New issue - now with video! Y axis skip...

It is a consistent skip that just appeared over night. I have re-seated the pulley, I have changed the tension on the y belt, nothing fixes it. The pulley looks to be in good shape but it is always at the same exact point so I'm thinking that is where the issue lies.

This bump -> skip happens both when printing and when moving the bed by hand.

Is it time to buy another motor? Is it time to get another pulley? Help!

So many problems lately and I'm REALLY behind on what I want printed. This is driving me crazy.

https://www.youtube.com/watch?v=dkUjTnzHkCI

Is there something binding on the idlers or something getting in the way in the extrusion? Does it do it without the belt connected?

Nothing binding - I completely took it apart, cleaned it and put it back together to make sure it wasn't slipping. It doesn't do it with the belt off. I think the motor is fine, I believe somehow the pulley has a bum tooth? Has this ever happened to anyone?

If it doesn't do it with the belt attached then carefully examine the pulley and belt, and replace whichever one has the defect.

I have extra belts - I'll be testing that out tonight. Any idea on a local source for the pulley? Any B&M stores that might carry one?

As the pulley rotates there seems to be a lump or bump that you can see rotating around the pulley. There's likely something stuck to either the belt or the pulley... I'd start by fixing that.

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Originally Posted by printbus

The video is limited since it can't go full screen, but as the pulley rotates there seems to be a lump or bump that you can see rotating around the pulley. There's likely something stuck to either the belt or the pulley... I'd start by fixing that.

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I took it completely apart and cleaned them both but found nothing. The motor doesn't wobble without the belt and I can't "see" any defect when they are apart, just when they are working together. It's also at the same point in rotation. So I was with you initially that something got lodged in between the two but I haven't found crap! lol.

You can physically see a bump under the belt at the pulley when the skip happens. A video of the motor performing the same movements, from the same viewpoint, just without the belt in place would be interesting and potentially helpful.

Have you checked the set screw? One time I had a set screw that went bad somehow and would not grip onto the stepper motor. So I was getting weird Y axis artifacts.

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Originally Posted by BLKKROW

Have you checked the set screw? One time I had a set screw that went bad somehow and would not grip onto the stepper motor. So I was getting weird Y axis artifacts.

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That makes sense - under load the loose set screw could allow the pulley to slip across the flat, but without the belt in place and under no load, the pulley would stay in place.

So I took the y-axis motor out and took the pulley off of it multiple times - it didn't look bad but I found an aluminum GT2 20Teeth pulley that I replaced it with and it fixed the odd jitters. After looking much closer at the removed pulley it looks like there is a TINY fracture in it that changes the size of one of the valleys and it was just enough to cause issues. This was annoying.

Thank you all for your help.

Hi

The pulley appears to be a standard part at the Open Builds Parts Store. It's the same place the V-Slot comes from and the low head M5 screws.

When you tighten down the pulley, only use the set screw over the flat. Make sure it is dead square or you will get a "thump" and a slip each time the motion reverses. Once you are sure it's tight and square, go ahead and tighten the other set screw. Usually what happens is that both are fairly tight and eventually the "not on flat" one slips a bit. You then get an intermittent bump on the pulley.

Bob