Intro: Underwater Housing for MiniDV
Well, I took a good look at the possibility that I'd be diving again anytime soon and figured that since I already sold off all my dive gear, this housing was just on the shelf due to pride. In an effort to get some of my clutter out, I put the housing and camera up on Ebay so that someone else might enjoy it. If interested check out http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260769233083
The auction ends on April 21. Good luck!
Scuba housings are not cheap to buy, but they are cheap to build. Home Depot parts + internet mail order + time = Housing for about $70 worth of parts. Start your cam recording, seal it in the housing, edit later.
This one has been down to 92 feet salt water and has made a total of 6 repeat dives with open/close cycles in between. In other words, I didn't just get lucky.
By the way, we also plan to use this at the beach and in the pool. Enjoy!
Step 1: Will Your Camera Fit?
If you have one of those full size VHS shoulder mounted bazookas, you might want to skip this project. 10" diameter PVC is not easy to find.
Take your cam into Home Depot or plumbing supply of your choice and sticking it in 3, 4, or even 6" Schedule 40 PVC pipe. Note, it MUST NOT say "cellcore" or "not for pressure applications". This will not take the pressure. You need real, solid, PVC.
My design uses 4" and most of the new compact DV cams will fit, I think. The new JVC harddrive cams might even make it into 3" which is SWEET.
If it will fit in 4" with a little room to spare for the tray, cool. Get the 10 foot length of pipe, three 4" couplings, and a can each of PVC primer and cement.
You'll also need Devcon 5 minute epoxy (buy a few, they're cheap) (two part that mixes in the nozzle) in the glue section and twelve 6/32 x 3/8" stainless steel screws (or allen heads) from the specialty hardware drawers.
Step 2: More Shopping
Head over to Mcmaster.com and order the latches and O-Ring:
Get three stainless compression spring latches #1794A43 for about $6 each. The O-ring you want for a 4" pipe is a #425 EPDM part number 9557K377. Unfortunately it's a 9-pack for $12. I bought mine elsewhere, but I forgot where.
The Acrylic ports were cut from 1/2" thick plates. I bought a 12"x12" piece from freckleface.com for dirt cheap. If you have another source, by all means.
Step 3: Overall Assembly
Since this is quite customized per camera, I can only give you general guidelines.
One end of the assembly gets an acrylic window glued in. This is the sealed or non-removable end (left in the diagram). This end requires a 1/2" thick acrylic disc cut into a nice circle. I put the 4" pipe on top of the acrylic and traced the circle twice, rough cut with a jig saw, then mounted it to the PVC pipe using double sided tape and used a pattern maker bit on my router table to make a perfect disc. I'm sure it doesn't have to be this perfect, but you'll use more epoxy if it fits into the coupling loosely. You might as well cut both discs at the same time.
Hint: leave the protective paper on the acrylic for as long as possible.
Make two of the following:
Insert the disc into the coupling until it hits the stop. Use a pencil to trace on the paper against the stop so you know how much paper backing to remove when you glue it in. I just used an exacto to cut that small ring of paper off. Run a thin bead of epoxy in the stop and also on the side of the coupling where the disc will sit. Push the disc in and put some weight on it. A can of soup works. Let it set up for 10 minutes, or overnight.
Keep in mind, I trimmed the length of my couplings but it's not exactly easy to make nice square cuts. If you think you want to trim them, Do it BEFORE you glue in the discs. NOTE, the faces where the Oring sits must be smooth so I used the factory edges of the coupling. Of course, if you have a milling machine, you can go nuts with this. My purpose was doing as much as possible with readily available garage tools.
One final tip on the gluing process. Use masking tape on all adjacent areas because the glue goes everywhere. It's much easier to peel the tape before the epoxy or cement starts setting.
Step 4: Open End Details
Notice that a short ring of 4" pipe is inserted on the opening end, just behind the acrylic disc. This serves as a backing because the water pressure wants to push this disc into the housing. In retrospect, it may have been better to mount the disc on the other side of the moulded in stop (hey, give it a shot).
As noted on the drawing, the air gap between the body and the backing ring must exist otherwise the Oring will not seal. I laid the removable cap down on the bench and taped some pennies to this edge to create the air gap. Put a small section (a 1-2" ring) of coupling on the body of the housing with the factory edge facing the closure cap. Then put your O-ring on. Put your housing down into the cap (the pipe will now sit on the pennies). Push your Oring down to meet the coupling. Then push your 1-2" ring down to hit the O-ring. This represents the perfect placement for this ring and should be glued here. By the way, this is much easier said than done. PVC cement gives you about 30 seconds to work. It also gets squished out all over the place. Remember the tip about masking off your non-glued parts? You can't wipe PVC cement off because it immediately starts melting the pipe.
