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Custom Instrument Housing

I seriously can't stomach spending $400 to put a waterproof box on my pedestal guard.  I'm not questioning the quality of those things, I'm questioning whether or not I need it.  After some soul searching I decided that I was perfectly capable of making a small wooden box and coating it with epoxy, then painting it.  The details beyond that would work themselves out during implementation.

And so I began where I always do:  A sketch on a piece of scrap paper.

Having a pretty good idea what size pieces of wood were needed, I scavenged through my scrap pile and discovered a nice section of 1/4" plywood which was high-end stuff (no voids, many layers, nice and straight).  This project just got even more cheap since I don't have to buy wood.  I cut out what I thought would make a good size display and started playing with template positions.  I ended up with the plotter at left so that the media slot could open, and the Autopilot control at the upper right.  This would allow some space to mount a small switch bank or other item below in the future if I decided I needed it.


I decided to use basic butt joints throughout.  The epoxy will be stronger than the wood itself, and when thickened it fills minor gaps nicely.  In addition, I plan to add a few layers of fiberglass to the assembly when done, so the joints really don't need to be very strong.  They just need to support the wood well enough to assemble and act as a mold.



So, I cut out the pieces I needed.  I assumed a 4" box depth because it was a good compromise between avoiding cable strain and having a giant box clogging my view.  I wetted out all of the relevant surfaces, then put together a mix of thickened epoxy to bond it.  I clamped everything up very lightly in the center to remove a slight bow in the wood.  Note that I glued up the 4" slats the night before using a box building jig.  I'm building in sections to keep things simple.

Another design detail worth mentioning is my intent to have rounded corners.  The problem is, with really thin plywood there isn't a lot of material in the corner to route out.  My solution was to bond a 1/2" square block in the corner of all the joints.  This will not only provide significant strength, but provide additional material to support the corners after rounding.  The pieces are visible in the picture below:


After gluing up all the surfaces and letting the Epoxy dry completely I did some pressure testing on the box (nothing formal - I just pressed on it hard!) and was very happy with its strength.  As a result I decided to forgo the fiberglass cloth.  That saves a lot of time and hassle. 

I used a round-over bit on my router table to ease all the corners, then gave it a hand sande down to 220 grit.  At this point the box started to look really nice.  To waterproof the box I gave the whole thing three coats of neat Epoxy.  Now it looks not nice, but exquisite!  Of course, it's not going to stay natural; I need to paint it white to blend in with the rest of the cockpit.  But it almost looks good enough to keep as-is!

Next step is to remove the blush, scuff sand to prepare for painting, then give it as many coats as necessary of white paint.  I chose Interlux Brightsides linear polyurethane paint.  It was a bit tricky at first getting the right amount on and learning the roll and tip method.  As a result, I would need to sand it down and repaint to make things perfect, but overall it looks fantastic.  I'm pretty amazed.

Here is a picture of the finished product:
Custom "NavPod" I built from 1/4" plywood, epoxy, and Interlux Brightsides Paint.

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