Shifts in first prints off newly built kit
Hi all,
I'm hoping somebody will be able to help me. I just built my first MK3S and did a test print of the Prusa logo and whistle, but my prints don't come out right. It looks like there's some layer shifting happening?
https://photos.app.goo.gl/VEaqQtavtq9ikWT26
I did a second print of the logo as well, at 80% speed, and that had very similar problems. Judging from the pattern on the bottom it looks like it occasionally... moves too much?
I'm not entirely sure what to do and would appreciate your help. I wanted today to be exciting but now it's a bit of a bummer. 🙁
Best Answer by dgbonomo:
I was reading articles on the forums as well as elsewhere on the internet, and further tightening both of the grub screws near both of the belt motors seems to have done the trick. I thought I already had them pretty tight, but I guess... not? For the first test of today I reprinted the Prusa logo and it came out almost flawlessly. I will do another, longer test - something in the 2 to 3 hour range - and report back when that's finished. But it looks like this may have solved it.
RE: Shifts in first prints off newly built kit
Details that I forgot to add:
Firmare version 3.5.3
Y-Distance from Min:
- Left: 11.16 mm
- Right: 11.13 mm
Measured skew: 0.02°
0;0 offset:
- X 1.23 mm
- Y 0.66 mm
Belt tension:
- X 262
- Y 289
I have at least checked that the belts are parallel. I made sure of it while building, and checked again today, and they are.
RE: Shifts in first prints off newly built kit
I was reading articles on the forums as well as elsewhere on the internet, and further tightening both of the grub screws near both of the belt motors seems to have done the trick. I thought I already had them pretty tight, but I guess... not? For the first test of today I reprinted the Prusa logo and it came out almost flawlessly. I will do another, longer test - something in the 2 to 3 hour range - and report back when that's finished. But it looks like this may have solved it.
RE: Shifts in first prints off newly built kit
Okay, I can confirm that solved it. Amazing what a difference tightening two sets of screws can make. I've updated the gallery with today's successful prints as a comparison. Anyone else who runs into this issue, double-check that you tightened those grub screws well!
RE: Shifts in first prints off newly built kit
Flat First: Drive gears must be tightened flat-first.
1) Start with both set screws fully loosened so the pulley is free to spin on the motor shaft.
2) Align one set screw dead center with the flat on the motor shaft, slowly tighten the screw until it fully contacts the flat surface.
3) Torque the flat set screw to spec.
4) Now tighten the jam set screw, and torque it to spec.
Once tightened, never touch the flat set screw unless the jam screw is first fully loosened.
Why Flat First? Set screws have flat ends. If you tighten the jam screw first the set screw on the shaft flat doesn't fully contact the shaft, only one small edge of the screw surface is biting. Reversing torques can easily shift the shaft to a position the flat screw no longer contacts the shaft. This lets the jam screw wriggle loose. And after a while, vibration loosens the screws until the gear is free to rotate.