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ScubaLawyer
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Re: Question on reproduction silicone diaphragms

Wed Oct 03, 2018 9:43 am

tripplec wrote:
Wed Oct 03, 2018 9:23 am
The beads are for alighnment, then you poor the silicone in and squeeze them together? Where did you get the materials, most things like sulferless clay are unheard of in Coos Bay Oregon. When you poored the second half, did you sprinkle in something like baby powder to to keep the halves from sticking?
After a crap-ton of research I ordered the various silicones, catalysts, clay and coloring from Polytek in Easton, Pennsylvania. To keep the mold from sticking I used Polytek 2500 (a spray mold release that works with the chemical composition of the type of material I was using.)

Thanks guys for your positive comments.  I'm going to continue messing around with different shore hardnesses of silicone casting material to see what works best. This one does fit the HW reg though.
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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Re: Question on reproduction silicone diaphragms

Fri Oct 05, 2018 12:31 am

Still experimenting. Color is a little off and consistency ain't perfect yet.

Image

Color is better, and it would likely work, but still too soft and bendy in my opinion. Back to the drawing board for strengthening the tetravalent polymer chains. 8)

Image
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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couv
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Re: Question on reproduction silicone diaphragms

Fri Oct 05, 2018 4:04 pm

Well, I'm impressed. Nice job!
A sincere THANK YOU to all at VDH who make this wonderful resource available and to all the thoughtful contributors.

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Re: Question on reproduction silicone diaphragms

Sat Oct 06, 2018 12:06 pm

The diaphragm looks great! This is a major step toward making Scubas more rebuildable and usable!

What is your concern about its flexibility? Like the new silicone main diaphragms, a softer, more flexible exhaust diaphragm might just work a lot better than the old rubber covered fabric parts! Part of the problem with the originals is that they don't seal the horn all that well. Are you worried about strength, tearing, or cutting by the clamp?

Great work, Mark!!

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Re: Question on reproduction silicone diaphragms

Sat Oct 06, 2018 12:42 pm

Vancetp wrote:
Sat Oct 06, 2018 12:06 pm
Are you worried about strength, tearing, or cutting by the clamp?
Hi Phil,

That, and, for want of a better word, the silicone casting material, while it appears to seal well on the reg, is sort of "slippery. " I may be worrying for nothing but I wouldn't want the material to "push out" under the wire clamp with repeated exhalations. The solution, I think, would be a little stiffer material.  When I get what I think will work I'll probably have some kind of alternate air source available just in case during field testing.

Any and all recommendations are welcome. Ask your friends, relatives and co-workers. :D

Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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Re: Question on reproduction silicone diaphragms

Sat Oct 06, 2018 2:05 pm

ScubaLawyer wrote:
Sat Oct 06, 2018 12:42 pm
Vancetp wrote:
Sat Oct 06, 2018 12:06 pm
Are you worried about strength, tearing, or cutting by the clamp?
Hi Phil,

That, and, for want of a better word, the silicone casting material, while it appears to seal well on the reg, is sort of "slippery. " I may be worrying for nothing but I wouldn't want the material to "push out" under the wire clamp with repeated exhalations. The solution, I think, would be a little stiffer material.  When I get what I think will work I'll probably have some kind of alternate air source available just in case during field testing.

Any and all recommendations are welcome. Ask your friends, relatives and co-workers. :D

Mark
I can understand your concern about it slipping out. You may want to try gluing it before you clamp it. Any bonding will never be fully permanent against that silicone, so you will be able to replace it.
Luis

Buceador con escafandra autónoma clásica.

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Re: Question on reproduction silicone diaphragms

Sat Oct 06, 2018 2:49 pm

Thanks for the input Luis. I definitely plan to glue the final diaphragm in place in addition to clamping it. I believe the consistency of the casting material I am currently using is adequately strong and tear resistant. It seals very well on the inside edge of the exhaust horn - better than the original. I am afraid the wire clamp may cut into the material. Not much practical use if you have to replace the exhaust diaphragm after every day of diving. Good thing I am having fun messing around with it. If I wasn't the frustration level would have done me in long ago.

Again, if anyone knows anybody that has done something similar or has any expertise in this area I am all ears. Don't mind a collaborative effort at all. Somebody out there must be dealing with the same HW Scuba exhaust diaphragm issue. Haven't heard back from Jeff Healey yet on his experiments. I am confident of success! :D
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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Re: Question on reproduction silicone diaphragms

Sun Oct 07, 2018 9:34 am

Mark, I've been watching this thread with great interest as I own a Healthways Scuba. Mine seals and works, but I had to patch it to get it that way. If you make a few extra's when you feel you have it right, I'd be interested. Yes, I'll sign a release. As far as I'm concerned color doesn't matter as it will be covered up anyway. Bare in mind that 50 - 60 years ago, everything was softer and bendyier. Lol.
Keep at it. Good luck on the project.

