DIY Canister Light and Lighthead

[bcsean]

I used a Phillips bulb as well, and it seemed to sit exactly as the one padipro shows on his msn site without deepening the groove and using the same o-ring.

 

[Padipro]

How do ou deepen the groove on the mag lites? I do not have access to machinery here to machine it.

Thanks

I used a drill press and a rotory file. I set the reflector housing portion of the light on the drill press table, before it was glued to the battery tube, set the depth of the cut by adjusting the highth of the table and then ran the housing round and round against the file as the press was running until the groove was cut.

unfix8r...

Why do you suspect that deepening the groove was the cause of the flood? I've never noticed that the bulbs from different manufactures were any different, there's a specification that the bulb is made to inorder to be an MR-16. What is it that you found different about the Phillips bulb? I deepened the groove on my light and the only trouble I've had was cracking the bulb because of the O-ring I was using. It was very hard material and had a rather thick cross section. It would not compress enough during the dive to contact the lip of the reflector housing and stop applying pressure to the bulb. This resulted in the water pressure being directly applied to the edge of the bulb cracking it allowing water to past the O-ring. Once I changed to a softer O-ring with a thinner cross section the flooding problem was solved.

 

[unfix8r]

I used a drill press and a rotory file. I set the reflector housing portion of the light on the drill press table, before it was glued to the battery tube, set the depth of the cut by adjusting the highth of the table and then ran the housing round and round against the file as the press was running until the groove was cut.

unfix8r...

Why do you suspect that deepening the groove was the cause of the flood? I've never noticed that the bulbs from different manufactures were any different, there's a specification that the bulb is made to inorder to be an MR-16. What is it that you found different about the Phillips bulb? I deepened the groove on my light and the only trouble I've had was cracking the bulb because of the O-ring I was using. It was very hard material and had a rather thick cross section. It would not compress enough during the dive to contact the lip of the reflector housing and stop applying pressure to the bulb. This resulted in the water pressure being directly applied to the edge of the bulb cracking it allowing water to past the O-ring. Once I changed to a softer O-ring with a thinner cross section the flooding problem was solved.

I didn't think that there was a diffence in bulbs, but even minor changes in the bulb can change tolerances. I found some really cheap MR-16 Bulbs at Ikea, and found that they have a ledge on the surface of the bulb.... no way to use them for this light. The Philips brand seems to make theirs just a bit smaller (just so they fit into the Maglite head?) and doesn't require the grinding that other bulbs apparently do. It might also be that I opted for a compact beam, maybe the reflector is deeper and the opening smaller? I'm just guessing here.

BTW, Padipro, you should really investigate the recoiling cord... I haven't dived it yet (ear problems) but preliminary tests show it kicks butt over the straight-line cord.

 

[Tiny Bubbles]

Some MR16 bulbs ARE different sizes. I think I posted this before but Sylvania MR16 bulbs are too large to fit in a maglite head. I have one and it sits in there cocked to one side -- it won't lay flat. The groove would have to be cut wider to fit such a large bulb.

So far I don't think it matters much if the bulb has it's own built in lens or not -- as long as the total flange thickness is about the same. I did a couple of burn tests in a bucket with a Solux bulb (they have built-in lenses), but I burned that bulb out. Then I dived a few times with a Phillips bulb (no built-in lens), and the lighthead never did flood with either bulb. I'll order some more solux's & give them a try at depth. I like the way the higher color temp looks, even if they do cost twice as much and last half as long.

As for my self-retracting cord... So far, so good. I've never dived with a plain straight cord so I can't compare.

-Tiny-B.

 

[wk2000]

Great group-I have a couple of questions about the dive light I am building-

I am using 3" PVC conduit to hold a 10- D-cell NIMH pack.

1. I'm using the sealcon watertight cord glands. These suckers use a 1" NPT thread. The mounting hole for the gland is almost the same size as the C-cell maglight endcap. The endcap is also pretty thin, and consequently does not thread very well with the 1" NPT tap I have. On the inside of the endcap, there is no room to place a backing nut. My lighthead leaks here. I've tried a O-ring at the base, and Teflon tape, but no luck. I'm considering pouring a bunch of JB weld inside the cap and embedding the gland this way. Any thoughts?

2. The maglight lens business is very confusing to me- I'm using the z-battery glass, and I have two different brands of glass front bulbs- one from Phillips, and the other Sylvania -neither one requires any enlargement of the maglight head to fit an extra o-ring between the bulb and the lens. My light leaks at this site- Do I need a thicker O-ring? How tight should it be when I screw the frontpiece of the maglight down?

3. I also have a small leak at the main canister o-ring. I'm planning on fine sanding this to smooth the top off even more, but the Dive light companion book makes mention of be sure to use o ring grease. What is o-ring grease, and where does one get some if it is necessary?



Thanks- I'll post up some pictures if I ever get the thing to stop leaking!

 

[bcsean]

Sounds very similar to my plans. Explain what you're using with the 3" PVC. I want to know how you've done the ends, cause this is also my plan.

I'm also trying to figure out how to mount the watertight gland onto the light. I've thought about JB weld, but if the fitting every goes bad, it'll be quite hard to replace.

