Frustrating corexy skipping

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jweston
Posts: 3
Joined: Tue Apr 09, 2019 10:10 am

Frustrating corexy skipping

Post by jweston » Tue Apr 09, 2019 11:46 am

I've been using my Promega since last August. I am quite familiar with belt tightening.

About a week and a half ago, my Promega began severe skipping, primarily in the x-axis, but it also affects the y-axis to a lesser extent. This began between prints although only a few minutes between them.

The nature of the skipping is that it's worst when it's closest to the home position (x max, y max). It even skips a little as it finishes homing. It skips a little if I move it down y but less as it gets away from home as long as it's only moving in the y-axis. It skips badly as it moves either way along the x-axis. Giving the carriage a push with my hand while moving it in the x-axis helps but not always enough to prevent skipping. When the printer is off, the carriage is extremely stiff to move along the x-axis, much more so than the y-axis. It does not become stuck in any particular place, though.

Both lower and upper belts appear to skip, depending on which direction the carriage is attempting to move. In fact, I can see that the pulleys aren't even turning much when it skips.

I have tightened, even shortened, the corexy belts to ensure get good tension and evenness. The belts are running properly through all of the bearings. I've also tried tightening the set screws in the pulleys to no avail.

Here are some videos demonstrating the behavior:
lower belt pulley during x-y home: https://drive.google.com/open?id=1XZ67G ... 1LbUC24z97
upper belt pulley during x-y home: https://drive.google.com/open?id=1NM1lp ... 2dgmgLbImc
lower belt pulley moving in x-axis: https://drive.google.com/open?id=1VIr34 ... o5ncXQr-NG
upper belt pulley moving in x-axis: https://drive.google.com/open?id=1zMOEq ... UUydAxbaPW

M3D's support has only been sending me to the same pages regarding tightening the corexy belts which of course was my first move.

Any ideas?

TheBum
Posts: 44
Joined: Tue Sep 11, 2018 4:41 pm

Re: Frustrating corexy skipping

Post by TheBum » Tue Apr 09, 2019 3:31 pm

Make sure the cable chain isn't snagging on the aluminum of the case. I had layer shifts until I constrained how much the first link in the chain (the one next to the right motor) can rotate back (I ran twist ties between the link and holes on the frame). That keeps the chain off the frame over the whole range of x-y movement.

jweston
Posts: 3
Joined: Tue Apr 09, 2019 10:10 am

Re: Frustrating corexy skipping

Post by jweston » Tue Apr 09, 2019 6:47 pm

Thanks for the thought but I don't think that's it. There is approximately 1cm of clearance above and below the cable chain which stays level.

Here's the chain: [url]]

TheBum
Posts: 44
Joined: Tue Sep 11, 2018 4:41 pm

Re: Frustrating corexy skipping

Post by TheBum » Wed Apr 10, 2019 12:17 pm

Make sure the belts aren't too tight. They can bind up the bearings, which definitely could cause skipping.

jweston
Posts: 3
Joined: Tue Apr 09, 2019 10:10 am

Re: Frustrating corexy skipping

Post by jweston » Wed Apr 10, 2019 7:51 pm

The belts were way too tight. Thank you so much!

Let it be said that belt tightening is not the cure to all skipping.

TheBum
Posts: 44
Joined: Tue Sep 11, 2018 4:41 pm

Re: Frustrating corexy skipping

Post by TheBum » Thu Apr 11, 2019 11:12 am

Glad at least one of my ideas stuck. I was about out of them.

patel
Posts: 2
Joined: Mon Aug 05, 2019 2:22 pm

Re: Frustrating corexy skipping

Post by patel » Mon Aug 05, 2019 2:29 pm



did not stop x axis why the limit switch corner

TheBum
Posts: 44
Joined: Tue Sep 11, 2018 4:41 pm

Re: Frustrating corexy skipping

Post by TheBum » Mon Aug 05, 2019 3:14 pm

Not sure I understand the question. The Maestro has to home Y first because, otherwise, the head would likely never hit the X limit switch when ithe Maestro tried to home X. So, if you home only X through the DWC, the Maestro will automatically home Y too.

patel
Posts: 2
Joined: Mon Aug 05, 2019 2:22 pm

Re: Frustrating corexy skipping

Post by patel » Wed Aug 07, 2019 3:34 pm

i fix this issue by using S1 drive 2 but i have other prdoble IR Probe did not work LED are solid state did not turn off

TheBum
Posts: 44
Joined: Tue Sep 11, 2018 4:41 pm

Re: Frustrating corexy skipping

Post by TheBum » Thu Aug 08, 2019 11:12 am

Are you using a glass sheet, glass fiber sheet, or a sticker on the bed itself? The IR probe is pretty worthless for glass and probably worthless for the glass fiber. It might be OK for a matte black sticker on the bed though.

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