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Post by vance on Mar 2, 2021 16:30:24 GMT -8
I've started work on the Dacor DH replacement second stage. For now it is designed for R-4 and up. For the R-3, it will require two holes drilled and tapped into the body for the mounting screws. We'll get to that later.
I set up an already brutalized Dacor body that, somewhere down the road, got a few amateur LP ports cut into it.
Some of you may remember the excitement (probably only mine) when I reported that I had acquired this modded Dacor.
Safe second! BCD!
I filled a couple of the botched drillings, and salvaged a couple of the not so botched ones. It does work, but that's a different, although related, story. We'll get back to it, if this second stage mod works.
Here's the plan:
Thread the original LP bore with a 3/8" x 32 tpi tap (done), and clean the bore of threads with a 3/8" drill bit, leaving just enough threads to hold the HP seat in place against LP pressure.
Make the LP seat, threaded 3/8 x 32 tpi with an o-ring at the bottom, which screws into the bore.
Make a second stage body out of rectangular brass that attaches to the reg body with screws. Mill the lever groove, plus all kinda other stuff, etc. This part is complicated b/c there's some hoops to jump through. I'll tell you about 'em later.
I bought some brass today, and made some drawings. This mought could be a'ight.
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Post by herman on Mar 3, 2021 3:44:35 GMT -8
I think I see where you are going with this. I have an alternative that might be easier to do. Instead of threading the orifice and bore, why not use a smooth bore like the HP set in a Titan or HW Gold Label, make the orifice so it projects up some, this could then be held in place by the second stage body. You may need to increase the size of the bore to allow room for the parts and enough airflow but this could be easily done with an end mill. Think something like the inside of a single hose second stage.
The elephant in the room is still a source of diaphragms.
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Post by vance on Mar 3, 2021 12:11:05 GMT -8
Thanks for the suggestions, Herman! They are always welcome. That is pretty much what I did with my Olympic conversion. The orifice is held in place by the second stage body. The problem with doing something similar on these is there is virtually NO room to increase the bore size. It's quite small, about 3/8", and it is situated almost at the outer edge of the body. I'm worried about the 1/64" of material I'm removing by tapping and clearing the threads from the top of the bore. I'm not concerned about the body, however. It is the thinness of the HP diaphragm at the edge that worries me. The Dacor diaphragm already suffers from weakness there. Diaphragms I've replaced in these are often bulgy and ready to blow. The OEM diaphragm is cut so there is an overlap of excess material in order to strengthen that spot, but is dicey. Unlike the original, my design does not have any kind of sleeve that fits into the bore. If this doesn't work out, I'm thinking about filling the original bore and cutting a new larger one that isn't so close. How far it could be moved toward the center is limited by the HP spring retainer plate, however. The diaphragm situation is more like a Mastodon. The lack of diaphragms is THE problem with fooling around with Dacors. Hopefully, this will be resolved someday, but my interest is mostly the engineering problem of making an alternative second stage that works better than the original. It could easily outperform the very simple R-3 second stage, but might not be so easy to improve on the R-4 type, even though they aren't that effective.
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Post by herman on Mar 3, 2021 13:44:41 GMT -8
How about offsetting the hole inward, incorporating the outer edge of the existing hole into the larger hole. The hold down holes could be moved in some. You might have to mill a channel in to allow flow but that wouldn't be difficult.
This may be way off base, but how about plugging the hole- threaded plug with oring seal at top, add a threaded hole in the new plug then rotate the body around 180 deg and bore a new hole more inboard. You could use the hole you already threaded with just a little counter bore at the top.
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Post by vance on Mar 3, 2021 15:34:48 GMT -8
How about offsetting the hole inward, incorporating the outer edge of the existing hole into the larger hole. The hold down holes could be moved in some. You might have to mill a channel in to allow flow but that wouldn't be difficult. This may be way off base, but how about plugging the hole- threaded plug with oring seal at top, add a threaded hole in the new plug then rotate the body around 180 deg and bore a new hole more inboard. You could use the hole you already threaded with just a little counter bore at the top. One good thing is the box screw pattern on the body. Any one of the screw holes could sacrificed to make a new larger bore for the second stage. I think I understand your idea about plugging the original bore. It is pretty much what I suggested in my previous post, I think. A nice o-ring sealed plug drilled and tapped for a box screw would be easy enough. Cutting a new one and tapping into the IP chamber is also easy enough. If I did it this way and could get at least a 1/2", (but hopefully a 5/8") bore, I'd use a Trieste style second stage. But, I'm kind of committed to the original plan. I've done the Trieste style second stage several times, and kind of fancy branching out, design-wise.
