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Discussion of diving methods and equipment available prior to the development of BCDs beyond the horse collar. This forum is dedicated to the pre-1970 diving.
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ScubaLawyer
Master Diver
Posts: 1649
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

HW main diaphragm top plate question

Tue Sep 04, 2018 10:18 pm

Here is one of Rob's superb Healthways main diaphragm reproductions next to an original from a HW Scuba 1st gen that has a top plate. My question: is there any benefit (or detriment) to having a top plate affixed?

Image

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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Bronze06
Master Diver
Posts: 666
Joined: Tue Jul 01, 2014 5:33 am
First Name: Russell
Location: Tabuk, Saudi Arabia

Re: HW main diaphragm top plate question

Wed Sep 05, 2018 3:06 am

My personal opinion is NO! On the original diaphragms, the top plate might have been there to ensure strength and seal protection due to the materials being used, just a guess. With Rob's new silicon diaphragms I have found no evidence of seepage into the air chamber. The top rivet point can protect the seal and in some cases, I have shortened and compressed that rivet a little more at times, so as to tweak the reg for easier breathing effort as the rivet is IMO a little high, especially in the 1955 model. I've rebuilt 4 Healthways using Rob's diaphragms and they breath great.
"Where'd ya get that ol' thang, don't cha' know them thare things ill kill ya!"

Live From the Red Sea,

Russ

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ScubaLawyer
Master Diver
Posts: 1649
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

Re: HW main diaphragm top plate question

Thu Sep 06, 2018 10:01 am

Bronze06 wrote:
Wed Sep 05, 2018 3:06 am
My personal opinion is NO! On the original diaphragms, the top plate might have been there to ensure strength and seal protection due to the materials being used, just a guess. With Rob's new silicon diaphragms I have found no evidence of seepage into the air chamber. The top rivet point can protect the seal and in some cases, I have shortened and compressed that rivet a little more at times, so as to tweak the reg for easier breathing effort as the rivet is IMO a little high, especially in the 1955 model. I've rebuilt 4 Healthways using Rob's diaphragms and they breath great.
Thanks for responding Russ. I think you're right, I don't see how it would make much of a difference other than to clamp the bottom plate tighter to the diaphragm. Not sure that helps any. If I want to be authentic I guess I could drill out Rob's pop rivet, add the old upper plate and pop rivet it all together again. Sort of sounds like overkill.

I shall continue to ponder the issue over a single malt and a Monte Cristo No. 2
"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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Bronze06
Master Diver
Posts: 666
Joined: Tue Jul 01, 2014 5:33 am
First Name: Russell
Location: Tabuk, Saudi Arabia

Re: HW main diaphragm top plate question

Mon Sep 10, 2018 2:07 pm

That sounds like a great way to ponder to me.
"Where'd ya get that ol' thang, don't cha' know them thare things ill kill ya!"

Live From the Red Sea,

Russ

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