I am at work on a second stage for the Dacor 400/800 balanced single hose regulator. Herman did this already, but I am trying a different approach. My idea is to make a self contained second stage, like some of the single hose regs of the past that had an adjustable volcano orifice inside the second stage body, rather than installed in the first stage. I am halfway there. I will probably complete the second stage tomorrow, and will then start to examine the real problem, which is drilling and tapping the first stage body for the new second stage, and then boring a tap into the LP air chamber.
The first stage body does not have a lot of meat for drilling into. My second stage will have to be stepped down in diameter as it penetrates in order to get the depth necessary w/o breaking out of the casting. I think I got it figured. The real problem will be tapping the LP chamber. One step at a time, eh?
This is giving me more ideas for a Dacor DH replacement second stage and lever system that could improve their performance. If I ever get to it.
That is an option I have considered. It would simplify the first stage machine work if the second stage is sealed with an o-ring and held in place with screws like the Dacor DH second stages. This would be a good option for the Dacor 400 mod, but it does make the second stage body more complicated to make, since some kind of ears or retaining scheme would need to be figured out.
My current design is a two part second stage made from a modified single hose second stage that has an adjustable hard seat inside the body. It is threaded and screws into the barrel of the lower part. I'm making a new bonnet for it, which is much like the Titan II second stage I've made. This one will use the narrower single hose seat carrier or a cut down USD.
I'm doing something partway in between, by threading a very short section of the first and second stage bodies just enough to hold the second stage in place. The rest would be sealed with an o-ring.
Here's a pic of the two parts of the unfinished second stage body, adjustable seat, and a modified seat carrier. The lower body is too long and too fat on the smooth area so will be cut down and made narrower. The hole in the first stage will be stepped down as far as possible to avoid breaking out of the body. I'll also add an o-ring groove or two, since the second stage will probably leak around the threads.
The body will not screw in the first stage all the way to the top of the threads. The Dacor body doesn't fit into the top can as far as a Titan or Trieste, and the lower second stage body will need to protrude from the surface of the first stage by about 1/4". When the upper part of the second stage is screwed on, it should protrude about 1/2" to 5/8".
Lots of hoops to jump through. I am not positive I can get the new second stage to fit the Dacor first stage. The first stage body tapers pretty severely, which limits the depth of the hole that can be drilled straight down. Herman broke through his first Dacor body when he drilled it for a seat. I hope to avoid doing this, but I have a couple extra bodies JIC.
The key will be getting the lower part of the second stage narrow and short enough to avoid coming through the side with the drill bit. The top part of the second stage body is threaded 5/8 x 24, but will only need about a 1/4" deep hole. There's room for that. The smooth section with the adjustable seat needs another 1/4 to 3/8", making the overall depth 1/2" to 5/8" deep, but the deeper cut will be narrower at 15/32".
Interesting work, keep us posted. I think I still have the body I drilled through. I sawed it in half so I could measure the space I had to work with. I also have several 400/800s if you need another one....I bought spares too. A big issue I had to overcome was how to get a venturi to work since the second stage had to be at a place that was not near the supply horn. The req will work without one but it will not breath very well without it. That is why I made the elongated one that exited the air into the horn, which worked too good and I had to reduce the flow some to keep it stable. I'm sure there are other ways to accomplish it, it will be interesting to see what you come up with.
Thanks, Herman. Not sure of success here. I could use some advice about tapping into the IP supply groove.
I've had good results with the Titan II seconds I made and venturi positions that needed custom drilling in order to direct them at the intake horn. Even with angles less than directly pointed down the hole I could get too strong venturi action.
The problem with the Dacor is the only place to put the second stage is at the "bottom/6 o'clock " position while the supply horn is at about 2 o'clock so you need to some way to get the air directed at the supply horn. No real way to do that by location of the second stage like you can do on the Titan and USD products so you have to "plumb" it to the horn somehow. The venturi on the Titan conversion is fairly easy to adjust (not so much to get it right)by adding vent holes in the second stage to bypass some of the air flow into the reg body. It just occured to me that adding the VDH DSV to the hose loop would help since it is designed to work with aggressive venturi's. The one on the AK can be setup to be very aggressive but is tamed quite a bit using it.