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Post by SeaRat on Mar 3, 2021 23:21:09 GMT -8
In the 1980s, I had an R-4 that I had rebuilt from an R-3 (yes, the R-3 could be converted to an R-4 by buying the parts in the 1979s). I determined that the secondary (top) lever was shaped incorrectly, with a large “U” shape built into it. Thus built, it slid down the primary lever, thereby decreasing the leverage by decreasing the lever arm of the primary lever. So I straightened it out with a hammer (I was not very sophisticated), put it back in, and it worked better. But, the hammer left a wavy aspect to the lever, and so the air flow was uneven. I shipped it off to Dacor through their local rep, and did not hear back. I asked them why they didn’t make that lever straight? No answer after several attempts. Then, I tried to get my R-4 back. Instead, they said they had lost it, and sent me a Dacor Pacer as a replacement, which I used for a number of years. But that was my attempt to may the second stage of the R-4 to breath easier. I still think that was a good idea.
John
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Post by vance on Mar 18, 2021 13:59:46 GMT -8
How about offsetting the hole inward, incorporating the outer edge of the existing hole into the larger hole. The hold down holes could be moved in some. You might have to mill a channel in to allow flow but that wouldn't be difficult. An idea I was playing around with, but wasn't sure there'd be enough room. This will require modding the box, the spring/lever plate, and the HP diaphragm. The second stage should clear the spring retainer bulge in the plate. I made a volcano orifice for the original bore, and installed it. I fooled around with various poppets, but there just isn't enough clearance for air flow. I gave that up and went for the Trieste style second stage idea.
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Post by vance on Mar 18, 2021 14:30:25 GMT -8
This is a heavily abused C-2 body, which has been used for several other experiments. My goal is to do this mod with an R-3 rather than the later types like this one. However, I didn't want to ruin an R-3 body if it isn't going to work. If it does work, it will be the best breathing R-3 on the planet!
This one works like the Dacor Olympic conversion. A hard seat will be inserted into the bore with a plastic washer/o-ring seal at the bottom, and will be held in place by a threaded nipple. In this mod, the nipple will have to be drilled through the side to open the IP air channel for the second stage. The Oly didn't need that. Then, the second stage bonnet screws onto the nipple.
This 2 piece method is necessary for lever alignment and cracking effort adjustment. There will need to be a retaining setscrew in one of the original screw holes to keep the bonnet/lever from turning out of alignment.
Speaking of the original holes, they held the second stage in, but also were used to clamp and seal the HP diaphragm at that section of the body. Those screws will probably have to be used. Just another hoop to jump through.
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Post by vance on Mar 18, 2021 14:50:07 GMT -8
Another benefit of the Trieste style second stage mod is that it eliminates the pressure on the HP diaphragm at that very thin section on the outside perimeter. This is a very weak area that often fails.
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Post by vance on Apr 2, 2021 11:45:38 GMT -8
I spent some time on the second stage mod today, making a hard seat and cutting the IP feed channel steeper so it goes under the new seat instead of into the side. The seat is installed with special tool that fits into the slots. Sorry about the blood.
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Post by herman on Apr 3, 2021 3:45:50 GMT -8
If you ain't bleedin, you ain't workin.
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Post by vance on Apr 3, 2021 9:08:03 GMT -8
If you ain't bleedin, you ain't workin. Then, I must be working all the time!
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Post by vance on Jul 18, 2021 13:31:32 GMT -8
Did a little work on this today. I cut the top box, spring mount, and body gasket for the second stage nipple. I used an orphan R-3 bottom box, an extra R-4 type spring mount, and the poor drilled up C-2 body shown above. I need to drill and tap some holes for screws on both sides of the nipple for body gasket compression. My main concern now is the body gasket, at a couple of thin spots. The OEM setup also had a very thin area at the second stage hole, so I think I'm ok as long as there's adequate squeeze on it.
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Post by vance on Jul 19, 2021 16:53:39 GMT -8
I did a bunch more today.
I cut the 2500 series HP diaphragm for a late Dacor IP aduster, drilled and tapped the main body to install some 5-40 screws around the second stage for HP gasket squeeze, and put it all together.
I powered it up. It didn't explode, so I'm hopeful. I do have a second stage leak. This was not unexpected. The spring tension on the second stage isn't there, and my HP hard seat has been abused, and needs to be redone. I also need to revisit sealing the hard seat.
I'm going to turn some more parts. I want to use a Conshelf poppet, but I'm not yet sure it will work due to the diameter of the nipple. IP is in the ball park, I think. I got 100 psig with the leak and the gasket seems to be holding. I think I can back it off even more.
Whew!
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Post by vance on Jul 20, 2021 7:40:44 GMT -8
Here's a photo of the new screws. This is to hold the HP gasket against the thin rim of the body where the second stage bore has been enlarged. One of them will probably be used to hold the second stage body in position. I'll turn a screw with a tall cap to engage a groove. The delrin second stage body shown is for a Dacor Olympic conversion, not this one. I was trying it out for spring tension.
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