One more note on the O-ring sealing surfaces: Before you glue anything, you have to make sure these edges are beautifully smooth. I used the leftover piece of acrylic to make a large flat sanding block. With a little spray adhesive, I attached some 400 grit sandpaper. Then I rubbed these sealing edges in a random motion, turning it in my hand often, for about an hour each. Sometimes there is writing stamped on the ends. You can remove this first with a file so you don't spend too much time sanding them off. Either way, you might even want to look at this edge with a magnifying glass. Just one pit and your housing will leak.
Step 5: Camera Tray and Retention Rails
It's gonna take some trial and error to figure out how wide to make the tray. You want the camera to fit between the tray and the top of the pipe, but also leave a little gap at the bottom for the tripod mount bolt head. A piece of stiff cardboard makes a good trial and error template. Once you have the right width, choose your finished material. I used a piece of 1/8" thick PVC sheet I had laying around. You can use metal, lexan, acrylic. 1/8" aluminum sheet would be nice, but 1/8" thick acrylic would be nice too. I added a nice touch by chamfering the bottom edges so it matched the contour of the pipe. This is probably just a bit of DIY tool masturbation so you may skip it, unless you like that sort of thing.
Put some masking tape on the top and bottom edges of your tray and then place it in the tube (clamp it down to the tube from both ends with a C or quick clamp if you have it). Cut some strips of PVC and glue them to the pipe just resting on the top of the tray. Once it starts to set up, you might want to make sure your tray is free to slide out and has not been glued in.
Note: leave your tray long for now, you can trim it at the very last minute so that the cap closes.
This tray setup really needs to be done before you glue the fixed end cap on.
Step 6: Getting There.
The attached image shows what the housing should look like just after gluing the stationary cap to the housing body (simple PVC cement just as if you were doing some plumbing in the house).
I'm attaching a repeat graphic here for emphasis and so I can talk about mounting the latches. I went a little overboard and routed some flats on the couplings in the locations of the latches so they would sit flat. I'm not sure if this was all that necessary but it adds a fine detail. If you don't have a router, you could probably do it with a rough file or a belt sander. Just make sure you clamp the cap to the housing so you're flattening the same spot between the cap and clamping ring in all three clamping locations.
Notice that in all cases, the mounting screws for the latches do not penatrate into the sealed housing. They are always backed by another layer. The 3/8" long screws will just barely get through the first 1/4" pipe layer.
I specified 6/32 x 3/8" machine screws but you could use sheet metal screws. It really shouldn't matter. Just make sure you pre-drill with a bit just barely big enough to get the threads started. WATCH the depth. I put a 1/4" depth stop on my bit to make sure I didn't ruin the whole project with one slip. It's a good idea to put a drop of epoxy in the holes and on the threads just before final assembly in case water makes it in.
I don't recall why I mounted the latches to the cap and the catches to the housing. I'd probably do it the other way around because I have to hold all three latches wide open as I'm putting the cap down.
Step 7: More Stuff...
I didn't describe much about the handles because you can probably figure them out on your own. You can use gate handles for a super cheap solution. The truth is, once you get this in the water (and hopefuly close to neutral), it can be steadied with two fingers. The motorcycle style grips I have are overboard. They are made of 1/2" schedule 80 PVC nipples with Bell bicycle grips from Walmart. They are glued to a 1/2" male street L, which threads into half a threaded female adapter which is glued to the housing. Everyone is amazed that this glue joint holds up and so am I. I actually made a concave in the end of the adapter so that it made full contact on the housing. I roughed up both pieces thoroughly and used PVC cement. I added about a 1/3 pound of lead shot to handles for trim ballast and it actually makes the housing just slightly negative. I would actually remove a bit to make it neutral but I epoxied it in.
Before painting, it's a good idea to run a bead of 5-minute epoxy at all the joints. That is, inside and outside the Acrylic to PVC joints and even the latch ring to housing body joint because if water gets in here it can make it passed the O-ring.
The paint is just rustoleum. Lightly sand the PVC first, apply a primer, sand again, 4 light finish coats. It gets really beat up anyway so you might want to leave it white.
Finally added a length of 1/2" wide webbing and spring clip to keep the housing with me during rough seas. The additional female adapter glued to the bottom of the rig is for an arm to attach my light cannon.
Step 8: Updated Design (V2)
Ok, so the V1 housing is still working fine but as a do-it-yourselfer I couldn't leave well enough alone. The first housing left a lot of space the rear of the cam so it wasn't as compact as it could be. Here's V2, which basically replaces the rear removable cap assembly with a simple acrylic disk. Notice the draw latch catches are screwed right into the acrylic.
I've sold this prototype to a willing beta tester who's only had it down to 10ft so far. A full depth test will be done in early January 07. My next build will use 3/4" Acrylic for the end window but I'm not sure if the additional thickness is even necessary.
Step 9: End Cap Details for V2
The first picture is really the key to this design. It shows how a simple, non-machined, O-ring groove is created. Remember that water pressure is always trying to push the Oring into the housing so the inner wall must stop it. At the same time, you must maintain a gap between the acrylic window and the main body so that it only contacts the Oring. I'll add detailed notes to all images on this page.