As for drilling the air passages, as I recall it was fairly easy, just drill a hole at an XX degree angle from the under side of the HP diaphragm....the exact angle I don't recall. I am away now but I will dig up the cutaway of the reg and get you more info when I get home.
Okay, I'm going to resurrect a very old idea from USA's DX Overpressure Breathing regulator; how about using the "hose-within-a-hose" concept to move the air down the intake tube and all the way to the mouthpiece? Use a small hose routed down the intake to the mouthpiece, mounted to the DSV mouthpiece. The inhalation non-return wold need to be drilled out to accept a hose, which would terminate at the exhalation non-return. A cutout mimicking the exact size of a Scubapro 109 cutout could be uned to direct the air to the diver's mouth. The DSV's rotation would not affect the air flow, however.
I have one of the few working DX Overpressure Breathing regulators, and it performs magnificently. It is the quietest regulator I've got, and I have SCBA hoses on it, which are longer than normal hoses, which facilitates a lower position on my back.
Fred Roberts, in his explanation of the USD Mistral regulator's Venturi orifice, went back to the DX Overpressure Breathing regulator and stated that the Mistral orifice has none of the drawbacks of the DX Overpressure Breathing regulator "gushing air, objectionable velocity into the mouth) and "approaches" the flow rates and performance of the DX Overpressure Breathing regulator. I have thought for years that a two-stage regulator with the "hose-within-a-hose" concept would out-perform any two-hose regulator now in existence.
Thanks for the suggestion, John! I had a complete working DX OverPressure a while back. The outer hoses were perfect, as was the inner one, and the duckbill too. The rubber they used for these was of far better quality than the rest of the USD stuff I've seen. Oddly, the Spiro Mistral had similar, if not identical in quality, hoses and db (not h-in-h).
The problem with the concept is the intake non-return and mouthpiece. These would be pretty hard to make, and unnecessarily complicated, IMO. If necessary, a Mistral/GL type nozzle would be the way to go, I think. I've had pretty good results with aiming the jet at the intake, although the Dacor mod may result in an inefficient venturi because of the distance.
However, keep those ideas coming! I like the input and appreciate the collaborative nature of this site!
I'm making progress, but have decided to rethink the second stage. After doing some measuring, it appears that the Dacor body is only lower in the can by 1/8". This may necessitate a hard seat in the first stage body rather than carried in the second stage like my prototype above. I also ran into tolerance difficulties on my prototype when the inside and outside threads got too close.
I also started thinking about how to just use an HPR. I've already made second stages, and don't feel the need to make everything from whole cloth! But, jets will need to be reconfigured, and such.
I want to use an o-ring sealed hard seat that presses into a bore, not threaded, so something has to keep it in place. Because air pressure will try to blow it out of the hole, I'm thinking the second stage body can press it down and retain it. Adjustments could be made with shims if the second stage needs to be backed out. This is to simplify machining, but it might create more problems. I think I'm going to go down Herman's path and make a mock-up to see if it is all reasonable.
I cut the first stage cover to make a retainer ring, calculated the placement of the second stage hole, and made the pilot hole. Now I need to make a proper jig to hold the first stage for all the machine work.....
What I have so far,
The extra flange on the retainer ring might be cut, added to and formed into an air director? It's a thought.
Only create something like an S-curve in the nozzle so that it will be aimed down the intake-horn?!?!?!?
EDIT: This would necessitate your needing to put this piece on before the HP-adjusting assembly because the nozzle would get in the way
I think a nozzle like the GL or Mistral would work, but might take a lot of tuning to control the venturi. I will simply redirect the jets toward the intake horn for the first version. As you know, I like a few revs, as evidenced by the Misuba rev4!
I spent the morning making a drilling jig. I got the port pilot hole drilled down to the max depth and bored the IP channel tap to the new port. Whew. I was a bit nervous and afraid of that one. Did 'er.
You see the new port pilot on the face of the first stage and the hole in the IP chamber just below the threads inside.