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ScubaLawyer
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Re: MR12 Question

Wed Jul 22, 2020 9:37 pm

UPDATE:

Finished my first MR12 rebuild. Not exactly vintage but still early 70's retro-cool. Came out all shiny and cool looking. I like shiny.

IP locked up instantly at 130 psi and cracking pressure was .9" to 1" ish so all good. Breathes amazingly. Thought I'd share.

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"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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Greg Barlow
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Re: MR12 Question

Thu Jul 23, 2020 7:32 am

Mark, that looks awesome! It literally appears to have just come off of the production line

One tuning suggestion, though, from having rebuilt more than a hundred of the Voit/Swimaster regulators. The case fault geometry (Pete Wolfinger’s term), limits the minimum cracking effort to 1.1-1.3”. I’ve tried multiple times to run various examples at 1.0”, and they never cease to have a slight free flow in a face down position. I personally set customer’s regs at 1.3” after the seating groove has been established. My own go at 1.2”.

Two tuning options are available. You can either reduce the IP from 130 down to 125, or back off the 2nd stage lever nut 1/12 of a turn. The factory specs on the 1st stage indicated 125-130psi, so I’d recommend going that route first. Plus, it’s much easier to accomplish. Having a fixed orifice 2nd stage hose connector, you don’t have the luxury of adjusting the compression of the lever spring, except with the adjustment nut.

Again, you have one beautiful reg!

Greg
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ScubaLawyer
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Re: MR12 Question

Thu Jul 23, 2020 9:06 am

Thanks for the info Greg! I've now cycled the reg a few hundred times to get a decent seat set and reduced IP to just over 125 psi. Cracking pressure is now right at 1.2" H20. 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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Greg Barlow
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Re: MR12 Question

Thu Jul 23, 2020 9:30 am

Glad to have provided some assistance, Mark. Let us know how it performs on a dive.

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Chris
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Re: MR12 Question

Sun Jul 26, 2020 2:27 am

I really like my swimaster second stage. Its what got me into rebuilding old stuf after I realized my "practice" rebuild breathed better than the plastic oceanic I had just bought from the dive store. I always wonder why, because the swimaster looks like it has a smaller diameter diaphragm than most regs.

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antique diver
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Re: MR12 Question

Sun Jul 26, 2020 8:07 am

Chris wrote:
Sun Jul 26, 2020 2:27 am
I really like my swimaster second stage. Its what got me into rebuilding old stuf after I realized my "practice" rebuild breathed better than the plastic oceanic I had just bought from the dive store. I always wonder why, because the swimaster looks like it has a smaller diameter diaphragm than most regs.
It reminds us that diaphragm diameter isn't the only factor in performance. Better engineering in the lever geometry and flow path is also important. I love it when the older regs work so well. :D
The older I get the better I was.

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Re: MR12 Question

Fri Jul 31, 2020 2:13 am

The MR-12 III is, in my opinion, the finest breathing single hose regulator ever made. And I say that as a dyed in the wool Aqualung guy. If you tune one right it will make you look like a happy skydiver at depth.

Yours is a regular MR-12 without the vortex tube, but man is that also a fantastic regulator.
The impossible missions are the only ones which succeed. -JYC

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Re: MR12 Question

Fri Jul 31, 2020 9:41 am

Ron wrote:
Fri Jul 31, 2020 2:13 am
The MR-12 III is, in my opinion, the finest breathing single hose regulator ever made. And I say that as a dyed in the wool Aqualung guy. If you tune one right it will make you look like a happy skydiver at depth.
Thanks Ron, now there's another reg I'm gonna have to add to my arsenal.... :)
"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: MR12 Question

Fri Jul 31, 2020 1:26 pm

If you really want to do one up right get a Mares MR-12III, sticker it up like a very late Voit/AMF regulator, and add an original MR-12 second stage as an octo (like the one in your picture above.) You can dive it with a low pressure inflator, SPG, and an octo that way. That setup rivals any made right now. Maybe the Mares MR22 Abyss is better...MAYBE.