 

[wk2000]

I cut out a 3" round from 3/4 inch grey PVC sheet from M_C. Then routed out the edge using a 1/4 inch router bit and a router table. That was the bottom, and was pretty easy. The top is 1" acrylic, and was a major PITA. Cutting out the circle with the economy hole cutter in a drill press took HOURS- the bit would seize and bind, the chuck would fall off - it was awful. I would use thinner stock & laminate if I was doing it again, or use PVC for both ends. Drilling the 3/4 inch hole for the cord gland in the 1" acrylic, and routing out the recess for the toggle switch also a major PITA. Padipro and the DiveLight Companion guys are major machine shop gods- I'm more like a weekend Home Depot guy. YMMV.

Sounds very similar to my plans. Explain what you're using with the 3" PVC. I want to know how you've done the ends, cause this is also my plan.

I'm also trying to figure out how to mount the watertight gland onto the light. I've thought about JB weld, but if the fitting every goes bad, it'll be quite hard to replace.

 

[Tommygun53]

Great group-I have a couple of questions about the dive light I am building-

I am using 3" PVC conduit to hold a 10- D-cell NIMH pack.

1. I'm using the sealcon watertight cord glands. These suckers use a 1" NPT thread. The mounting hole for the gland is almost the same size as the C-cell maglight endcap. The endcap is also pretty thin, and consequently does not thread very well with the 1" NPT tap I have. On the inside of the endcap, there is no room to place a backing nut. My lighthead leaks here. I've tried a O-ring at the base, and Teflon tape, but no luck. I'm considering pouring a bunch of JB weld inside the cap and embedding the gland this way. Any thoughts?

2. The maglight lens business is very confusing to me- I'm using the z-battery glass, and I have two different brands of glass front bulbs- one from Phillips, and the other Sylvania -neither one requires any enlargement of the maglight head to fit an extra o-ring between the bulb and the lens. My light leaks at this site- Do I need a thicker O-ring? How tight should it be when I screw the frontpiece of the maglight down?

3. I also have a small leak at the main canister o-ring. I'm planning on fine sanding this to smooth the top off even more, but the Dive light companion book makes mention of be sure to use o ring grease. What is o-ring grease, and where does one get some if it is necessary?



Thanks- I'll post up some pictures if I ever get the thing to stop leaking!

Im not sure but can you get the sealcon connectors with 3/8" NPT or maybe 1/2" npt ends?But before you go buy another mag,I would just try to seal the inside with 100% silicone or JB weld.

As far as the O-ring grease you refering to, it is just silicone grease and you can pick up a small container at any dive shop.

When you say your lighthead leaks,did you break the bulb housing?What size O-ring do you have in there? I just used the 2-133 in a 60 durometer which is a little softer than a standard O-ring at 70 durometer.

-Tom

 

[wk2000]

No, I didn't break the bulb housing. I'm using the bulbs with a glass front. I'm not sure what diameter the oring which sits on top of the bulb is, since I made it myself from the M-C O-ring kit. Its 70 durometer. I'm still trying to understand Padipros instructions about how things fit together.

 

[Padipro]

wk2000...

You said that you made the O-ring for the mag-lite head from O-ring stock. I've done this before myself and have had mixed results. It's difficult to get the measurement right when making an O-ring that fits on the inside of something. It usually turns out just a little to small to seal properly. The O-ring must be large enough to seal against the outside walls of the reflector housing as well as the lens and bulb. Also make sure that the mating ends are perfectly aligned and that there is no excess glue squeezed out. This is critical as misaligned ends will allow water past the O-ring and the excess glue forms a ridge that will do the same thing. My suggestion is to go to a hardware store in the area and try to match up an O-ring with the mag-lite. I did this and found an O-ring that fit perfectly and has worked flawlessly every time. If the O-ring just drops into the top of the mag-lite then it's probably to small, it should be just a hair to large to just drop in and therefore will need to be pushed into the reflector housing as the retaining ring is screwed down forming a nice tight seal. Make sure to take the light head along with you to check the fit. The retainer ring should screw all the way down on the reflector housing just like it did on the flash light before it was modified. Also look at the front of the light head when everything is in place and assembled. There should be a nice black ring all the way around the glass lens indicating that the O-ring is sealed against the lens.

As for the Sealcon fitting leaking, you said that you installed an O-ring under the base before it was installed in the light head end cap but did you counter sink the surface of the end cap to allow the O-ring to seal and not be squeezed out? this is very important as it gives the O-ring something to seal against on the sides. If you don't counter sink the area around the hole it will usually leak regaurdless of how much thread tape you use.

If you're worried about the material thickness of the end cap and how it will hold I'd suggest filling the end cap with JB Weld first and then drilling and tapping the entire thing. That will give you a nice thick surface to tap and for the threads of the fitting to screw into. If you've already drilled the end cap just put a bit of tape over the hole before you fill it.

The Acrylic is a PITA to cut. It melts very easy so as you're cutting it the heat from the saw blade melts the stuff and causes the blade to stick. I found it was easier to cut the stuff with a hand saw as close to the shape I needed as possible and then, using a disk sander, sand it to the final shape.

Good luck and let us know how things work out.