it should be able to print.

@ rpress, I will try that a bit further on as i have not been fiddling the wires of the printer at all. But if this set of changes fails i will try it next.

Well, i have started the print. We shall see what comes out this time.

[teoman]

So far so good.

@KAS, for some reason when i switched the endstops and the motor connectors X and Y towers moved in opposite directions (relative to their respective normal direction), which puzzles me as I had not changed the firmware in any way during the build. So i switched them back to their original positions. Or thinking of it, i think they were originally inverted in the software because the motors are positioned symmetrically.
@rpess, the problem may have been related to what you suggested. While fiddling with the rambo i did move the endstop and motor wires as far away from each other as possible.

Wife is now monitoring the print. I will report once i get back home.

[teoman]

UPDATE:

Seems the problem is gone. Thanks to all involved.

I did tighten the X Axis belt. And moved the wires. I do believe it was the endstop wires being too close to the motor wires.

Will try a few more prints and report back.

[teoman]

Well i had success with a very small print a couple of times but besides that it just keeps shifting.

Now i have a new symptom. Ater the first few layers it freezes.

The nozzle just stops where it is. The printer is still functionnal. It keeps temperatures regulated. The LCD works. I can home the printer.

I was thining it may be temerature related, but i doubt it is. It usually fails within 15-20 minutes. With the enclosure door open. It has printed for hours before. The fan cooling the rambo is a noctua fan.

I removed the usb cable (i print exclusively from the SD card) and I have tried a different sd card with the same results. I can only print 3 to 15 layers.

Any ideas?

[teoman]

I had the LCD panel out and I think cables were picking up noise (As some one recommended on another thread). The part that is printing now has gotten further than any before.

[rpress]

Another member just had this problem too and it was fixed with:

Code: Select all

#define ALWAYS_CHECK_ENDSTOPS 0

in Configuration.h. Worth a try.

Hebe you done the above? This would rule out noise from the end stops.

[teoman]

Code: Select all

// You can disable endstop checking for print moves. This is needed, if you get sometimes
// false signals from your endstops. If your endstops don't give false signals, you
// can set it on for safety.
#define ALWAYS_CHECK_ENDSTOPS false

This is what i have there.


I just noticed that one of my motors is slightly lose. It wobles a litle bit. But i doubt that that is the problem. That would create ripples and not a definite shift.


I still have the shift. Not sure how to get rid of it. I did get a couple of good parts printed. (small matchbox sized parts).

[teoman]

I have fiddled with it a little bit and recently it seems that it is not shifting anymore but it is just freezing. I have not idea what the problem is.

When it freezes the lcd is still operational.

I do have a new symptom, somethimes when i hit home, all the towers start going up, the X carriage stops half way untill the other carriages reach the top and then the X tower moves up very very slowly. It seems like a problem with the end stop signal from the X tower.

I have moved the ssr and the power cable a bit further away from the printer and i am trying again now.