Like this guy right here:
download.jpg
Bryan sells kits for it in the store too for bonus nachos.
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Re: MR12 Question

Sun Aug 02, 2020 6:28 pm

I took my rebuilt MR12 out for a test dive today. Wow! Not sure I ever had a single hose reg breathe that well! Spent 1 hr 20 min on a single LP steel 95 tank messing around in 20 to 40 feet of water. Viz wasn't great, maybe 10' or so but still had a good time. Had two huge dolphin check me out. That is always fun. l took my GoPro since I couldn't find my fishing license. I am still learning how to use it with lights, but if I get any good sequences I will try to post them later 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: MR12 Question

Mon Aug 03, 2020 9:43 pm

Took my boat out yesterday to test out the MR12 rebuild. Visibility was lousy and I couldn't find my fishing license. Ended up taking my GoPro instead of my speargun. Hadn't taken any video in a year or so but it was kind of fun getting reacquainted with the set up.

Now, I tend to pride myself with having everything all streamlined and looking proper underwater. However, on this dive I was having trouble with my mask leaking. See if you can tell why? Note: the red thingy is my mask lanyard. I had no idea it was positioned all wonky until I got home and reviewed the video. Oh well, no one's perfect. Mark

Entire video is 1min, 23 sec.



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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Re: MR12 Question

Mon Aug 03, 2020 9:58 pm

ScubaLawyer wrote:
Mon Aug 03, 2020 9:43 pm
Took my boat out yesterday to test out the MR12 rebuild. Visibility was lousy and I couldn't find my fishing license. Ended up taking my GoPro instead of my speargun. Hadn't taken any video in a year or so but it was kind of fun getting reacquainted with the set up.

Now, I tend to pride myself with having everything all streamlined and looking proper underwater. However, on this dive I was having trouble with my mask leaking. See if you can tell why? Note: the red thingy is my mask lanyard. I had no idea it was positioned all wonky until I got home and reviewed the video. Oh well, no one's perfect. Mark


What is a mask lanyard?

You guys on the left side use some weird stuff. Your BC hose now this lanyard thing. :P
Luis

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Re: MR12 Question

Mon Aug 03, 2020 10:01 pm

luis wrote:
Mon Aug 03, 2020 9:58 pm
What is a mask lanyard?
It's a Southern California beach dive surf entry thing. It is just a strap that attaches to the mask and goes around your neck. Keeps you from losing your mask in the surf.
"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: MR12 Question

Mon Aug 03, 2020 10:05 pm

ScubaLawyer wrote:
Mon Aug 03, 2020 10:01 pm
luis wrote:
Mon Aug 03, 2020 9:58 pm
What is a mask lanyard?
It's a Southern California beach dive surf entry thing. It is just a strap that attaches to the mask and goes around your neck. Keeps you from losing your mask in the surf.

Oh that sounds like something I really want to try. :shock:

I won't even consider the modern tech diving bungee cord to hold the alternate second stage. :)

Thanks for the explanation.


ScubaLawyer wrote:
Mon Aug 03, 2020 9:43 pm
Took my boat out yesterday to test out the MR12 rebuild. Visibility was lousy and I couldn't find my fishing license. Ended up taking my GoPro instead of my speargun. Hadn't taken any video in a year or so but it was kind of fun getting reacquainted with the set up.

I guess lousy visibility is very relative. That is much better visibility that I am used to here in Maine.


Very nice video. Great color. Thank you for sharing.


Someday I may have to go diving over there and enjoy some lousy visibility. :)
Luis

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ScubaLawyer
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Re: MR12 Question

Mon Aug 03, 2020 10:11 pm

luis wrote:
Mon Aug 03, 2020 10:05 pm

Oh that sounds like something I really want to try. :shock:

I won't even consider the modern tech diving bungee cord to hold the alternate second stage. :)

Thanks for the explanation.
Sam Miller invented the mask lanyard concept back in the 1950's. Ron Merker used to make sell a lot of them at the Aquatic Center. They are on a break-away swivel so there is zero chance of hanging yourself (provided of course that the break-away portion of it actually works. :) )
"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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