DIY Canister Light and Lighthead

[Padipro]

Okay, I am getting close to finishing... The light isn't pretty to look at yet!! My biggest issue has been sealing of the lighthead... it really wants to leak through the lens cover/ threads.
Padipro, do you have to sink the bulb in deeper into the lighthead? I imagine that the bulb is sealed better than any other part of the flashlight, so getting water from going around it and into the lighthead tube seems like the biggest issue. Diver0001 asked the same question I have... can the rubber oring be in direct contact with the bulb?

Also... do you recommend Teflon taping all threaded surfaces, or will that be a waste underwater?

Yes, you need to deepen the groove in the reflector housing so that the added O-ring, when installed on top of the bulb, will sit down inside the housing far enough so only a very small portion of the O-ring protrudes above the lip. I can't tell you exactly how much to deepen the groove because that all depends on the size of the O-ring you're using. What you want is for the glass lens to contact the O-ring just enough to form a nice black line on the lens when the retainer ring is screwed down all the way and holding everything together. You don't want to much of the O-ring sticking up above the lip though. This will cause the bulb to crack under pressure during the dive and the light head will leak. You want the lens to compress the O-ring only slightly during your descent, maybe 1/32 or so of an inch, and then contact the lip of the reflector housing. This will stop any further compression and the posibility of cracking the edge of the bulb. I had trouble with this when I first built my light. I changed the type of O-ring I was using to one made of softer material and it solved the problem. The O-ring should be in contact with the bulb inorder to seal the light. I haven't had any trouble with the heat effecting the O-ring, like I said before the surrounding water will dissipate the heat well enough that you'll bearly feel it even if you touch the light head to your face when the light is on underwater.

One thing you have to make sure of is that you are using the type of MR-16 bulb that has it's own glass lens attached to the opening of the reflector. If you can touch the actual halogen bulb inside the reflector it's the wrong type. This lens will hold the added O-ring in place and allow it to form a good seal.

Along with the teflon thread tape I also used an O-ring under the base of the strainrelief fittings. Counter sink the surface around the hole the fitting is installed in just enough for the O-ring to seat and this will make a great seal. I've never had trouble with the fittings leaking using this method.

 

[unfix8r]

Gotcha. I have been encountering some difficulty in obtaining orings of the right size, but I think it will all com together for a dry run next month. I will email pictures to your MSN group upon completion. Thanks again, Padipro.

 

[extreme]

My c-cell lighthead did not need any extra groves that you mention. I have had the light to 150' no problems. The bulb and orings, everything fits fine.

Extreme out.

 

[Padipro]

My c-cell lighthead did not need any extra groves that you mention. I have had the light to 150' no problems. The bulb and orings, everything fits fine.

Extreme out.

Post some pictures of the light head and explane how you did it. If you can show others how it's done and that it works you'll save some people a lot of time and effort.

 

[in_cavediver]

I have actually been working on several homebrew lights specifically for my UW video housing. After seeing all of the posts here, I thought I would share my successes/failures and ideas. Here's a site with all of my DIY type projects:

http://tools.ecn.purdue.edu/~loganm/hmdive/

To date, I have made 3 lightheads, 2 MR16 and 1 MR11, all from scratch using 6061 round stock. (my skill have dramatically improved from #1 to #3). I am using a 3/8" NPT compression coupler, bored out and an O-ring to seal the cord (and it has worked flawlessly with SJOW 14 cable).

On the lens side, I am using 3/16" Pyrex round for McMaster-Carr due to the high wattages of the bulbs I run. (75-100 watt). I did a price check locally and it was actually cheaper to order the borosilicate glass and get it round than it was to buy it locally and have it cut. That coupled with an appropriate O-ring and no leaks.

I am working on the new canisters. I have done all my testing using another canister but with a dual 75-100 watt lightheads, a single 12V 7A/hr battery just won' cut it. (Actually, it would damage the battery due to excessive current draw)

I have opted to stick with the 12V 7A/hr batteries mostly out of convience. I have 4 already, 3 chargers and inexpensive supply source.

I just got in the 5" electircal conduit (10' length) today and got it rough cut to size. I play to bond a PVC bottom on it and use an acryllic top plate. (Almost identical design to what's in the Airspeed press book).

I just wonder if others have had difficulty with this step of have any reccomendations? I plan to use a CNC mill to make the end caps from flat sheet stock and then fine tune the fit.

Mike

 

[Padipro]

Hay Mike,

Nice design. I wish I had access to a mill or lathe, sure would have made things easier.

I'm not exactly sure what part you're refering to when you say difficulty but if it's the top, or lid, to the canister it was a little challenging to drill, tap and then machine out the switch hole.

If you haven't already done so take a look at my MSN site for some pictutes of the light I made. The instructions for building it can be found in the documents section, and if you have any other questions just PM me and I'll be glad to answer them.

Again nice job.

DIY Light

 

[Tiny Bubbles]

Reflector groove? Not needed.......My c-cell lighthead did not need any extra groves that you mention..........The bulb and orings, everything fits fine...........

I'm also building a C-cell maglite based canister light. I picked up an assortment of MR16 bulbs, and they are not all the same! The Sylvania bulbs are slightly oversized, and will not fit without boring the groove out to a wider ID. The Philips, Solux, and Ushio bulbs drop right in and are loose enough to rattle around (I ordered the additional o-ring but haven't received it yet, so I can't say if the groove needs to be cut deeper or not). The Solux has it's own built-in lens, but none of the other bulbs that I have do. The "divelight companion" book says you have to break the lens & pick out the shards in order to use it, but one of the DIY webpages says you should only use the bulbs with the built in lens -- and leave it in there! There is some contradicting information out there.

About the end cap:
I'm using the plastic cord glands with the spiral strain relief from mcmaster-carr. The part that threads into the end cap is 1/2" NPT. Rather than just drilling a big hole & epoxying it in there, I took a brass 1/2" NPT female coupler & turned down the OD on the lathe as thin as I felt comfortalbe taking it, in order to make a threaded bushing. Then I bored out the ID of the end cap to match it. I plan to coat it with either epoxy or loctite 515 flange sealant and press it into the end cap so the cord gland can have something good and solid to thread into (and unthread from if the cord ever needs replacing). I'll try to post some pictures soon & let you guys know how it goes.

 

[Padipro]

Tiny,

I haven't seen the Dive Light Companion book so I'm not sure exactly how they discribe building the light head. I do know that the light head I built uses the bulb with the lens installed on it. It helps hold the added O-ring in place. Without the lens the O-ring might be able to compress inward from the pressure and unseal the light head. Have you taken a look at the pictures on the MSN site? There are a lot more pictures showing exactly what I did and how I did it, and if you need more info I can always take more pictures of and post them on the board.

Good luck and post some pictures on the MSN site for others to see.

 

[Tiny Bubbles]

Here's a photo of some stock & modified 2C maglite & plumbing parts, and some bulb boxes, a TP61 socket, and a sealcon plastic cord gland with strain relief...

Turning down that brass coupler was the easiest way for me to "thread" the end cap to accept the cord gland...

 

[Tiny Bubbles]

edit: I read the book again, and where it says to break the glass lens out, it's not talking specifically about maglite-based light heads.