MK15diver
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US Divers Mistral Repair

Fri Jan 27, 2023 11:09 pm

The orifice on my US Divers Mistral isn't sealing with a new HP seat. As I look at the orifice I see it may be slightly damaged. Can this be fixed with a small round file or not and it done for good?
Someone told me that diving a double hose reg will kill me. I had no idea these things were dangerous.

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ScubaLawyer
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Re: US Divers Mistral Repair

Fri Jan 27, 2023 11:59 pm

I have used #0000 steel wool on the orifice with some success. Just depends on the extent of the damage. I wrap it around a pencil (eraser end). Do check the HP seat as I have seen defective new ones. Good luck.
"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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antique diver
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Re: US Divers Mistral Repair

Sat Jan 28, 2023 1:25 pm

MK15diver wrote:
Fri Jan 27, 2023 11:09 pm
The orifice on my US Divers Mistral isn't sealing with a new HP seat. As I look at the orifice I see it may be slightly damaged. Can this be fixed with a small round file or not and it done for good?
I don't think a file is a good idea, as it might quickly make matter worse. Could you possibly get a good well lit photo of the orifice so we could see the degree of damage to the orifice? That could help with additional suggestions for cure before resorting to that.

Mark, I hadn't heard of using the 0000 steel wool on the orifice. Always good to learn something new!
As you also mentioned, I too have seen pretty coarsely machined new hp seats that could benefit from a careful lapping routine if they don't seat in by themselves after a few days in place.
The older I get the better I was.

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Vancetp
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Re: US Divers Mistral Repair

Sat Jan 28, 2023 8:24 pm

I don't even see how you could work on the volcano orifice with a file. Are you thinking of inserting a round file in the hole and rotating it to sharpen the bevel? I might put a fine tapered reamer into it to very cautiously and gently round out the hole. I'm not sure I'd recommend doing that unless it's obviously out of round. If there's obvious damage to the sealing surface, Mark's suggestion of fine steel wool is the only reasonable way to attempt a repair unless you're a watchmaker or a good machinist.

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Vancetp
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Re: US Divers Mistral Repair

Sat Jan 28, 2023 8:26 pm

antique diver wrote:
Sat Jan 28, 2023 1:25 pm
MK15diver wrote:
Fri Jan 27, 2023 11:09 pm
The orifice on my US Divers Mistral isn't sealing with a new HP seat. As I look at the orifice I see it may be slightly damaged. Can this be fixed with a small round file or not and it done for good?
I don't think a file is a good idea, as it might quickly make matter worse. Could you possibly get a good well lit photo of the orifice so we could see the degree of damage to the orifice? That could help with additional suggestions for cure before resorting to that.

Mark, I hadn't heard of using the 0000 steel wool on the orifice. Always good to learn something new!
As you also mentioned, I too have seen pretty coarsely machined new hp seats that could benefit from a careful lapping routine if they don't seat in by themselves after a few days in place.
I'd like to see a couple of photos, too. That would make reasonable suggestions easier to make!

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Vancetp
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Re: US Divers Mistral Repair

Sun Jan 29, 2023 9:41 pm

A totally screwed orifice in a nozzle or valve body could be remediated with a major and irreversible repair. This would involve drilling out and cutting the nozzle or valve body to accept a common o'ring sealed HP seat, like a Conshelf part. This would be a pretty cool upgrade, since you'd be able to replace the HP seat in future.

This is not something anyone will be able to do, but a competent machinist could. It's not that hard.

If anyone has some valve bodies or nozzles that are bad and would send them to me, I'd love to experiment on fixing them. You might get them back fixed, and if not, you are no worse off... Except for the shipping cost. But you'd be taking one for the team?

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captain
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Re: US Divers Mistral Repair

Wed Feb 01, 2023 12:57 pm

Vancetp wrote:
Sun Jan 29, 2023 9:41 pm
A totally screwed orifice in a nozzle or valve body could be remediated with a major and irreversible repair. This would involve drilling out and cutting the nozzle or valve body to accept a common o'ring sealed HP seat, like a Conshelf part. This would be a pretty cool upgrade, since you'd be able to replace the HP seat in future.

This is not something anyone will be able to do, but a competent machinist could. It's not that hard.

If anyone has some valve bodies or nozzles that are bad and would send them to me, I'd love to experiment on fixing them. You might get them back fixed, and if not, you are no worse off... Except for the shipping cost. But you'd be taking one for the team?
Not sure that would work if the orifice size is not the same.
Captain

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Vancetp
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Re: US Divers Mistral Repair

Wed Feb 01, 2023 1:58 pm

Herman mentioned that to me as well. A new o'ring sealed or, better yet, screwed in volcano of the correct size is easy enough to make. This is simply speculation. I haven't tried it on a nozzle, due to the lack of a suitable victim. I have made several LP seats for my project regs, however.

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rhwestfall
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Re: US Divers Mistral Repair

Sat Feb 04, 2023 10:49 am

Micromesh and a chopstick/pencil?
Bob

No Longer Awaiting my Kraken.....

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Chris
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Re: US Divers Mistral Repair

Sat Apr 01, 2023 12:50 pm

I scratched the volcano on my voit 50 thinking it was removable. On my lathe I turned out a dowel that would fit town the hole perfectly straight, glued a piece of verry fine grit sandpaper to the dowel, spun it with finger pressure just till the line faded. The volcano no longer has a sharp edge, but I lucked out and it still seals. It's my favorite reg and it cost me $20 before replacing hoses and rebuilding.

SeaHuntJerry
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Re: US Divers Mistral Repair

Sat Apr 01, 2023 10:39 pm

Great you fixed a nice Voit 50 Polaris my favorite regs!

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SurfLung
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Re: US Divers Mistral Repair

Thu Apr 06, 2023 10:15 am

MK15diver wrote:
Fri Jan 27, 2023 11:09 pm
The orifice on my US Divers Mistral isn't sealing with a new HP seat. As I look at the orifice I see it may be slightly damaged. Can this be fixed with a small round file or not and it done for good?
I agree with ScubaLawyer and Chris... Have used both methods successfully several times. I think the U.S.Divers manual has a trouble shooting section that says to use a wooden dowel with a clean flat end. I think it said to use lapping compound. I don't remember if I tried lapping compound. My first approach is to use a wooden pencil with a brand new, flat erasor and #0000 steel wool (that's 4 zeros... very fine). This has worked most of the time. Be sure to WIPE the area clean afterwards as the steel wool can leave debris that might interfere with the seal between the seat and orifice. I used a dowel with 1500 grit sand paper once or twice when the #0000 steel wool wasn't getting it.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
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