Community challenge #10: Milling plastics (closed)

Whew - sliding in at the last moment. Did not start this project with the competition in mind, but the milling plastics competition has brought out some really interesting “make things work” entries so I figured I would throw mine in as well.

So I have an application for remote sensing and data collection in a marine environment. The intention is to capture forces, acceleration, and angles for human powered watercraft aka rowing shells, sprint canoes, surfskis, outrigger canoes.

Requirements are:

(1) needs to adapt to multiple environments (on hull, on oar, on paddle)
(2) needs to be waterproof! Somewhere around IP-68+
(3) needs to float - just in case
(4) needs to have a viewport to see LED status
(5) needs to be easily (but not too easily!) removable! for data download and recharge
(6) housing needs to pass bluetooth - no aluminum shell!

I had a Thunderboard Sense 2 development kit lying about to use for proof of concept so off to Fusion 360 we go for a housing to protect it.

a HDPE housing, a silicone gasket, a cast acrylic lid, and a UHMW mounting clip.

Designing the housing was quite straightforward other than some deep small holes for the M1.5 screws but designing a clip that would retain the housing that could release AND be machinable took a bit of pondering and fooling around. The clip will remain attached to the boat/oar/paddle and the housing would be removable. Eventually I settled on a slide-in style clip that would have a flexture to allow the retaining tabs to hold the housing in place. Machining could be done from the bottom of the clip to create the overhang and the flexture at the same time.

Once that was done it could be flipped and the inside of the clip could be pocketed out.

CAD done, off to machining. Again housing and lid pretty straight forward operations. I looked into machining the silicone gasket but it looked like I would have to freeze it with liquid nitrogen or some such equivalent so back to the craft knife and punches it was.

Machining the clip was the interesting bit (and also overlapped the competition) so I took photos.

Clip bottom complete

A little onion skin

Flipped, taped down, and edge finding the X and Y edges

Tabs looking OK!

Test fit before removal

It fits!

Mid clip-in

In mid-flex

And some preliminary testing of course

It floats!

Submersion test

Design files up on CutRocket! I hope someone finds the case/clip/flexture ideas useful!

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