Report as inappropriate

I am using a makerbot replicator 2 and the setting I have keep making the knuckles too brittle. I have it set to 3 shells, infill at 0.2mm, shell at 0.2 mm. The balls all need to sanded down since they are not smooth enough to rotate freely around.

Now there must be more ideal settings, what settings did you use to make the knuckles?