Y-axis skipping?  

Re: Y-axis skipping?

1. is the screw of the pulley tight?
2. is the beltmount under the table fix?

Re: Y-axis skipping?

1. is the screw of the pulley tight?
2. is the beltmount under the table fix?

1.yes
2.yes

Re: Y-axis skipping?

Hey everyone, I have a little issue with my mk3's y axis. Every now and then the layer will be shifted by like .1mm or so, just enough to be noticeable and ruin an artistic print. I've checked the belt and did some manual pushing and pulling and had no slipping at all. Do I need to replace my y axis motor? and if this is the case, can someone point me to one that isn't from the official prusa store? I live in the US so shipping would cost way too much.

Can you post a photo? 0.1mm is a pretty small skip, it would be good to see what that looks like.

IMHO, the motor itself is unlikely to be the problem. Those steppers are pretty robust and reliable. I'd lean towards something mechanical first, like the pulley on the motor not being screwed on enough, or maybe a loose screw somewhere.

Re: Y-axis skipping?

I was randomly having this on my MK3. I'm running the last beta firmware. I haven't updated to the Final yet. I turned off crash detection and haven't had a layer shift since. Make note of what the Crash detection count is and do a print. Assuming you get a layer shift the counter will increase. If you already tested the belt and made sure it didn't slip when you pulled it etc. then that should be good. I also turned off the Filament sensor because it would randomly think I ran out while using eSun Black PETG.

I will wait for the next firmware and driver set before I upgrade.

Re: Y-axis skipping?

i had this happening intermittantly and what i found was that if the print bed thermistor wire was hanging just right it would catch occassionally so i readjusted to make sure it didn't get in the way again and havent had a layer shift since

Re: Y-axis skipping?

Hey everyone, I have a little issue with my mk3's y axis. Every now and then the layer will be shifted by like .1mm or so, just enough to be noticeable and ruin an artistic print. I've checked the belt and did some manual pushing and pulling and had no slipping at all. Do I need to replace my y axis motor? and if this is the case, can someone point me to one that isn't from the official prusa store? I live in the US so shipping would cost way too much.

Can you post a photo? 0.1mm is a pretty small skip, it would be good to see what that looks like.

IMHO, the motor itself is unlikely to be the problem. Those steppers are pretty robust and reliable. I'd lean towards something mechanical first, like the pulley on the motor not being screwed on enough, or maybe a loose screw somewhere.

When I said .1mm I was just guessing, I was trying to say that the layer skip was only just enough to be noticed, but yes I have two images below

https://drive.google.com/open?id=1bI32Uk6GiD3JhQN2RsqARz-3j9nP8vXE
https://drive.google.com/open?id=1yNZzya4SR2UlgxOnTUqD0bKTuhoZvCCB

I was randomly having this on my MK3. I'm running the last beta firmware. I haven't updated to the Final yet. I turned off crash detection and haven't had a layer shift since. Make note of what the Crash detection count is and do a print. Assuming you get a layer shift the counter will increase. If you already tested the belt and made sure it didn't slip when you pulled it etc. then that should be good. I also turned off the Filament sensor because it would randomly think I ran out while using eSun Black PETG.

I will wait for the next firmware and driver set before I upgrade.

I don't know when I started noticing this, but I do know that it happened before I upgraded to the most recent firmware as well, which was only like a few days ago. I have a print running right now so I can't look (atleast I don't think I can), so can you elaborate on how to turn off crash detection? Because although the posters above keep mentioning a loose screw or a wire hanging, I can assure everyone that this is not the case. The printer is assembled correctly. So I'd be very interested in turning off crash detection to see what happens. I also don't actually know what 'crash detection' means... the nozzle crashing somewhere? The bed crashing into the end?

Anyways, thank you everyone for the input so far.

EDIT: I went and checked the tune settings while the print was going, and found that the number of crashes on the y axis (4) matches the number of times this has happened, and it's only happened on the y axis. I also discovered that I could turn crash detection off mid-print, so I did. Maybe this will change things? Who knows, I guess I'll have to keep printing and see.

Re: Y-axis skipping?

I too had random layer shifts exactly like this after moving to 3.1.1 final, including one that ruined a 9 hour print. I turned off crash detection and have not had one since. I am convinced that false crash detects were actually causing the problem.

Re: Y-axis skipping?

on your pics it looks like one undetected layer shift (the lower one) and one detected one (where the rehoming brought the position back to normal). When you move your bed forwards and backwards by hand, does it always slide smooth or does it bind sometimes. Likely candidates for the latter would be the wire of the bed-thermistor (under the bed) or the wrapped bundle of heatbed wires (power and thermistor).

Re: Y-axis skipping?

on your pics it looks like one undetected layer shift (the lower one) and one detected one (where the rehoming brought the position back to normal). When you move your bed forwards and backwards by hand, does it always slide smooth or does it bind sometimes. Likely candidates for the latter would be the wire of the bed-thermistor (under the bed) or the wrapped bundle of heatbed wires (power and thermistor).

It's always smooth, like I mentioned before the printer was assembled correctly and nothing has come out of place.