2016-10-14 (F) Weekly Summary

This week I'm still getting back on track with 2xCb+Mic so a weekly update is in order. You can head over to the show page and make sure you're up to date on the cyborg podcast. I believe everything I've talked about on this blog is now shown on the site.

Show page on Twin Cities Plus

I'm the maniacal looking one on the left

The whole week was work on the belt sander. This project was supposed to save time and sanity while sanding gears for the Clockwork Theremin project. It hasn't saved time. But it should save sanity.

All the parts were gathered and threaded rods were cut. Some of the old black printed parts were still around.

 Drive plates, pulleys and connectors

The overall structure was finally erected. Each pulley on the threaded rods can be moved so that a slightly different shape can be made. Making an isosceles triangle was the most obvious choice but having one long side may be the best configuration for this project. The plastic structure was too weak to keep the parts in place and more than one drive plate broke because of it.

Scalene triangle configuration

The last of the black parts were replaced with stronger revisions printed in plastic with no pigmentation. Changes to the shape were what strengthened the parts, not the change in plastic. These new parts also received an update in the download section so it's no longer possible to download the weaker parts. Of course, the stronger parts require more plastic.

Stronger parts printed for the project

Metal braces were added to the threaded rods to add strength. Tension from tightening the belt in place caused lots of pressure on the drive plate so the metal braces took all this pressure and significantly strengthened the form.

Sander with metal brace

Even with the metal braces, kicking the sander by accident will cause breaking. It's also a good example of the low infill used to print this part. After this accident, the parts were all printed with 50% infill which seemed to do the trick. Higher infill takes more plastic but makes it stronger.

10% infill exposed after and accidental kick

Friction between the drive wheel and the belt wasn't enough. Smooth plastic touching the back of a sanding belt just didn't have any grip. Numerous ideas came to mind, including cutting the rubber from a bike inner tube, but the simplest solution was small rubber bands. One would probably be enough but three were used, for good measure.

Rubber bands for drive wheel friction

All the parts were literally in place so a video was shot of the sander in action.

Sander conversion video

Friction between parts was too high. One drive wheel and the drive plate made prolonged contact during sanding. This caused both parts to melt and eventually friction weld. They were pried apart and the drive plate was salvage but the wheel was shot. One nice thing about 3D printing parts is that I don't have to wait for shipping on a replacement part.

Formerly fused fabrications finally freed

After blood, sweat, and tears, the sander was finally finished. Actually, it's autumn in Minnesota so sweat wasn't really involved but the other two were in there. Once metal spacers were added around each bearing the sander worked marvelously. If someone were to print these parts at home and buy the hardware store parts locally they could expect to pay less than $30 for everything. This doesn't include the cost of a power drill.

Completed sander

Sander being used


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