DIY Video Housing a success...

[Bobby_M]

Acording to the books,
To what depth would the schedule 40 work, I noticed that it has a max pressure rating of 180 PSI and Schedule 80 280 PSI. Another thing I found was that 1 ATM = 14.7 PSI. So would this mean in theory that the pipe can withstand aprox. 12 ATMs, Don't know if this is right or not. If this is true it would mean that max depth for the pipe is 363 Feet.

I'm planning a very similar housing. I was reading the specs on clear PVC (i wish I remembered the site), and they quoted similar PSI limits. However, they also showed implosion strength, which as about 25% higher than "explosion" pressure. The tubular shape actually resists outside pressures better kind of like how a keystone arch works. Either way, I'm starting with Sched 40 pipe and using 3/8" cast acrylic for the end plates.

I've also figured out that the best cement to bond acrylic to PVC is Weld-On #40. I'll be sure to share some pics when I finally get around to building. BTW, I have the Canon optura60 miniDV and I HOPE it'll fit into 4". If it doesn't, I'm just going to drop the bucks on some 4.75" cast acrylic tubing and hope I can make some of the money back selling housings to my buddies.

Bobby

 

[moneysavr]

Hi Bobby,
I am a road contractor in the warm times of year and do sewer work, so yes I have the book for pipe,The company is HARVEL= its speced under clear pvc!
www.harvel.com
their clear pipe sch 40 & 80 both are speced in the book I have,and should be on the web site.
clear pvc cool!
Brad

 

[ChillyWilly]

Weighting is easy too...

I put most of the weight internally. I made a mold of the inside of the housing and poured lead in it to make a weight that would fit inside. I took a piece of the PVC pipe I made the housing out of and cut it to the lingth I needed the weight to be. I cut it in half end to end so I had a short U shaped piece. I then took two flat pieces of PVC and glued one to each end of the U making the mold. I had some heavy duty aluminum tape that I ligned the inside of the mold with but I think it would work without the tape as a heat shield. I marked the inside of the mold with a line so I knew how far to fill it then melted some lead in a stainless steel measuring cup I bought at the local food store using a propane tourch and poured it in the mold. When it cooled it just poped out of the mold and I used some JB Weld to glue it inside the housing under the mount the camera sits on. It wasn't enough weight so I made the handles on the housing out of 1" diameter solid brass rod, that stuff is heavy. I drilled and tapped one end of each rod and screwed in a SS stud that would go through the "Wing" on the housing and a washer and cap nut held then inplace. I used foam bicycle hadle grips to cover the brass rod so it looked better and was easier to hold on to. All that was left was to add a few trim weights to the inside of the front of the housing so it would float level in the water. With the battery on the back of the camera my housing would float slightly nose up. I went to a local auto parts store and bought some of the tape weights they use to ballance tires and added a few at a time until the housing was level in the water.

This is what I was contemplating to do, but wasn't sure about the mold. I do have a piece of the PVC used but I thought that it would melt when coming in contact with the Hot lead. I will make a mold like yours and line it with metal tape.


Thanks for the idea,

 

[426Scuba]

I'm starting with Sched 40 pipe and using 3/8" cast acrylic for the end plates.

FYI: I don't know if you have the 3/8 acrylic yet and how much you paid, but .472 is supercheap from McMaster along with 1/2 or .708 is cheaper than 3/8. + is a lot stronger!

 

[Bobby_M]

426Scuba,

Actually, I hadn't purchased anything yet. I simply thought it was stong enough yet thin enough to cut easily. The design I plan to use doesn't rely on two or three latch points to hold the acrylic tight. I was going to mount the acrylic into a PVC coupling and it will be supported all the way around its edge. I may take your advice on the 1/2" though.

Moneysvr,
Yes! Harvel is what I was looking at. Notice that on the sched40, the 4" has a PSI rating of 110 while the critical collapse pressure is 169 PSI. I may be taking a leap by interpreting the 110 as internal pressure limit and 169 being the compressive pressure limit. http://www.harvel.com/pipeclearpvc-40-dim.asp
If I were going to pay for clear PVC, I might as well just buy cast acrylic. The pricing is pretty close and I know acrylic is much more machineable.

