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Very strange layer shifting  

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Pieter
(@pieter-4)
Active Member
Very strange layer shifting

Hi everybody,

I've been able to print everything on my MK3, things came out excellent. But then all of a sudden, I started to get layer shifting problems. So I started checking out the forums and everything. My belts were loose, but not anymore. My live z-adjust was a bit off, but not any more. I used Octoprint, but got same results with printing directly from the SD card. I tried with / without z-hop (stringing with z-hop on, even on 0.2, because I print miniatures), hotter or colder temperature for the filament, everything in the guidebook (pulleys are secured, idler pulleys can move freely). I've switched the sensors off and on. Still, I get layer shifting in the Y-axis. Now I'm trying to print with a raft to see if I can get a decent print...

So now I'm lost... Any other tips are more than welcome.

Publié : 21/11/2018 10:08 pm
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(@)
Illustrious Member
Re: Very strange layer shifting

I can't tell from the images what is the part, a base or stand, etc.

If that slat-wall looking piece is printed along with the knobly looking things, its' worth noting it doesn't have any weird problems inside those grooves.

Try to get a clear image that illustrates exactly what you see as the problem.

Or print this and post a photo:
https://www.thingiverse.com/thing:2656594

Publié : 21/11/2018 10:56 pm
Pieter
(@pieter-4)
Active Member
Topic starter answered:
Re: Very strange layer shifting

Sorry, I can imagine that you can't tell what it is. I printed the test and again layer shifting. This time on the X-axis though...
..

Publié : 22/11/2018 8:00 pm
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(@)
Illustrious Member
Re: Very strange layer shifting

Especially with images upside down. lol.

I've never experienced layer shifts like you are having, so can't give any definitive cause. All I can do is give plausible reasons you can check for.

It looks like both X and Y axis are shifting. Correct me if that's wrong.

A power supply problem may explain motor torque issues causing missed steps. Switching to Stealth may be a test of this since Stealth uses a slightly different stepper algorithm.

A volt meter reading of the 12vMOT rail may also be good to know.- probe between ground and the test points on the fuse.

Sticky bearings? Stiction can cause excess drag force in places. Caused by wear, and deterioration of bearing seal materials. Power off, and roll the X and Y Axis back and forth through their entire range, if you feel any "tight" or "rough" spots, you may have an issue there.

A broken tooth on the drive belts or a filled tooth on the drive gear. A good inspection of belts and drive gears can point these out. But both axis failing at once makes this unlikely.

Failing memory card - but you've done prints off both Octo and SD, so also low chance.

Broken stepper motor cable. Again, low chance both axis fail at the same time. Back to power supply issues. Ensure the 12v motor fuse is good - replacing it is the best way to test a fuse.

Try these and report back ... good luck.

Publié : 22/11/2018 8:49 pm
Pieter
(@pieter-4)
Active Member
Topic starter answered:
Re: Very strange layer shifting

Yes, I don't know why the forum posts the images upside down... Ah well.

Now trying stealth mode to see if it makes a difference and ordering some super lube for the smooth rods. Hope it helps. Thanks for all the tips!

Publié : 22/11/2018 9:01 pm
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(@)
Illustrious Member
Re: Very strange layer shifting

Belts being too tight can make the travel feel sticky, too. Especially X-Axis, where a tight belt can bend the rods in the middle. Not so much on Y-Axis. I also question whether or not grease on the rods actually helps. The bearings have grease seals to keep grease inside the bearings. They also keep grease out. A light oil - one drop each side of the bearings - keeps the seals fresh.

Publié : 22/11/2018 10:15 pm
Pieter
(@pieter-4)
Active Member
Topic starter answered:
Re: Very strange layer shifting

I got it working properly again! Some grease, but also tweaking the x- and y-axis some more helped. It's printing reliably again. Thanks for all the tips, learning a lot.

Publié : 24/11/2018 3:42 pm
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