Layer Shifting

[printerfan 5]

I own an ultimaker original with an official heated bed added.

I use Cura and have occasionally had issues with layer shifting in some of my prints. I am currently trying to print the Inmoov arm, but on one of the taller parts I have been experiencing layer shifting.

Yet this other piece for the arm, about an inch or so shorter, but similar in complexity came out fine:

I need help figuring out why this is occurring. Here are possible causes of layer shifting from what I have read:

1. Stepper motors overheating.

- For: Occurs in longer prints (>4 hours).

-Against: Printing open to air in cool basement (55-65 degrees F). Does not consistently occur with long prints.

2. Loose belts

-For: my ultimaker was purchased preowned (I'm not sure how many print hours it has)

-Against: belts feel tight (but I'm amateur and don't know what "tight vs somewhat loose" feels like).

3. Electronics (Low current or voltage drop)

-For: I've had cables become loose on the underside of the printer before and effect power to printer.

Also, my house occasionally has flickering in lights (Not something I notice daily, but have seen it happen.)

-Against: I printed same tall 11 hour piece twice, and layer shifting occurred within 2 mm of same layer height, yet printed 8 hour model that was inch shorter and no layer shifting. This could be possible if voltage drop occurred at same time during each day due to issue with house electronics and I likely started the second print of the 11 hour piece at the same time of day.

4. Jerk or Acceleration Setting are Non-ideal

-For: I was experiencing ringing in a few prints couples years ago and did change my Jerk and Acceleration settings per forum member recommendations.

I have heard occasionally my printer excessively vibrate/resonate during some prints and it sounds awful. This doesn't happen every print, but I hear it sometimes.

-Against: I have done a good number of prints since adjusting Jerk and Acceleration settings and most do not have layer shifting.

Also I printed Tom's resonance test piece. I didn't understand his instructions, so I set them as I thought it was telling me (1.0 shell thickness, 100% fill density, 'normal print speed' setting, default size of object)

https://www.youmagine.com/designs/resonance-test#activity

Printed one with a Raft, one without Raft

Results came out fine:

5. Nozzle impacting print as it reaches top of tall print

Unlikely, but I've heard of this happening to people.

[neotko 1,417]

You forgot the main one. Pulleys screws might not be as tight as they should. Check the 12 pulleys (motor pulleys included). If in doubt, mark pulley/shaft and print, as soon it slips check the painted marks to locate the slipping pulley.

[ultiarjan 1,221]

http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#shifted

Check if you have a loose pully. They really need to be super tight.

[printerfan 5]

Thanks for the replies guys, I will check the pulley screws today. In the mean time a different 11 hour print came off the bed this morning, it was of a different, but similar part of the Inmoov arm. This part is of the same height as the one that experienced the layer shifting, but this one came out pretty good. Only thing I changed was infill to 80% through basic settings, I was previously using the 'quick print normal setting', which I don't know the infill % on that, but it definitely is less than 80%.

Overall, new print came out good, only real issue is the over hang has a "chewed up" appearance.

I have a single extrusion fan with shroud, 50m/s print speed, 210C nozzle temp. Any advice for improving the overhang?

[printerfan 5]

I just realized the part with poor overhangs is luckily an anti-warping structure for printing in ABS (I used PLA, so next print I will remove it in Cura). However, still curious as to how to improve the overhangs.

Edited January 1, 2017 by Guest

[printerfan 5]

Okay, so I think I have ruled some things out. I was able to watch a print and saw the layer shift occur early in the print. So I know its not from the power flickering or from the stepper motors overheating. This is someone else's video, but this is exactly what I saw:

 

I assumed the belts needed tightened because to me they feel a little loose. I tried to tighten the screws, but they are already tightened to the max. I then moved the print head around while the printer was off and noticed it was quite stiff. Gave it some machine oil and now its moving much smoother. Not sure if this will resolve the layer shifting issue or not.

A video posted by Tom Saladerer mentioned that a good starting place for belt tension is to strum the belt and it should sound like an E Note from a Bass Guitar.

Is this an accurate test?

How do I know if my belts are loose?