|
Post by Fibonacci on Oct 5, 2023 13:49:13 GMT -8
Continuing my Nemrod Snark DH reproduction parts, I'm now looking at the LP seats... These are co-moulded around a metal shaft and X shaped stabiliser ribs, and I need to understand what this substructure looks like to create accurate RFQ drawings for the metal and co-moulded rubber parts. Food grade silicone rubber should last longer than the originals. However all of mine are still in serviceable condition and I don't want to cut one up! Anyone got a trashed one they can either send to me or remove the rubber from and accurately measure please? My 'guesstimates' below: Snark LP Seat ASSY 2 by fibonacci101, on Flickr Snark LP Seat ASSY by fibonacci101, on Flickr Snark LP Seat supports by fibonacci101, on Flickr
|
|
|
Post by spirou on Oct 5, 2023 20:35:03 GMT -8
Do you think š¤ possible to produce LP at acceptable price š
Fred
|
|
|
Post by Fibonacci on Oct 5, 2023 21:20:17 GMT -8
Hey Fred All depends on expected volume! Unlike the Nemrod LP adaptor produced by CNC machining, the LP seats need CNC machining of the metal parts, sub-assembly, nickel plating, then tooling made for the rubber part. The operator places each sub-assembly in the mould per tool cycle and the rubber injected around it.
|
|
|
Post by vance on Oct 6, 2023 7:16:46 GMT -8
Just to make sure this information is mentioned in this thread, this style LP poppet is found in late model Silvers with the HP port. I'm not sure when the change was made and may have been done in previous models.
The late poppet is substantially different than the multi-piece early poppet, and is not generally serviceable. The internal cover/guide is also different.
Graeme, are you looking into making the older style LP soft seat pucks as well?
|
|
|
Post by SeaRat on Oct 6, 2023 7:45:34 GMT -8
|
|
|
Post by Fibonacci on Oct 6, 2023 17:19:28 GMT -8
Just to make sure this information is mentioned in this thread, this style LP poppet is found in late model Silvers with the HP port. I'm not sure when the change was made and may have been done in previous models. The late poppet is substantially different than the multi-piece early poppet, and is not generally serviceable. The internal cover/guide is also different. Graeme, are you looking into making the older style LP soft seat pucks as well? By chance all of my Snarks are late model ones, so I donāt have one to copy. Any chance you could post a pic please? Could be that there are still some numbers of NOS late model LP seats around (I saw some on Scuba Museum briefly) so maybe the focus should start on the earlier version?
|
|
|
Post by vance on Oct 7, 2023 9:21:10 GMT -8
Check the thread āSnark III rebuild (again)ā. I am not at home this w/e and will post photos of the OEM old style poppet when I return.
That thread shows the poppet I just made out of a puck cup cut from a USD poppet, but it is pretty much the same as the Nemrod part. A standard puck with a hole punched in the middle can be used to replace the worn out Snark puck. I have never had a Snark poppet that didnāt seat, though.
I made the poppet to replace the missing new style poppet in a regulator I bought. I had to enlarge the hole of the little internal guide/cover for the bigger stem. Replacing the new style poppet with the old style is a good mod, since it makes the poppet serviceable.
|
|
|
Post by vance on Oct 7, 2023 10:01:03 GMT -8
I went through that thread, and saw there is a photo of the old style poppet showing the 3 parts. Iāll post more views of it for clarity.
|
|
|
Post by vance on Oct 8, 2023 15:34:21 GMT -8
I think the molded shape of the OEM Snark seat is like what happens to a flat HP diaphragm after it's pressurized. It takes on this kind of appearance.
|
|
|
Post by vance on Oct 8, 2023 15:41:16 GMT -8
Question is: is the soft seat a cast in part, or a puck. It kind of looks like an o'ring or something, but it isn't that. My vote is that it's a puck.
The 2500 series Dacors had a puck that looked like it might have been cast, but it turns out it was a glued-in puck. So there's precedent.....
Doesn't really matter for replacement. Dig it out and replace it with a puck, same as a USD Broxton, etc., lever.
|
|
|
Post by Fibonacci on Oct 8, 2023 16:49:00 GMT -8
I was overhauling a CIG tank valve yesterday (which incidentally takes Japanese JIS Standard o-rings) and I noticed the HP seat had a roll crimp to retain it in the carrier.
That early Snark LP Seat looks similar... and back in the day would have been a lot cheaper and easier to manufacture than a moulded-in block. Usually with insert moulding there is some tell tale flash where the rubber meets the metal.
This one looks like a puck has been placed in the carrier and a roll crimp added to retain it, a bit like a Nyloc nut?
|
|
|
Post by vance on Oct 8, 2023 18:32:58 GMT -8
I haven't looked closely at an OEM LP poppet to determine if a puck was installed and a rolled rim was done to retain it. It does look like it might have been done. It seems like over-kill since the puck is already retained by the nut and upstream air pressure.
However, the soft seat shape might be due to compression from the poppet's post flare and nut, which bulges the outer circumference of the puck, + the opposing pressure from the upstream IP which compresses the inner circumference of the seat into the volcano.
I hope that makes some sense...
|
|
|
Post by snark3 on Oct 9, 2023 13:43:28 GMT -8
I have an "old style" second stage poppet that I removed the soft seat from. It took allot of soaking in denatured alcohol and allot of picking but it came out. I was able to fit a USD puck in it. Drilling the hole in the puck without a drill press is where I had problems I think. It will hold an IP of 120, any higher and it leaks
|
|
|
Post by vance on Oct 9, 2023 15:02:46 GMT -8
Huh. The upstream air pressure pretty much seats anything I've tried. My poppet holds 150+ IP with a black USD puck and softer silicone pucks. I'm not confident the silicone will last, though.
Don't worry: I wouldn't set IP to more than 135 psig for actual use.
Skip, did the soft seat come out in one piece, or did you have to scrape it out? BTW, can you PM or email me, pls? I need a part that you might have.
|
|
|
Post by vance on Oct 9, 2023 15:32:20 GMT -8
The new style, not serviceable poppet was obviously a cost cutting measure. The old style poppet is more complex, and was costly to produce. Now that replacements are no longer readily available (if at all?), a serviceable option is pretty important to keep our regs dive-worthy.
I'm considering how to make a new/old style serviceable LP poppet. The new style has a steel pin that is much smaller in diameter than the brass stem of the old style. Therefore, the internal guide/covers have different size guide holes.
It wouldn't be much different than the new, old style poppets I made. I'm thinking a stainless steel stem of the same diameter as the new style poppet would be threaded and screwed into a brass puck cup and a lock nut. Superglue and upstream IP would keep the puck in the cup. Hopefully.
Pretty easy.
However, I don't think this is the best approach to the problem. The only reason an old style poppet isn't a drop-in replacement part for the new style regs is the cover hole. The simplest fix is to replace the poppet with the old style (or new-made) and drill out the cover hole.
|
|