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Post by antique diver on Sept 21, 2021 7:16:34 GMT -8
After wrestling for years with improving the Trieste venturi setup, I finally resorted to making both the primary jets adjustable. With this modification, and a little trial and error on the final adjustment, I was able to get the venturi action increased to my satisfaction. Which ever jet is pointing down the hose can be left unobstructed, and the one pointing into the can is decreased to whatever fine point you like simply by turning in the setscrew. Of course you don't want to be inhaling a setscrew, so it's best to use a tiny bit of removable loctite or fingernail polish to secure it in final position. After measuring a dozen times I worked up the courage to drill into the 2nd stage to try out the idea of the adjustable orifices. Using a little precision Unimat in the drill press/milling mode I bored and tapped two holes that intersected each of the two 1/8” air orifices in the 2nd stage body. Tiny #5-40 (Correction: #4-40) SS setscrews now allow me to adjust the air flow from either orifice depending upon which one was aimed inward after positioning the body for desired spring adjustment. This has turned my Trieste into one of my favorite breathing machines!
In the final photo you can see that the setscrew is partially blocking the inward facing jet. (the outward jet is wide open)
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Post by scubalawyer on Sept 21, 2021 10:10:06 GMT -8
I am the proud owner of one of Bill's adjustable venturi's for my Trieste. It, and Bill, are awesome!
Mark
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Post by antique diver on Sept 21, 2021 11:17:42 GMT -8
I am the proud owner of one of Bill's adjustable venturi's for my Trieste. It, and Bill, are awesome! Mark
Thanks, Mark... I'm glad it is working well for you!
When I sent it to you I forgot to mention the required disclaimer: "Air flowing through this item is known by the State of California to be Addictive"   |
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Post by antique diver on Sept 30, 2021 3:25:38 GMT -8
Correction to the setscrew size that I previously said was used to adjust the airflow in my Trieste.
I used #4-40, not #5 as stated in original post about adjustable venturi. The #4 just barely fit in the location, and boring the narrow space for a larger setscrew might slightly increase the potential for error in hole placement that would damage the second stage body.
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Post by vance on Sept 30, 2021 17:33:09 GMT -8
Jealous of the Unimat. I'm looking at them, but they are going for megabucks. I've got my eye on an incomplete one, but not sure I want to spend the $$, since I'm also looking at a Craftsman 6" lathe with a mill attachment. |
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Post by vance on Sept 30, 2021 17:40:42 GMT -8
I did a bunch of work on a couple of reproduction Trieste second stage bodies today. I finished cutting slots for the lever feet and the locating screws. I also turned down and shortened some Conshelf poppets to fit. I have two Trieste/Titan IIs finished except for the second stage body plating. I'm working on a 3rd, somewhat different iteration that uses a Titan II second stage lever, re-bent into the double bend foot and shortened. Photos to follow.
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Post by teamdoug2015 on Oct 1, 2021 8:20:31 GMT -8
Looking forward to seeing the photos.
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Post by nikeajax on Oct 1, 2021 15:02:03 GMT -8
PY, check your e-mail: your labels should be done...  I did some graphic work for Phil: a Trieste-lable, super easy, and a Mistral-"Pico"-label... Way back before people had computers to do graphics and things can be exact, they had art staff that were trained to do things like typography by hand. I tried my best to font match the Mistral, but had to finally give up and just get "close enough": you can literally spend hours, if not days trying to get things perfect! JB |
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Post by vance on Oct 3, 2021 18:00:14 GMT -8
Thanks, JB! They look great.
I just got back from a biannual 3 day camping trip to the Sierras. I wasn't going to go due to exhaustion from 2 months of travel, but I couldn't resist after 12 -15 years of participation. It was great. I'm even tired-er now but it was worth it.
I'll get on the photos, and I'll work on the labels. Later...
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Post by vance on Oct 4, 2021 9:48:56 GMT -8
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Post by vance on Oct 7, 2021 8:07:04 GMT -8
Due to the direction these posts are going, which include mods to the Trieste second stage, I have moved them to this new thread that is specifically about second stage mods for the Trieste and Titan II.
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Post by vance on Oct 7, 2021 8:38:16 GMT -8
My Trieste-like second stage bodies have 1/8" primary jets positioned opposite each other, and either one or two secondary 1/16" secondary jets at 90 degrees. When mounted in Trieste boxes, the improvement in venturi is pronounced with only one secondary jet, so I decided to fill the second small secondary jet drillings with silver solder.
Two of them have been sent off for plating, so I will post photos when they are finished.
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Post by vance on Oct 7, 2021 9:00:52 GMT -8
I was hoping to come up with a less complicated method of making a conversion second stage for Titan IIs utilizing the second stage body early Titan IIs were shipped with and the Titan II second stage lever, both shown above. The body, complete with a poppet and spring, were used to plug the unused second stage. Later models have a threaded plastic plug.
The modded body has a short bit of brass silver soldered to it and machined to form the rim that positions and retains a lever. The slot is cut to align one side of the hex to the body retaining screw and washer as well as aligning the lever to the center of the box.
Because the second stage body has three jets at equal intervals, only one will align with the intake horn. This means that you are stuck with a less fine cracking effort adjustment because you have to turn in or out one full revolution. However, this will work in both stock Trieste boxes as well as FX boxes.
I have sent the body off for plating, and will provide photos when it gets back.
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Post by vance on Oct 13, 2021 11:05:06 GMT -8
I got my stickers back from Zazzle. They look perfect, except they printed it on white, not transparent.  |
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Post by crabbyjim on Oct 13, 2021 11:23:41 GMT -8
If you have any extra stickers I would be happy to buy two.
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