Jim

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Re: Question on reproduction silicone diaphragms

Sun Oct 07, 2018 10:51 am

Jim,

Thanks for the words of encouragement. I attached one of my creations with the wire holder yesterday. Let's just say the material is too soft to hold up to that tight of clamping. I have ordered a denser casting gel along with a catalytic hardner to be able to fine tune the results. I will report back as the project develops further. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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Re: Question on reproduction silicone diaphragms

Sun Oct 07, 2018 11:58 am

You might try rubber cement, then tie it on with multiple wraps synthetic thread, like polyester instead of cotton. Worked well on early regulator exhaling valves. You can control how snug that goes and maybe minimize damage to the soft silicone.


Thanks for the experimentation you are posting. I'm watching and learning from you! Maybe I can talk you into building me one for a future project, and like Swimjim, I might be willing to sign one of those 14 page legal releases... if I can figure out what it says! :?
The older I get the better I was.

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Re: Question on reproduction silicone diaphragms

Sun Oct 07, 2018 1:12 pm

Thanks for the suggestions Bill. Of course I would require any release be signed in blood so that DNA analysis can prove authenticity. :D Paranoid? Nah, not me.... :shock:

Ultimately,  when (or if?) I get the right silicone compound for casting I would like to find a NOS exhaust diaphragm in perfect condition so I can recast the mold. The mold silicone is so sensitive it picks up every little imperfection. My original has a hole in one end that I patched but one can still see the imperfections in the mold and in the castings. I'm not there yet but if anyone has a NOS original I'd love to borrow it for a final mold. The process is non-destructive and I'd give it back. No rush, just thought I'd throw the idea out there. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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Re: Question on reproduction silicone diaphragms

Sun Oct 07, 2018 5:12 pm

ScubaLawyer wrote:
Sun Oct 07, 2018 1:12 pm
Thanks for the suggestions Bill. Of course I would require any release be signed in blood so that DNA analysis can prove authenticity. :D Paranoid? Nah, not me.... :shock:
No problem Mark. I keep a pint in the refrigerator just for Lawyers.
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Re: Question on reproduction silicone diaphragms

Sun Oct 07, 2018 5:56 pm

ScubaLawyer wrote:
Sun Oct 07, 2018 1:12 pm
Thanks for the suggestions Bill. Of course I would require any release be signed in blood so that DNA analysis can prove authenticity. :D Paranoid? Nah, not me.... :shock:

Ultimately,  when (or if?) I get the right silicone compound for casting I would like to find a NOS exhaust diaphragm in perfect condition so I can recast the mold. The mold silicone is so sensitive it picks up every little imperfection. My original has a hole in one end that I patched but one can still see the imperfections in the mold and in the castings. I'm not there yet but if anyone has a NOS original I'd love to borrow it for a final mold. The process is non-destructive and I'd give it back. No rush, just thought I'd throw the idea out there. Mark
I will look for a good one to send down to you. I know I have several with good flanges, but I think they're kind of crinkly on the flat top. I also need to see if I can find one that's not glued in.....
Phil

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Re: Question on reproduction silicone diaphragms

Sun Oct 07, 2018 6:19 pm

Thanks Phil, no rush at all.

The lack of cement is important because it is next to impossible to get it all off and any residual will f-up the mold.
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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Re: Question on reproduction silicone diaphragms

Sun Oct 07, 2018 6:48 pm

I just checked two of them. They're glued in so well I'm afraid to try to get them off. I have one more to check, but I'm sure it's glued in as well.

Can you trim/sculpt one of your new diaphragms to correct the imperfection and make a new mold? Or does the bump even matter?

As I said, the diaphragms I put on with RTV are really glued in. I don't think you'd even need a clamp with them. Of course, they are a different material and might glue better than silicone. Does RTV hold well on this silicone compound? Just slipping the wire clamp over the flange and gently tightening it down will keep my neoprene diaphragms in place for sure.

The thread method might be good, if you have clever enough hands to do that wrap. Have you experimented with an o-ring keeper?

I don't know how much/far the diaphragm flexes when you exhale. Is there really much inward pressure on it? I'd be surprised if it was anywhere near enough to force the diaphragm flange out of the clamp. I could be very wrong about that. Does anyone with some expertise know? Luis?

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