Banding Fix for Robo R2

A while back, I posted an issue with my Robo R2 where I had severe banding on all of my prints. I had a bent Z Axis Rod, which Robo replaced free of charge. This is NOT intended to correct severe banding!!!!

However, I did still see an issue (I think this is a design issue, on several levels) where I would see a rhythmic banding on my Robo R2's (I have two). They both showed the exact same pattern. So, I revisited the printer stiffener block that I made to correct the Z Axis issue, and found that it fixed the horizontal banding shown here as well!

To me, The lower Z Axis motor and bearing rods are mounted to an injection molded angle shelf... Further more, the plastic shelf has bolt holes where the bearing rods slide into the bottom (and the top). It appears they originally intended to thread and bolt the Z Axis bearing rods in, but probably had an issue where the threading process was making the rods wider on the ends, so they omitted the bolting of the bearing rods. If the bearing rods were secured to the top and the bottom angle plates, maybe they would have been stiff enough to not cause this issue. But, we have what we have... and sometimes we just need to fix it ourselves.

The print easily slides under the Z Axis motor, and if your printer is calibrated..... You should get a part that is 2.900" tall. I did re-level my bed(s) and reset my Z Axis offset(s)... not sure I had too, but I did for safety

Good luck

PS: Also, incase there is an issue with the files... here is a Thingiverse link:
https://www.thingiverse.com/thing:3564800

 

I was fighting with this issue since I got my R2. Finally found that file and printed the support tower. Much cleaner prints now.

 

After many attempts to fix my banding issues (using the printed guide block noted above, a real bearing, numerous speed and slicer settings), I gave in and bought a replacement Z motor/lead screw from PartsBuilt.com. Jonah was great - apparently there was a QC issue with motors they had on hand and he ordered a new batch. I'd received it within a few days of it being sent out. AMAZING difference in quality! Replacing couldn't be easier - while Jonah sent full instructions from Robo, it can be summarized as:

Raise the printing platform and remove the bed.
Remove the snap in cover to give access to the electronics
Sharply lift up the two rear sides of the base plastic piece the snap in cover was connected to. (it angles into the front piece, above LCD)
Unplug the lower z stop and zmotor connections
Unscrew the bottom two screws on motor/platform and carefully guide unit underneath hotend assembly. (you can move hotend out of way to make it easier to remove the assembly)

Pull out guide bars and unscrew leadscrew from platform (I used a rag to protect my hands when manually rotating the screw)
Four small screws hold the motor to the base of the assembly.
Reverse process to put it all back together.
Be sure to lubricate the new leadscrew before using. While I was at it I cleaned the guide rods and wiped fresh lube on them too.

9/10 update: I noticed on the occasional fast rise or lower from the platform the motor made a shrieking sound (no joke, really awful). In actual printing operation it sounded fine. Turned out to be a firmware issue. I'd gone to the github site and tried some later non-release versions and saw that one of the "fixes" was a reference to change for faster platform movement, and another reference somewhere to sound. When I went back to the official release, no more sound (and the loss of the fast movement isn't a concern.) I'm also happy to say that the banding issue is fully resolved - no more lines!