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Post by vance on Nov 5, 2021 15:23:12 GMT -8
"That's assuming there is enough metal there to safely remove without compromising the soft seating material."
That's a good question... The Healthways spring shelf can be cut a fair amount w/o interfering with the seat thickness. The Mistral is different, b/c the brass body is drilled down to the bottom, unlike the HW seat. As Bill says, taking away too much (or any?) might compromise the nylon/whatever insert.
Well, if you have to sacrifice one, prolly should do it on a bad one first? I'll be interested to hear how much you can get away with.
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Post by vance on Nov 5, 2021 15:32:04 GMT -8
You might try that to soften it a bit, which won't affect the end product. I began with a 3 or 4" piece of tubing so I could clamp 1" of an end firmly in my vise to the point of flattening that part out quite a bit so it wouldn't turn as I ran the tap in the open end. Then cut the threaded end of tube off to desired length. I couldn't get the die to start, even after turning the end down a bit. I was doing this on the lathe with a die holder chucked up in the tailpost. I'll try annealing and then thinning the very end a bit more, just to get the die started. If that fails, I'll try y our idea of flattening the end then I'll put it in the drill press vise. Maybe by using the drill press, I can get some serious pressure on it.
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Post by antique diver on Nov 5, 2021 19:43:24 GMT -8
I couldn't get the die to start, even after turning the end down a bit. I was doing this on the lathe with a die holder chucked up in the tailpost. I'll try annealing and then thinning the very end a bit more, just to get the die started. If that fails, I'll try y our idea of flattening the end then I'll put it in the drill press vise. Maybe by using the drill press, I can get some serious pressure on it. I'm confused... I thought you were trying to tap a female thread into SS tubing, then you mentioned a die like you are cutting a male thread. You must be talking about a different piece than I thought - maybe a HW reg part?
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Post by vance on Nov 5, 2021 20:00:49 GMT -8
No, I have been able to tap into the end of the 1/4" stainless tubing. I want to cut threads on the outside (1/4"x 20) to use a nut over the secondary holes like you did on your Mistral nozzle. It is for a Healthways regulator. I'm trying to recreate the GL type venturi on a Scuba or Deluxe valve.
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Post by antique diver on Nov 6, 2021 4:54:41 GMT -8
No, I have been able to tap into the end of the 1/4" stainless tubing. I want to cut threads on the outside (1/4"x 20) to use a nut over the secondary holes like you did on your Mistral nozzle. It is for a Healthways regulator. I'm trying to recreate the GL type venturi on a Scuba or Deluxe valve. If I didn't know better I would think you forgot to put on your reading glasses, and used the wrong side of the die
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Post by vance on Nov 6, 2021 7:53:06 GMT -8
That is something I might do. If it's possible to assemble something upside down and/or backwards, I'll do it. If it's possible to do it both upside down and backwards, I'll do that, but first I'll do one, then the other. But, I used the correct side of the die. The stuff is just hella hard. Back to the topic! I measured a set of fine and coarse screens (like came in DivAirs) thinking the stack would be thinner than a sintered filter. 2 fine and a coarse screen measure about .038". My thinnest sintered filter is .062", but the normal filter is about .082". Using the screens will gain about .040"of space to slacken the spring. That might do something.
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Post by antique diver on Nov 6, 2021 9:00:33 GMT -8
Thanks... I'll gladly try that!
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Post by SeaRat on Nov 6, 2021 9:05:24 GMT -8
I am curious as to why the Mistral was chosen for "improvement"? Supercharging the Mistral may be a falicious concept, as it already is, and has been since the beginning, one of the best-breathing double hose regulators ever developed. Here is a chart from the U.S. Navy Experimental Diving Unit a long time ago which demonstrates the Mistral's performance on inhalation: USD Mistral (new cover) by John Ratliff, on Flickr Note that this is better than the Aquamaster and Royal Aquamester, especially at depth. Here is a dive I made using my Mistral on June 15, 2016 titled "Getting the Lead Out," and it was in very high current where the Mistral performed extremely well. John
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Post by antique diver on Nov 6, 2021 14:16:57 GMT -8
Thanks for taking an interest, and also the chart and video.
The funny thing about the chart is that makes it hard to compare to my experience since there is no mention of air supply pressure, and there is no mention of diver position. Variations of those will contribute greatly to the recorded results. Also I am unable to accurately measure my breathing rate, but is likely significantly lower than the 2 liters per cycle specified on chart. At my slow moving easy-sipping rate during my test dive there was no apparent venturi boost. When I did briefly breathe a little more heavily I can confirm that the venturi was doing its job quite nicely. Diving in a current or otherwise diving with more demand on the reg would most certainly be easier breathing for me.
Just for comparison my cracking effort (slow easy starting breath) on the bench was about -1.4" with 2000 psi supply. With 1000 psi supply it dropped to a nice smooth -0.5" at low breathing rate. It will go slightly positive (but well under control) at momentary high breathing rate I wish I could better estimate the consumption volumes. Of course the beginning effort is obviously increased when diving in a horizontal position, when even with a low placement of the reg there is noticeable difference in effort. I don't tend to swim inclined upward, but that would help me some too.
And then, maybe I was just having a bad day at the lake, but I never have enjoyed this reg until I was down below 1500 or less pressure remaining. I guess I just need to breathe a bit more volume to make this one be at its best.
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Post by SeaRat on Nov 6, 2021 15:38:49 GMT -8
The Rubicon Research Repository is down, and has been for a while now. That is where I found this report on the Mistral. But I tried Google Scholar, and came up with this link:
The link at the bottom of this page doesn't go anywhere, unfortunately. I only took a screen shot of this graph, but the PDF had a lot more information in it. That information is no longer easily available. It is in the Rubicon Research Repository though, if it ever comes back on-line.
Concerning your discussion above, even at low inhalation efforts, the Venturi does work. It just is not perceptible as a "gush" of air. The Healthways Scuba and Scuba Deluxe were basically without a Venturi, and you needed to continue the inhalation effort to get air throughout the breathing cycle.
John
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