2016-02-05 (F) Weekly Summary

Printing spinners as one piece was nice but it did require a certain orientation and they were probably larger than necessary. To make a spinner smaller it was broken into identical halves. Each half had grooves where a grommet or washer could be mounted then sealed inside when the spinner was glued together. The grommet was meant to dampen the impact between the spinner and the post so wobbling, in any direction, would not be felt.

Half spinners

After the first print the model was shortened but the grommet holders remained. Until a good location was found it was easiest to have multiple places to mount the grommet. By bringing the grommet closer to the pivot point the spinner could wobble in a wider arc than placing it lower which would tighten the arc.

Grommet installed in shortened spinner

Trapping the grommet inside two glued pieces worked very well but when it was placed on a post it didn’t spin well. The model was broken up again to print in three pieces. By making the pivot point a separate print the finish was smooth and unbroken so there were no grooves or pits to snag the post.

Three part spinner model

Instead of gluing two halves together the three-part spinner needed a second phase of glue. First, the two grommet holding halves were sanded and glued together with a grommet inside. Next, the top of the glued parts were sanded as well as the bottom of the cap. Then the cap and bottom parts were finally glued.

Three part model assembled

When a workable spinner proved it could spin freely and the impacts could barely be felt it was modified to include an extension on one side of the top. This extension, like a baseball cap brim, was meant to collide with a protrusion on the lid. Since the protrusion and extension would only impact when the compass faced north the rest of the collisions would be against a soft grommet and not significant.

Three part model with tapper

A base, to hold the post, and a lid, with a protrusion, were modeled to fit inside a small clear plastic jar. The post was a long aluminum rivet which had been cut down and sharpened. The jar was a simple paint jar from a hobby store.

Spinning model for base and lid

All the parts fit together, although some of them had to be sanded or drilled in order to fit properly. These measurements were due to printer and filament inconsistencies. Once they were tweaked they were inserted into a jar. They all fit well.

Compass in a jar

The rest of the weekly summaries have been arranged by date.

First time here?

Completed projects from year 1
Completed projects from year 2


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