Shifted / Offset layers in print

[ralphzoontjens]

Hi everyone,

I am printing in flexPLA and at some points the 3D printer creates shifts in the layers, only in the X-direction.
See the pic attached for an example.

There can be many causes:
http://reprap.org/wiki/Shifted_layers

The belt tensions are exactly right and the motors work fine.
I suspect a backlash in one of the C-clamps causing at some point too much friction.
Or can it be something simple like the arms needing oil?

Has anyone else had the same problem?

[uncle_bob]

Hi

Yes, I have seen exactly the same issue.

Since I don't know what kind of printer you are using, it is tough to know if my slipping parts are the same as yours. Set screws on D shafts can do that.

Bob

[richardphat]

Have you repeat the print and did it happen again?

Typical issue could be your nozzle slamming your print. Make sure nozzle is cleaned and doesnt have a huge junk of crap sticking on it.

[ralphzoontjens]

It happens in about 1 out of 10 prints that I do.
I reassembled the print arms and checked the electronics - one of the heatsinks on the motor stepper drivers is missing so I am suspecting that this motor is skipping steps causing the offsets. I will put on some thermal paste and see if it resolves the issue.

[uncle_bob]

Hi

If you have rate dependent thermal motor shutdown, the answer may be to drop the speed. If it's purely thermal, it should happen when the printer has been on for a while. In that case, you may have to much current headed into the motors. The little paste on heatsinks do very little for the drivers. You can get a little more benefit from a fan. Even there the benefit is less than you might think. The way the chips cool and the pc board layouts don't generally work very well together.

Bob

[richardphat]

Dont just put the heatsink, put also a fan or make sure it is running free. Sleeves bearing clogged up easily and needs to be cleaned frequently.

[ralphzoontjens]

Hi Bob, thank you - it happens when the printer has been on for a long while, and indeed the cooling paste doesn't help very much. So when I turn it off between prints to let it cool down it works as normal again. Thanks!

[uncle_bob]

Hi

Put a fan on it. Running the chips hot shortens their life.

Bob

[mrduongonline1]

Make sure nozzle is cleaned and doesnt have a huge junk of crap sticking on it. In that case, you may have to much current headed into the motors