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Post by antique diver on Nov 27, 2021 4:32:21 GMT -8
I knew an older fellow that had personally converted surplus aviation Oxygen regulators for underwater use in the early 1950's, and actually took them cave diving :shock: He and his small group of adventurous cave diving pioneers were almost certainly the first to use diving "Lungs" to begin underwater exploration in Phantom Lake Cave. When we began our exploration and biological collections project for the Bureau of Reclamation there in 1995 he got wind of it and wrote to me telling of his early experiences there. We met up at Phantom a few months later, and he showed us some of his interesting collection of old diving gear they used there in the 50's, much of it homemade, and some was pretty well done. John entertained us for hours with his interesting tales of early cave diving. Here's a exact quote from John Coffee’s letter to me in 1996: "Myself,…John Mason and… Al Hull did preliminary non photographic dives into the system beginning in 1952 with dive gear so primitive that the two hose Aqualung regulator is Star Trek quality. We used 1800 psi aluminum Air Force high altitude demand regulators converted to two hose underwater breathing gear and ran them at 3000 psi, often with disastrous results such as the first stage suddenly disappearing with a loud “bang”.It's really a wonder that they survived given the complexity of the cave, the questionable quality of their gear and the general lack of knowledge of cave diving available at the time! (John is gone now, but it wasn't diving that got him... just old age)
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Post by SeaRat on Nov 27, 2021 9:03:53 GMT -8
Bill,
I think it would be important to have those letters written out and posted here, perhaps in a different thread. It sounds like there was some significant history in those letters, and we should preserve it.
John
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Post by antique diver on Nov 27, 2021 11:47:55 GMT -8
Bill, I think it would be important to have those letters written out and posted here, perhaps in a different thread. It sounds like there was some significant history in those letters, and we should preserve it. John I agree. I only have the one letter, but Coffee also sent some photos which sadly are pretty poor, but better than nothing. I’ll see what I can come up with. Hopefully I can find some photos I took of his old gear.
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Post by nikeajax on Nov 27, 2021 16:09:24 GMT -8
I agree. I only have the one letter, but Coffee also sent some photos which sadly are pretty poor, but better than nothing. I’ll see what I can come up with. Hopefully I can find some photos I took of his old gear. I'm a professional graphic artist and I do very high quality photo restorations: let me know if you'd like the doctored up JB
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Post by antique diver on Nov 27, 2021 16:33:35 GMT -8
I agree. I only have the one letter, but Coffee also sent some photos which sadly are pretty poor, but better than nothing. I’ll see what I can come up with. Hopefully I can find some photos I took of his old gear. I'm a professional graphic artist and I do very high quality photo restorations: let me know if you'd like the doctored up JB Sounds good. I'll need to find some, and it may take a while. We moved in 2016, and lots of photos are "somewhere". I will be looking. Thanks JB.
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Post by vance on Nov 27, 2021 16:38:31 GMT -8
You're making me want to do more work on the diluter. I had sorta convinced myself that it's not worth it. But Bill keeps throwing out tidbits of hope.
I'm thinking of a new lever that is more like modern ones. This came about when I got another diluter. I broke the threaded stem off the lever during disassembly. I figured it's junk now, but it got me thinking about how to fix it. Maybe a different lever that uses contact points rather than a stem and nut that goes through the diaphragm?
I'm not doing much these days, so maybe I'll take out the stainless steel sheet metal, the hacksaw, and fire up the torch....?
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Post by antique diver on Nov 27, 2021 17:47:24 GMT -8
You're making me want to do more work on the diluter. I had sorta convinced myself that it's not worth it. But Bill keeps throwing out tidbits of hope. I'm thinking of a new lever that is more like modern ones. This came about when I got another diluter. I broke the threaded stem off the lever during disassembly. I figured it's junk now, but it got me thinking about how to fix it. Maybe a different lever that uses contact points rather than a stem and nut that goes through the diaphragm? I'm not doing much these days, so maybe I'll take out the stainless steel sheet metal, the hacksaw, and fire up the torch....? GO PHIL!
