UNDERWATER BOX FOR MAVICA

My First Digital Camera Housing

"You want me to do what?" Curtis said nervously.

"I want you to build me a camera housing for this camera." I replied. "Don't worry, I will guide you through the process"

Curtis obviously wasn't sure about building an underwater camera housing for the boss's camera. He had never done something like that before. What if his housing ruined the boss's camera?

I felt that it would be a good learning exercise for him and an opportunity to use the milling machine and other tools in the shop. If it leaked so what...leaks can be fixed....and the rule is .... It is not if a camera housing will leak, but when.

Why build and not buy....if you have to ask that question, you haven't been around my website much. Besides when I was housing this camera, there were no digital housings on the market. Even if they were, it just ain't right to buy when you can build. My wife and I had our own kids didn't we....At least I'm pretty sure of that.....

I chose plexiglass for the construction materials because I learned to work with it many years ago, you can see how to place the controls and glands, and you can see water in the housing. The seal was going to be a gasket made of gum rubber. That was good enough for a Rollimarine and my first movie housing.

At the time I did not have a good band saw so I had a plexiglass shop cut the main pieces of the box. I used 1/2 inch plexiglass. Partially for the wide gluing surface, partially for the strength, and partially for the weight as it was going to be positively buoyant anyway. It cost about 10 dollars more to have them precut. Curtis was only going to glue them together, make the pressure plate, install the glands, and fabricate the control rods to operate the camera. It was the off season and this was going to be fun for him....if a little nerve wracking.



Design considerations.

Minimum volume....use a box not a cylinder
Pressure on joints....use 1/2 inch plexiglass and make larger surfaces push flat
on box. Shear surfaces should be the smaller plates.
Minimum Controls...one to turn on camera one to click shutter
Seal gum rubber gasket
Draw latches for closure
Camera mounting tray attached to bottom removable plate




The ends were the smallest pieces so they go inside. This way compressional forces do not try to break the glue joints. The back and front are the largest and go on the outside. I sketched out the fit of the box parts and gave them to the plexiglass shop. They were ready in a couple of days. Here is how the ends, front, and back mated up. The picture is a bit crude but you get the idea. The parts were glued with thickened plexiglass cement. Use a weight to hold the plates in place when gluing.

The top was glued on after the other parts had cured. I recommend letting it go for several hours per joint.

The next part of the project was the entry port and camera tray. I did not want a hole through the housing to hold the camera in place so we made a plate with a tripod screw hole. the camera tray was made of 1/4 inch plexiglass. The camera tray was mounted to the bottom plate by a couple of 1/4 inch round hole bolts. We bottom tapped a couple of shallow holes in the bottom plate to receive the bolts that went through the camera tray. We attached a small piece of plexiglass to keep the camera from rotating in the housing. The tray was sized to just fit into the camera housing.

An additional function of the camera tray is to support the inside of the gasket.

Here you can see the camera tray attached to the bottom plate. You can also see the strikes for the stainless steel draw latches.

I purchased my latches from SPD. The ones I used were the CAC204x latch with a CAS200x strike. If they are not available, the CAC201x and CAS201x shown on the referenced URL should do.

Oh yea, It did leak. On the first dive, I had to hold the camera upside down so the water would not get to the camera. For the rest of the trip, I gooped the seal before each dive. In the picture you will see a red oval with two holes in the bottom plate.

It leaked because we only used one draw latch on each side the first time. There was not enough pressure to seal it up. This was my screw up not Curtis's. When I got back to the states, I changed it to two on the front and two on the back....no more leaks.

Here you can see the camera mounted on the tray. It is ready to slide in the camera housing and make final decisions of the locations of the control glands. We marked the locations of the holes on the housing with a Sharpy pen. Now for the control glands installation. They work great on flat surfaces. The gland consists of a thru hull fitting threaded 3/8 inch, a backing nut, an "0" to seal the housing, an "x or o ring" to seal the shaft, and a cover nut. They are available for under 15 bucks from Ikelite dealers. I just buy 1/4 stainless steel rod to make the shafts. Knobs are available from Tech America and other sources.

The first control was to turn on the camera. We put the camera in the housing and selected the drill spot on the top of the housing. A few minutes later the gland was in place. I turned down the shaft for Curtis, heated it with a torch, bent it, and added a little plastic screw cover from Lowes. It is shown on its side for clarity in this shot. It looks a little like a golf club. Push in and twist...the camera goes on.

The second control trips the shutter. A simple press on the lever and the camera does its thing. This gland was in the right side of the camera. Again I turned down the shaft, heated and bent it, and added a little plastic cover.

If you look closely, you can see the rust on the backing nut from the earlier leak.

After the first trip, I added handles to make things more convenient. I also smoothed down each and every corner with my bench sander because those sharp corners hurt.









Here the housing is complete...less the camera...what do you think I took these pictures with.

Total costs for the project were under $100 plus some fun labor. In spite of the initial leaks....the pictures came out great. The picture at the beginning of this page was taken with the Mavica as were the pictures that follow.

Enjoy

Tom

Year 2000 pictures with the Mavica