My camera does fit into 4" PVC, but I noticed that Lowes only carries foam-core which clearly says "not for pressure applications" right on the side. I guess I'll have to check out a plumbing supply.

Bobby

 

[Bobby_M]

1 4"sewer cap test plug
2-5" hose clamps
Set 4" o ring in cut short end of coupling,light amount of sealer / Glue lens in
pour lead mix with glass mix in saftey cap end with some glue /sealer to keep it in place.
I grease the weight cap end with oring so I can pry it on off

Moneysavr,
I have a couple questions about your design. If I understand the pictures and description, you use the test plug to create the pressure-tight seal in the rear. This is basically a plug that gets expanded by tightening the wingnut right? If that's the case, what is the purpose of the coupling with acrylic window? Thanks.

Bobby

 

[moneysavr]

Moneysavr,
I what is the purpose of the coupling with acrylic window? Thanks.

Bobby

Hi Bobby,
The coupling has a stop in the center and I cut one side off with some left for the lens and o ring to sit on, were I lay a o-ring and a bead of silcone glue not caulk then run a bead around the out side too. no need for clamps to hold lens ect,,the water PSI dose all the work.
The other end I use a sewer test plug inside of a coupling & back it up with and cap with oring its like a saftey and cap holds the lead too.
I will break it down with photos as I am doing a nother unit,
Brad

 

[Bobby_M]

Ok, I get it now. You're using the test plug as a backup seal. I think what threw me off is your use of acrylic on the back end since you can't see through the test plug anyway. Here's a good question, would you abort the dive if you noticed water getting in behind the plug or would you continue on knowing you still have the secondary seal?

 

[ChillyWilly]

Ohhhhhh,


I molded the lead finally all 13 lbs worth. I bought a Stinless bowl at Target for $3 and a good Barbecue Hot Glove. I created a mold using the remainder of the PVC and put aluminum tape to the PVC as a barrier. The mold was made of half a PVC and the end were made out of wood.
I heated the Lead in the bowl on a camp stove, thinking that it wouldn't melt it, but it did. I noticed lots of inpurities on the surface that I should have removed but if I used a strainer from the kitchen my wife would have killed me, lol. So I left the crap on top and poured it onto the mold......Yaiks......as son as I poured it the tape came of in some place and got stuck in between the lead....o well. I also noticed that the pvc got super soft and opened slightly, I should have supported the sides of the pvc to keep it from opening....O well close enought. After cooling I removed the piece of lead and it came out OK, not perfect from but nothing that couldn't be filed away. The mold was trashed after this, the PVC burned pretty nicely in the areas that the lead was poured. The shape was ok even thought it has a small flat spot since the weight of the lead itself flatened the bottom of the PVC pipe. Next time I'll make something out of Plaster or something that will withstand the heat.


So I filed the piece of lead and velcro 'd it to the housing, this would allow me to move if necesarry. then I cut a piece of plexi as a platform to the camera. This is still in the refining process but i had a dive the next day and wanted to test the housing out.


The Test:

I went on a 20 ft beach dive and loaded the camera and started filming, overall the weight was slightly negative and it tilted slightly forward, so the camera was always in the right filming position pointing down slightly. I think the weighing is ok, have to test further. After about 40 minutes i did noticed a slight leak, but very insignificant so it had no effect on the camera.

Just bought some 3M Quick cure Marine sealant and will use this to seal the outside of the rear window. This should take care of it.

Anyway I shot my first uderwater video and was able to show the family the video, so that was pretty cool. Looking forward to a boat dive with it to see how it does in the deep.


Anyway let me know if I can be of any asistance.

PS. wear a mask when you melt lead !!!! nasty

 

[moneysavr]

Bobby,
I cant see thru my rear pvc cap its white, But I am sure the test plug would take depth,
I just like to play it safe!
Walter,
sounds like your hard at it!
Lets see some video!
Good luck all,
Brad