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Post by vance on Nov 29, 2021 10:41:57 GMT -8
I thought everyone following this might be interested in the differences in the two diluters I have. The one I have done work on already is just like Bill's. The second one is a bit different, and has an intriguing feature. The diaphragm on this one is mounted to a metal ring which attaches to the body with long screws. A bummer about this is that it's a potential point of water entry. Some kind of sealer would be needed. But, the diaphragm attachment to the body might be easier to deal with, esp if the diaphragm was simply made directly on the ring. Here's what I did to the second one. This got me thinking about repairs and a different diaphragm interface.
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Post by SeaRat on Nov 29, 2021 11:23:47 GMT -8
Are we looking at a tilt valve second stage, or an upstream push valve? From the photo, it looks like it could be either.
John
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Post by vance on Nov 29, 2021 11:59:50 GMT -8
It is not a tilt valve, but a push valve.
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Post by vance on Nov 29, 2021 14:47:57 GMT -8
Is there any potential for the LP output from the back side of the second stage (with the 1/4" pipe plug on the outside of the regulator body)? You can see the square end of the plug in the photo above showing the broken second stage lever.
The center outlet is where it seems obvious to tap in for intake, but if it were plugged and air was provided to the mouthpiece via the pipe plug side? It would be convenient for jetting.... Not sure how position would affect it, like the exhaust placement does.
Crazy, right?
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Post by vance on Nov 29, 2021 15:06:25 GMT -8
I took the original mixer parts out of the second diluter. It is also different. The center opening for the second stage is smaller. I think I like it better, b/c a smaller diameter tube can be easily inserted into it and held in place by the casting that used to support the mixer (Done, and photos to follow). This simplifies the machine work, and reduces the output tube diameter, which will increase velocity (venturi), and hopefully, efficiency.
I started to implement the idea on the first diluter, but it was more complicated and still hasn't been finished...
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Post by vance on Nov 29, 2021 15:28:39 GMT -8
BTW, we have progressed well beyond the scope of the original Popular Science Magazine conversion here. We know a lot more than the OGs who braved the deep with these conversions. The mods we are proposing here weren't known back then.
I am interested in this as a mental and engineering exercise. My goal, and I'm sure Bill T's is as well, is to make the diluter conversion into something more than a marginally divable regulator. I bought the second diluter b/c I wanted to faithfully follow the PSM instructions. I wanted another one b/c I wanted to continue converting my first one using the experience I've gotten over the years and the contributions of others who know what they are talking about.
Unfortunately, my second diluter isn't the early model that they used back in the day, so I couldn't make an exact replica. I still want to make a replica, and maybe someday I will.
I definitely won't dive it unless it's a pool test.
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Post by antique diver on Nov 30, 2021 11:31:24 GMT -8
Evolution of the Bendix Diving Lung diaphragm 1. Crumbling remains of the original Bendix from about 1942; (wet breathing) :? 2. July 2018 version in place on Bendix. Flowable Silicone spread onto sheer nylon mesh stretched over jig/mold. Used original back up plate. Soft and stretchy It worked well only with slow easy breaths up to 30' depth. Fairly successful, as we have survived numerous dives! (Lately determined that it needs more height and a smaller interior support disc to allow more flex, stretch and demand lever travel... which led to the next versions) 3. 11/25/2021 version with new shape designed for more demand lever travel. Support disc reduced to 1.625" diameter. Same fabric sprayed with Plasti-Dip. Too stiff, no stretch... won't work. Maybe too many thin coats? Gave up on it. 4. 11/29/2021 version with same shape as #3. Constructed using same materials and method as #2. Back to using Flowable Silicone applied with finger tip. Jig/mold was modified to readily adjust for different heights, making it easy to make a variety of shapes in only a day each. Shown here still curing on the jig. Skirt will be trimmed to proper length upon curing. Hopeful that this will provide adequate air volume for heavier breathing when needed, since the demand valve will open much farther than with #2 version. Test bench experiments have been very promising. [/font]
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Post by vance on Nov 30, 2021 13:42:19 GMT -8
That looks fantastic. I'm going to have to give it a try.
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