Print keeps shifting

[Shizuma]

Just recently I started having this problem where my entire print shifts on me, it doesn't do it all the time and it doesn't always shift in the same direction, though it always shifts directly towards one of the towers. Thus far I've checked the belts which look fine, and the cheapskate bearings look fine and the trucks still all seem to move smoothly, I've also tried adjusting the tension on the belts but the problem still persists, does anyone have any other ideas on what could be causing this?

[stonewater]

a print shifting is almost always a mechanical issue. you did not say which max you have. first check the effector platform and every single nut and screw, including the big nut that holds the nozzle to the effector. then work your way up to the cheapskates again and everything in between. if you have the V1 the old metal arm bearings (where the arms clipped to the cheapskates) were known to seize on the rods. that is what happened on mine.

Tom C

[Shizuma]

Sorry, I have the Max V1 with the trick laser carbon fiber arms (my originals did seize on the rods) I did check everything from the effector plate all the way back to the steppers and everything looked fine and everything moved freely like it was supposed to.

[dajay23D]

IME, print shifting can also be caused by bad stepper motors. Seems like symptoms of bad steppers is a bit of black magic. I'm not talking about obvious things like, it simply won't turn. What if you're motors are degrading or it's too old or too many hrs on them? Or you've simply overheated them one too many times w/out noticing? IME, steppers are very sensitive. You grind them or you ram your effector in one of your axis and they'll pretty much start to degrade. I would check your motors if you haven't done that, yet.

[Shizuma]

How would I check the stepper for this issue? Aside from it turning when power is applied, which it does just fine I'm not sure how else to test it for an intermittent issue like this.

I was also noticing another issue which may have been the cause, or it may just be a coincident that I haven't had prints shifting since adjusting it, but I noticed the printer was over extruding and getting globs of plastic stuck to the nozzle which would eventually come off and stick to the print and harden, my only though was that it was hard enough that the nozzle hit that and cause the stepper to slip, I've printed about 5-6 prints since fixing that with no problems.

[Eaglezsoar]

You should have a value called Z-lift in your slicer, what do you have it set at? Try increasing it to .5mm or 1mm and see if it makes a difference.

[Shizuma]

I have it set at .2mm, some of this globs that were building up on the nozzle and sticking to the parts were 3-4mm tall so the nozzle definitely would have hit them, and I'm using PEI so the parts weren't going to get bumped loose, I ended up dropping my flow rate down to 90% on a few prints which stopped the globs from forming and it seemed to have fixed the problem.

[Eaglezsoar]

I have it set at .2mm, some of this globs that were building up on the nozzle and sticking to the parts were 3-4mm tall so the nozzle definitely would have hit them, and I'm using PEI so the parts weren't going to get bumped loose, I ended up dropping my flow rate down to 90% on a few prints which stopped the globs from forming and it seemed to have fixed the problem.

It sounds as though you need to calibrate your Cold Extruder, the instructions are in the guide. I am glad that you have made progress to the point that you
are satisfied. Let us know if anything else occurs.

[Shizuma]

I had actually done that maybe a month and a half ago because I was constantly having issues with under extruding, but now it's flipped to over extruding.

[Eaglezsoar]

I had actually done that maybe a month and a half ago because I was constantly having issues with under extruding, but now it's flipped to over extruding.

It should not do either. Calibration is a pain and sometimes a different filament can cause the over and under extrusion because of the filament's grip on the extruder geared pulley
but you should be able to "get it close" for the majority of your filaments. You might want to try the trick of slipping a 4mm bolt under the spring of the extruder to tighten it up
a little and recalibrating but it should not be necessary unless you use a lot of different filaments.

[Shizuma]

I did try putting a bolt under the screw but it caused issues with one of the filaments I use, the hatchbox gold abs, that filament just seems to be way softer than other abs filaments, to the point that when I did that it distorted the filament so much it would bind on the Bowden tube so I took the bolt out, though now I'm wondering if I did the extruder calibration when the bolt was still in place.

[Eaglezsoar]

I did try putting a bolt under the screw but it caused issues with one of the filaments I use, the hatchbox gold abs, that filament just seems to be way softer than other abs filaments, to the point that when I did that it distorted the filament so much it would bind on the Bowden tube so I took the bolt out, though now I'm wondering if I did the extruder calibration when the bolt was still in place.

That's exactly what I mean. You have to calibrate for the "normal" filament and if you put the bolt in to tighten the spring, you need to change the calibration values for having the bolt in there.
Good luck with it and I know you will work it out.

[dajay23D]

How would I check the stepper for this issue? Aside from it turning when power is applied, which it does just fine I'm not sure how else to test it for an intermittent issue like this.

I was also noticing another issue which may have been the cause, or it may just be a coincident that I haven't had prints shifting since adjusting it, but I noticed the printer was over extruding and getting globs of plastic stuck to the nozzle which would eventually come off and stick to the print and harden, my only though was that it was hard enough that the nozzle hit that and cause the stepper to slip, I've printed about 5-6 prints since fixing that with no problems.

check out my thread here: http://forum.seemecnc.com/viewtopic.php?f=37&t=9270

Just focus on the part where I switched the motors around, where y becomes x, X becomes Z..etc. Don't forget to change your config files to reflect the swap. To be clear, you just swap wires. See if your parts shift w/ the axis. It was weird for me where my odd shifting happened in ALL the axis. I eventually got tired of messing w/ it and got new motors. Solved the problem. I realized I rammed the motor one too many times. Also, I had a strong suspicion it was the motors in the beginning, but I wasn't sure. That's why I posted. They're about $8-9/each. I spent about a week troubleshooting it and all i had to do was spend $25bux...

[MrJoe]

If none of the other approaches work take a look at your stepper motor current values in configuration.h.
I had mine set too high after updating firmware and the stepper motors (or stepper motor drivers) were overheating and shutting down briefly while they cooled off, causing lost steps and misalignment.
This solved my misalignment problem.