Pleasant Hardware

Now that the filament spindle is operational (and that I have a little bit more time than the last 8 weeks), I continued to work on the Mecanum wheel project.

As you might know, 4 Mecanum wheels are needed to build a functional omni-directional chassis. So far I finished only two (at least two others weren’t usable due to failed prints, normally because of filament jams…).

One big problem is still, that due to ABS shrinkage, Makerbot fabrication tolerances and printing with 45° overhang, the holes for the ball bearings are always slightly too small.

Until now I used a Dremel to manually grinding the holes a little bit bigger (as seen here and here). The biggest problem with that (besides the boring work) was that when grinding manually, you never get the final holes exactly round.

Earlier this year, I allowed myself buying a nice, new drill press:

Ever since I wondered, if it would be possible to machine finish the holes for the ball bearings with it. I happen to have a 13mm drill (which is the OD of the 624 ball bearings), so the only thing I’d need would be a jig to position the Mecanum wheel resp. the printed hole exactly centered and horizontal under the drill.

So why not simply print such a jig?

Here’s what I designed:

I then screwed the printed jig on a piece of wood, adjusted it on the drilling table and clamped the whole assembly down:

Now that the filament spindle is operational (and that I have a little bit more time than the last 8 weeks), I continued to work on the Mecanum wheel project. As you might know, 4 Mecanum wheels are needed to build a functional omni-directional chassis. So far I finished only two (at least two others weren't usable due to failed prints, normally because of filament jams...). One big problem is still, that due to ABS shrinkage, Makerbot fabrication tolerances and printing with 45° overhang, the holes for the ball bearings are always slightly too small. Until now I used a Dremel to manually grinding the holes a little bit bigger (as seen here and here). The biggest problem with that (besides the boring work) was that when grinding manually, you never get the final holes exactly round. Earlier this year, I allowed myself buying a nice, new drill press: Ever since I wondered, if it would be possible to machine finish the holes for the ball bearings with it. I happen to have a 13mm drill (which is the OD of the 624 ball bearings), so the only thing I'd need would be a jig to position the Mecanum wheel resp. the printed hole exactly centered and horizontal under the drill. So why not simply print such a jig? Here's what I designed: I then screwed the printed jig on a piece of wood, adjusted it on the drilling table and clamped the whole assembly down: Long story short: It works great. But see for yourself: So here's the third Mecanum wheel: One to go...

This entry was posted on Friday, July 30th, 2010 at 18:15 and is filed under Designs, Experimental, Hardware, Movie. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.