Shrunk and reprinted pinions for the Orbita

AUTHOR: Philip Chin

On Monday, we were working though some issues with the gears for the Orbita not moving smoothly when fully assembled. This was from a combination of issues of the pinions not being straight while spinning. One of the solutions was to shrink the gear part of the pinions so there would be less chance of hitting the walls of the Orbita. The two versions were made - one for 96% and one for 98%.

Key learnings

In Fusion 360, I created an Offset Plane on the top on the gear part of the pinion and used that to split off the gear part from the rest of the pinion. I did it this way because I only wanted to shrink the gear part and not the shaft of the pinion. The dimensions of the shaft needed to stay the same.

Then I reduced only the gear part. Looking back on the timeline, I noticed that I did a Uniform scale. I probably should have done a Non-Uniform scale with just the x-y plane. The change in the height is probably small enough that it's not a big deal.

Since the gear part was reduced, the hex shaped hole in the center was also reduced. The hex shaped hole needed to be widen back out so the acrylic nut would still fit. I did an Extrude/Cut to widen the hole.

I tried to be clever and add some extruded cut text to identify which pinions were reduced by 96% or 98%.

This actually didn't work out as well as I expected because supports covered the area with the text.

Orienting the pinions on the build platform was really important. Supports were touching the gears for the initial pinions. This added a lot of extra clean up work. For this print, the gear parts of the pinions were aligned facing up with a slight tilt.

Blockers

I had to hold off reprinting the pinions for a day because I couldn't find the tray for the Tough 2000 resin. Logan tried to reinstall the new pinions into the Orbita but new acrylic hex nuts had be made. There were some issues with the laser cutter but that has been resolved. I didn't have the metric drill bits yesterday to drill the M3 set screw holes into the acrylic hex nuts. I'll ask Andrew for the metric drill bits the next time I see him. I also asked Dan to order a set of metric drill bits.