anelok: main case, top: corners [1/4]

Werner Almesberger werner at almesberger.net
Sun Dec 1 20:17:59 EST 2013


I updated the 3D model of the case top and made a piece from acrylic.
It came out nicer than I had expected and there was no trace of the
Z-axis problems that plagued the Y-Box:

http://downloads.qi-hardware.com/people/werner/anelok/tmp/case-top-inside.jpg

This is with some manual cutting and scraping (and an ugly cut from
when the knife slipped), to make room for the corners of the module.
This drawing illustrates the problem with the corners:

http://downloads.qi-hardware.com/people/werner/anelok/tmp/corners.pdf

"A" is what we want: make a pocket in the case where the module
with its very pointy corners will fit.

Unfortunately, the mill can only make round inside corners, with the
radius determined by the bit we use. This is shown in "B". I'm using
a 1/8" (3.175 mm) endmill, so the corners are far too round for the
display module to fit.

This can be fixed by milling into the corner, creating a so-called
"dog-bone". In its least intrusive form one cuts diagonally, as shown
in "C".

Unfortunately, we have a wall there on the top side and we're already
taking some liberties by milling a bit into it. This brings us to
solution "D", where the extension is only on one side. This needs a
larger hole than the symmetric variant.

I didn't include dog-bones in the CAD model yet but did the
excavation manually. Hence the mess. Since this area will be painted,
I hope that the dog-bones will be as good as invisible in the final
design.

This is what the raw case looks like with Anelok inside:

http://downloads.qi-hardware.com/people/werner/anelok/tmp/case-top-transp.jpg

Since I don't have a bottom part yet, I had to use a clamp to hold
the PCB in place.

Alas, while struggling some more with the corners something snapped
and the display module started to get warm and to flicker. Today, I
couldn't get it to turn on at all :-(

Next: window cleaning.

- Werner



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