Mike. Compression of the front ‘O’ ring between the window and the bezel can be affected by poor design, too thin ‘O’ ring, too thin glass, too short reflector, too thin star, a different insulator. lol. With the el chepo light I mentioned above, the bezel would screw all the way in and the window would still rattle a little if I tap the light hence, forming a poor seal against water entry. You can source thicker ‘O’rings or ticker glass or change the LED to one on a Noctigon star, or sand down the bottom of the bezel till the ’O’ ring is compressed enough to prevent water entry. OR, it might be a lot easier to just buy a Convoy C8 and done. lol
EDIT: My statement about putting a ‘spacer’ underneath the star above was incomplete. To be specific, I mean a smooth, flat, clean, copper disc with thermal paste. Proper heat transfer must be maintained.
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WRT the switch, usually the switch boot is silicon rubber which is very durable. I wouldn’t worry too much about tightening the retaining ring too much.
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NO. a C8 flashlight would not float if dropped in water. lol. Unless of course, you attach one of those floatie lanyards made for cameras.
Thanks for your input Emma. Would four or five oring be better than second or three?
Before you do all that lubing dissassemble it a clean it. Most of our budget lights come from the factory with a supply of metal shavings included somewhere and all it takes is one to cut an o-ring or hold it away from the land. Dirt will do the same thing. Clean, lube , assemble, and bag it until you use it if you plan on submerging it.
I sold a C8 to a mate at work and he asked in passing if it was waterproof. Thinking he was talking about dipping it in the bath I told him try it. He came to work yesterday complaining as he reckoned the orings were perished and it let water in. I later found out he went diving and it failed at 10 meters. Lesson learnt.
It rains a lot here in the winter, and in my mind the weakest link for water ingress is the tail switch. Pop the switch, use Shoeglue (a pliable nonhardening glue) on the outside flange (the knobby side), build a ring around the knob and press down the cap onto the tail cap. Then run a thin bead of marine silicone caulk around the inside perimeter of the rubber cap where it meets the metal. Reassemble the clicky, turn down the retaining ring. I used a high pressure hose to spray at it, and nothing was coming through.
Silicon grease and Teflon tape works too in the threads, I’ve put them in eye dropper fountain pens and they don’t leak anymore in airplanes.
(I forgot who suggested the Shoeglue here when one of my switches popped out because of friction mount deficiency, but thank you sir.)
Shoe goo is as amazing as duct tape!! LOVE IT! (does it actually stick to the silicon boot or does it just form a thicker seal?)
first off , is this a good C-8 or some POS off ebay or from t-mart etc?
There are 6$ C-8’s and 26$ C-8’s
sometimes I will put three！
And/or you can use this as an excuse to start looking for “diving lights”
Definitely looked at some diving lights. But there’s got to be a way to waterproof this cheapie. I don’t think its getting through the threads.
I looked at one of my “better” c8’s. I still got it on eBay, but it has a solid pill, and seems to have been done by a knowledgeable individual. Arrived packed in a Styrofoam (ice chest like, but smaller) container!
It seemed to have a 1.5 mm o ring on the glass, and had a washer over the switch boot. So I got some of the convoy c8 42mm OD washers from FT ordered, and I’m planning on going to the local Ace today for a washer.
I took calipers to the inside of the bezel (?, where the o-ring sits) and got about 1.66 inches, so that is about 42mm. The cheaper light o-rings looked thinner, maybe 1mm
Hopefully that will solve the problem.
Zip lock bags work, I floated a DSLR and 2 lenses in a couple of them (one inside the other,) just to see if I could. You have to leave air in, gallon size. But they’re not robust. But even with a pinhole, I think it would give you quite a bit of time to grab the camera or whatever, as opposed to going straight to the bottom and getting wet enough to be ruined almost instantly
Great topic... My friend asked me about diving flashlight for diving/Spearfishing (without bottle), I wasn't able to give him some reference beside a Fenix (from memory...)
Technically, the sd10 has thicker wall and double O ring(... waterproof to 100m). I am just wondering if a standard IPX-8 2m would be usable for that kind of short duration diving session (not bellow 10m...less than 3mn)
The Fenix looks nice. I wonder how deep you could get a C8?
I went to Ace and Napa today. The 1 5/8 OD 3/32 diameter washer from Ace seems to have stopped the leak up front, and a regular 1/4” washer (I think for 1/4” bolts?) seems to have fixed the leak in the back. About $0.60 with tax.
I haven’t tried any of the other o rings I got at Napa or Ace. I got some 10x20x2 nylon washers off ebay, which I think might be better against the rubber.
Don’t sand the bezel until after you’ve added o-rings. I got it too short.
Napa’s dielectric connector grease is labeled 100% silicone grease. Ace has some, too
Sometimes the lights get assembled with the o-ring between the lens and reflector but it will seal better with it between the lens and bezel. Shouldn’t need to goop up the tail cap to seal it. A very small amount of silicon lube on each part will allow the parts to slip and the retainer to tighten sufficiently for a good seal. Over tightening can deform seals.