MB 2X Circles aren't round

[hobbes]

It's 12:30 and i'm a little tired. I took many pictures, as I put in 6 hours worth of small test prints. I'll upload just 3 for now to showcase a concerning issue i'm having.

For all the prints, i'm using the standard 2X bed and nozzle temps (110 bed, 230nozzle). If there are better numbers for ABS on the 2X, please let me know. I know that my prusa operates just fine at 100 bed and 200 nozzle.

The tensioning of the belts and gantry realignment seemed to have helped, but it wasn't obvious right away. The first prints didn't seem to have been affected much from it, but the more i use it, the better the rounds are getting.

You will notice in all 3 pictures i have arrows pointing to thin walls. In every case, the walls are just 2 layers thick with no infill, even though they were all set to 100% infill. I have put samples from my prusa and from my old replicator 2 (which i don't own anymore) for comparison.





It's especially evident in this picture of my wheels. The wall is supposed to be completely filled out at the neck, where the axle gets inserted. Also, oddily enough, the print with 4 shells had more spaces between shells than the one with 2 shells.




It's not just limited to thin walled circles. On this chassis you can see that even straight walls are affected by this "no fill zone" problem.



Ideas?