Replicator 2 problem on making circle/cylinder

[Aleksandar Dimitrov]

Hi everyone,

that's my first post here as I'm trying to fix a printing problem on our replicator2.

What you see on the photo is a base of small chess figure which has terrible offset from circle. It is notifiable that the edgy effect appear symmetrically on both sides of the model. Additionally sort of a seal becomes visible too.

Do you guys have any recommendation I can follow?

Cheers

[Jetguy]

2 known issues on this model or series of MakerBot.

#1 The X axis belt idler must be lubed frequently or else it can spin the metal shaft and cut into the plastic end bracket resulting in a loose X axis belt. This is an overlooked wear and tear area and may require replacement parts if already damaged.
#2 The plastic linear carriage the extruder rides on depends on a molded section that grips the X axis belt. Heat from the heater and stress built into the plastic from injection molding can make this clamp section loosen on the belt. This results in backlash (lost motion) between the belt and the entire extruder assembly in X axis.

The way to check for number 2 is simply go the jog menu on the LCD and move the X axis to the center of the printer. Then, while still on that screen so the motors are locked attempt to move the extruder left or right in X and observe where the belt attaches to the carriage. If you see the belt stay still (motor is locked during this test) and the plastic carriage moves on the belt- you need a replacement carriage.

[Aleksandar Dimitrov]

Jetguy, thaks so much!

It is not #2 as I have just performed your instructions.

I was thinking of #1 since the beginning.. I have ordered this lubricant 

Will now check if the X axis belt idle has caused any damages on the neighbor.

Thanks again :) 

[Jetguy]

Oops, forgot one, loose pulley on the motor shaft. Since the motor shaft is D shaped, a loose setscrew lets the pulley rock back and forth as the motor changes directions resulting in lost motion (aka backlash).

The bad part on this is, the OEM MakerBot pulleys used smaller setscrews. They are a royal pain, and unless you have a good perfect sized hex key, the risk of stripping them out is high.
Replicator 2 and 2X both use 18tooth gt2 pulleys. Most other printers that look like a Replicator from other brands use 17th pulleys.
What I'm getting at is, if yours is bad or stripped, make sure you get the exact proper pulley. It has to be an 18t GT2 2mm pitch, 6mm wide, 5mm bore.

On Friday, March 16, 2018 at 1:14:29 PM UTC-4, Aleksandar Dimitrov wrote:

[chrono144]

Thanks @Jetguy for this!
I didn't realize how loose my Y axis idler belt was till doing this!
I put all new belts and it works so much better!