o rings for mag light conversion

[rescue15]

I know someone posted o ring information in a light head conversion. I just spent the last 2 hours looking for the thread. Can someone post what o-rings they used to make the mag light conversoion water tight? Do I need to beef up the OEM o-rings or will they work as is? Thanks

Steve

 

[Packhorse]

1st is the tail cap O ring. This is replaced with a NBR 70 124. Not sure what all that means. NBR is the material 70 is the hardness and 124 is the size in imperial????
Next is the lens O ring and the bezel O ring. These have been changed to NBR 70 48mm x 2mm I assume its 48mm ID.

 

[h90]

AS 124 is 31.42x2.62 mm (IDxCross-section)
Is it possible to convert a mag-light?? I have a large one, not original made in asia/very cheap, that would make a nice diving light if possible to convert.

 

[rescue15]

Hey packhorse.

I'm good on the NBR 70 124 but the NBR 70 48x2 is puzzling. I found a mail order place for the o rings but the metric sizes are no where to be found. Do you have an SAE conversion?

Thanks, Steve

 

[h90]

Hey packhorse.

I'm good on the NBR 70 124 but the NBR 70 48x2 is puzzling. I found a mail order place for the o rings but the metric sizes are no where to be found. Do you have an SAE conversion?

Thanks, Steve

If you need metric sizes, you can drop me an email, we have a lot of stock/can produce them in NBR, Viton, EPDM at single pieces.....

 

[Steve in Seattle]

You can always skip the rear o-rings altogether and just JB weld (or better yet Alumaloy braze) it solid. Less o-rings = less failure points.

I'd also suggest potting compound for the switch area once you test it and everything is working fine in the hand unit... that stuff will help support the case by filling in air pockets, and completely waterproof any PCB or solder points in the unlikely event of a water seal breach. Just mix it up like epoxy and pour it on... it'll settle into anything and set up in 24 hours. I bought a small supply of the stuff years ago and love it for weatherproofing any electronics that'll see vibrations, pressure, oil, coolant, or water. Back-filling cable glands with the stuff is a perfect application BTW.

It really is strange to me to see all these underwater lights and gear made by divers without mention of potting compound and brazing compounds. Cheap and massively effective to make your stuff bomb proof. I'd wager it possible to ziplock a battery pack and harness/cable, fill it with potting compound, and have a custom-canister that'll run to 500+ feet (the head is obviously another matter, but you get the idea).

Just something to think about.

Alumaloy home
Clear Encapsulating and Potting Epoxy Compound > RoHS Compliant (I use black, but you may prefer clear... imbed a few LEDs and make it a glow stick ).

 

[Steve in Seattle]

Two catches:
- don't use potting compound in/on a moving switch, it'll stick
- don't use potting compound to seal in a transformer... it's "supposed" to be fine, but one project I used it on showed decreased power output... I wasn't sure if it dampened the fields needed or if there was heat retention that compromised the wire coating. I'd hesitate to use this "inside" HID ballasts, but would be fine if the ballast was sealed off first then encapsulated... like I said, it gets into the smallest of cracks.

 

[rescue15]

What is potting compound?

Never mind, I found it...If you seal the gland with it how would you replace the cable if it needs it? Seems to me you would have to scrap the gland and start over.

Steve

 

[Steve in Seattle]

It's an epoxy specifically designed for encapsulating or "potting" electronic circuit boards for hostile environments.

It's nearly bomb proof, water tight, electrically inert (insulator), yet thermally conductive (to prevent overheating). Most are acid/base/alcohol/water resistant as well (PCBs and solder have lots of acid sources).

If you ever bought a small market "niche" electronics gear it may also be on there to obscure the view of the circuit paths or contant pickups... its a fairly good safety measure for obscuring the inner workings of devices (to deter tampering or reverse engineering).

Great stuff, not that expensive considering, and provides great waterproofing and pressure resistance to containers like flashlights

 

[Steve in Seattle]

Never mind, I found it...If you seal the gland with it how would you replace the cable if it needs it? Seems to me you would have to scrap the gland and start over.

That's the catch... its really a more permanent design for really hostile environments. Good for "black boxing" a PCD and wiring harness once all the soldering's done, but if you seal it to a container you can pretty much expect they're bound for life. No reason you couldn't place it all in a ziplock, have the wires come out the top, and place it in the target container while it drys... maybe some greese on the containter walls would hlep to get it out as well, but yes... whatever's touching it when it sets is pretty much there for life.

If you had to replace the cable for some reason, it wouldn't take much to drill it out (the old cable is toast anyway) and re-pott the new cable. Probably not nessesary for most glad-cable set ups... but if you're doing some really deep dives or doubt the watertightness of your current setup this is one way to get some additional safety margin for those expensive ballasts or batteries.

I was just saying I was suprised I don't see more people refer to it int he DIY section considering the pressures and waterproof requirements underwater gear frequently needs.