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Greg Barlow
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Re: MR-12 Rebuild

Tue Jul 17, 2012 11:19 am

I place the exhaust tee in hot water (tap, not boiling) for around 10 minutes. I then flex the ends of the tee toward one another. I slip one side on the flange, and then stretch the other side into position.

On a positive note, I've yet to see one come off unexpectedly.

Greg
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Drado
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Re: MR-12 Rebuild

Wed Jul 18, 2012 8:24 am

Greg Barlow wrote:I place the exhaust tee in hot water (tap, not boiling) for around 10 minutes. I then flex the ends of the tee toward one another. I slip one side on the flange, and then stretch the other side into position.

On a positive note, I've yet to see one come off unexpectedly.

Greg
Thank you sir! That trick, plus a little soap around the flange made putting the T on easy.

My MR-12 thanks you! Now to put it on my red label PHPR as a back up.
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Re: MR-12 Rebuild

Fri Aug 03, 2012 7:20 am

I just love how solidly built these regs are. I recently acquired one which was in pretty rough shape. It was covered with gunk and the front cover was actually dented in places. I managed to clean most of it up in the ultrasonic and was able to pound out most of the dents before sending it out for a re-chrome:

Before:

Image

After:

Image

Because of their fantastic compact nature, they serve as the octos on my PRAMs and on my Al40:

Image

Image
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antique diver
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Re: MR-12 Rebuild

Fri Aug 03, 2012 8:31 am

Wow, that's gotta be the worst looking "before" that I ever saw!

The refinished ones look great. They are also some of my favorites. :)
The older I get the better I was.

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gj1963
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Re: MR-12 Rebuild

Fri Aug 03, 2012 11:25 am

Great job - that looks fantastic.
-Geoff

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Re: MR-12 Rebuild

Fri Aug 03, 2012 6:56 pm

Talk about a diamond in the ROUGH! Great Job!

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Drado
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Re: MR-12 Rebuild

Wed Aug 08, 2012 9:42 pm

swimjim wrote:Talk about a diamond in the ROUGH! Great Job!
I'm so glad I got this! it kinda breathes smoother than my 156s, and considering the simplicity of the design, if I were to keep just one 2nd stage, this would be it! (vs. some conshelfs and SP156s)
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macado
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Re: MR-12 Rebuild

Mon Aug 13, 2012 10:03 am

Great thread. I just rebuilt an older MR-12 I had lying around. The same 2nd stage that Drado posted) I really like this regulator. Been using it for shore diving recently on my singles.

Extremely simple to rebuild, reminded me a lot of the Voit Triest first stage. The only thing I didn't do was replace the white teflon o-ring in the balance chamber, hope that's fine.

IP locks up very quickly and stays stable. I stuck an old Mares Axis Pro 2nd stage for a backup regulator on it. I figured it was an appropriate second stage given it's history and design similarities.

What is the deal with the 2nd stage diaphragm? The one I have seems to be perfectly fine. Is there any benefit to swapping it out for a Mares Abyss black silicone diaphragm? Haven't put it on a magnehelic but have had reg down to 60fsw and breathes good enough for me.

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Greg Barlow
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Re: MR-12 Rebuild

Tue Aug 14, 2012 5:12 pm

I don't replace the back-up ring unless there is visible damage to it. The risk of damaging the HP balance chamber's interior is too great.

Your reg likely has a silicone diaphragm if it breathes real well. Voit/Swimaster used them in the last few years of production. The previous versions were composed of a coated fabric. They became stiff with passage of time.

I just rebuilt a Trieste II for a friend. The diaphragm was in outstanding condition. Pretty rare to find one like that.

Greg
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frogman63
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Re: MR-12 Rebuild

Mon Oct 08, 2012 9:54 pm

Pretty impressive work on those MR12's. What type of tool do you recommend to remove and then reinstall the 2nd stage poppet? Thanks. Brian

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Nemrod
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Re: MR-12 Rebuild

Wed Oct 10, 2012 11:23 pm

Sometimes, you can put your fingers inside the exhaust tee and use them to help stretch the opening over the cup. Be careful not to tear it.

I have noticed in the past that there is a difference in height between the bullseye top cover and the older black face. I have since sold off my black face units because I am partial to the bulls eye MR12II with the aspirator tube, seem to breath just a ever bit better to me but it might just be wishful thinking.

On all of these simple non balanced types, I always back the orifice off during storage (while pressing the purge or lever down) to prevent it from taking a deep set.

Very nice job on the rebuild.

Nem

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Drado
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Re: MR-12 Rebuild

Thu Oct 11, 2012 7:05 am

Nemrod wrote: I have noticed in the past that there is a difference in height between the bullseye top cover and the older black face. I have since sold off my black face units because I am partial to the bulls eye MR12II with the aspirator tube, seem to breath just a ever bit better to me but it might just be wishful thinking.


Very nice job on the rebuild.

Nem
Yeah, the bullseye seems to use a lower lever height. Using the black face lever height usually gives me a slight free flow when I tighten down the box top, and yeah, the VAD really makes it breathe effortlessly :D
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Re: MR-12 Rebuild

Wed Jan 23, 2013 10:46 am

Thanks for all the good input Drado and Greg. I ended up getting everything tuned pretty well, but for me, it was a lot of trial and error. I'd remove the diaphragm on the MR-12 and adjust and then repeat the process until I was fine tuning at about 1/16th of a turn. The MR-12 II I picked up, is a little less finicky. At least, that's been my experience.

Image

I've dove the MR-12 a couple times now, and it's smooth and easy, but I'm not getting the warm fuzzy feeling that this is the best reg ever. The MR-12 II, seems to breath a little bit better.

On a sad note, I've only breathed the MR-12 II underwater very breifly. Last weekend I had plans to dive it, but was called just before the dive by my buddy, who informed me that her reg(an Atomic) was blowing bubbles out of the 1st stage somewhere and that she needed to barrow a set of regs and a drysuit hose. So, this is what she got.

Image

We were diving in the channel again to look for bottles and steamship china. The only logo I found was on this broken bit:

Image

Found a cool cork stopper elixer bottle, possible even a bitters bottle:

Image

Overall, I think the MR-12's are working well, and my buddy from the other night, says she thought it breathed well, she didn't even notice the leak in the air hose.(A Scuba Pro replacement)

Image
I do not believe in taking unnecessary risks, but a life without risk is not worth living. - Charles Lindbergh

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Re: MR-12 Rebuild

Sat Feb 23, 2013 8:28 pm

This may have been answered before but what's the deal with MR-12 and HP tanks (3400-3500psi)?

I've only since used my Voit MR-12 with LP tanks or AL80s. Would there be any issue with using HP tanks? I know the yoke itself is somewhat thin and the first stage is balanced. Safe to use with HP tanks or better to use something else?

Going on a dive trip and trying to minimize number of regulators to bring.

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Nemrod
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Re: MR-12 Rebuild

Tue Feb 26, 2013 9:20 pm

The fixed yoke first may not fit some modern valves, especially those with the inserts. It should handle 3,000 psi fine but beyond that might be a "stretch" if you follow.

Mine has no issues with 3,000 plus psi:

Image

Nem

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