Sunday, April 27, 2014

Cut New Shoulder Discs at Kelvin's

I've been thinking about how to fix the problem of droid #2 leaning too far back. I believe the problem is due to my filing the flat spot on the gas pipe a couple of degrees too high.

Filing a new flat spot isn't a good option, and I don't want to start over with a new gas pipe/flange assembly, especially since the pipes are JB Welded and pinned to their flanges.

Another option is to cut and drill new shoulder discs, with the outer holes used to bolt the discs to the legs staying put, and slightly rotating where the inner holes are drilled to attach the flanges to the discs.

Of course, this means exploding droid #2 to get the shoulder discs off the legs. Kaboom.

I needed to pay a visit to my friend Kelvin's house, so we could use his jigsaw and router to recut the shoulder discs.

There are four holes closest to the center, to attach the flange for the gas pipe. There are supposed to be six holes toward the outside of the disc, for bolting the disc onto the leg. On this disc, there are six extra holes that I somewhat mis-drilled and don't use. ("Those are speed holes. They make the droid go faster.") I won't be drilling the additional six holes on the new discs. Finally, there is a large hole for the motor wires to pass through.

I only need two new discs, but am cutting four in case I mess up.

I used a jigsaw to rough cut the circles, leaving a little material just outside the perimeter line for routing to size.

A router is used to trim the disc to the perfect diameter, using a technique Mike Senna taught me years ago. The disc spins on a nail, and as the disc is spun around, the router trims the edge flush all the way around.

The four new discs, along with their progenitor.

Next I need to use the original discs as drilling templates for the outer holes, and then I'll need to carefully determine how much to rotate the original discs in order to have the flat spot on the gas pipe better line up with the 36-degree tilt that R2 should have.

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