LP Seat Holder Stem Nut

[2THDIVR]

Was tring to find a match for the nut on the LP seat holder. Have a few extra NOS seat holders but no nuts.
Nothing I have matches except other holder nuts.
Are they 5-40 or metric? don't have metric or a 5-40 taps to compare
Will a stainless with the nylon lock from a calypso (same size) hold or do you really need to crimp a brass one?

Thanks
Scott

[captain]

The nut is a 1/8" 40.
5-40 and 6-40 are too small. No one crimps them. You can use a regular nut and if you want put a dab of silicone sealer on top or use the nylock from the single hose.

[2THDIVR]

Captain,
I did a quick search at McMaster and had no luck finding a 1/8-40 nut.
Is this a special order item for U.S. Divers?

Thanks
Scott

[antique diver]

Was tring to find a match for the nut on the LP seat holder. Have a few extra NOS seat holders but no nuts.
Nothing I have matches except other holder nuts.
Are they 5-40 or metric? don't have metric or a 5-40 taps to compare
Will a stainless with the nylon lock from a calypso (same size) hold or do you really need to crimp a brass one?

Thanks
Scott

I sure don't recommend staking the brass nut like done from factory. Way too many times it will damage the stem threads the next time you disassemble. You may even bend the stem while staking it (I learned that the hard way ). I have had good luck with using a small dot of medium loctite or even clear fingernail polish to hold the nut from accidental turning. The nylon lock style works fine if you aren't trying to keep it close to original configuration. The thread diameter is nominally 0.125", and that is the specification that I found for #5 x 40, which works for me.

Captain, am I doing something wrong about the thread size that I haven't noticed?

[luis]

The 1/8”-40 is the same as a #5-40 threads. They are easily found in McMaster-Carr (you have to buy a box, but in brass it is not expensive) or you can get them from Bryan on this link: http://www.vintagedoublehose.com/store/ ... cts_id=316


I prefer to use a drop of color (red) nail polish on the edge from the nut to the screw threads. I use the color so I can easily see if it has been disturbed (and that I didn’t forget to lock it).

The reason I prefer nail polish is because it is very easy to remove with nail polish remover and a Q-tip.


I don’t like the nylock nut for this application because there is no easy way to hold the seat holder from rotating and that tends to cut the seat.

[Herman]

The 1/8”-40 is the same as a #5-40 threads. They are easily found in McMaster-Carr (you have to buy a box, but in brass it is not expensive) or you can get them from Bryan on this link: http://www.vintagedoublehose.com/store/ ... cts_id=316


I prefer to use a drop of color (red) nail polish on the edge from the nut to the screw threads. I use the color so I can easily see if it has been disturbed (and that I didn’t forget to lock it).
The reason I prefer nail polish is because it is very easy to remove with nail polish remover and a Q-tip.


I don’t like the nylock nut for this application because there is no easy way to hold the seat holder from rotating and that tends to cut the seat.

Ahh as admit it Luis, you like fingernail polish for the same reason I do.....I can "borrow" a bottle from the wife.

Is there a good reason not to just use a 4-40 die? I realize it's a little bit smaller diameter (roughly .015) but if the threads need to be cleaned up anyway because they were damaged, would it not make sence to cut them slightly deeper? The seats are brass so cutting them is easy and since the pitch is the same, the die should start and track in the original threads with no problem. This would also make finding nuts easier.

[antique diver]

Is there a good reason not to just use a 4-40 die? I realize it's a little bit smaller diameter (roughly .015) but if the threads need to be cleaned up anyway because they were damaged, would it not make sence to cut them slightly deeper? The seats are brass so cutting them is easy and since the pitch is the same, the die should start and track in the original threads with no problem. This would also make finding nuts easier.

I actually tried that on a USD single hose carrier (same size shaft and 5-40 original threads). It didn't work out well for me... made a real mess of the threads. Luckily I had several spares to work with, so no big loss. I think you would have to turn down the shaft to the #4 diameter before attempting this, and I would prefer to keep the larger original diameter for strength.

You would probably have better luck buying a 5-40 die online and using it to dress the original threads. The brass nuts will probably be hard to find locally, but you can order them. I found a 5-40 tap locally that I use to clean threads on the brass nuts, but no dies of that size were locally available.

Luis' advice on using the plain brass with no nylon lock is definitely to be followed on the double hose regs. The locking style will work ok on most single hose appplications.

[Bryan]

You guys are aware that I had the nut reproduced EXACTLY like the original so you did not need to open a machine shop or buy 100 nuts that kinda work and you could simply replace it without a bunch of BS....Oh and you can make mouthpiece valves out of old tire tubes and some hardware

[2THDIVR]

Thanks for all the help.
I saw that if you ordered a new holder you got a new nut. But didn't look for just the nut.
Will get a few my next order.

Thanks again
Scott

[Bryan]

http://www.vintagedoublehose.com/store/ ... cts_id=316

[luis]

I would not try to cut new threads on the seat holder to a smaller size. It is not that strong to start with.

You could get a 5-40 die (McMaster-Carr has two types) to clean and chase the threads, but for the price of a die you can buy a new seat holder (with nut) from Bryan.

New seat holder:
http://www.vintagedoublehose.com/store/ ... cts_id=365


The new seat holders that Bryan makes come with the full length threaded rod (like the originals, they are excellent reproductions). Many were cut short after installation.

With the full length threaded rod it would be possible to add a back-up nut to lock the other nut. For a while, I have been thinking about try that, but the nail polish works so well that I haven’t gotten around to trying that… it is in my to-do list of things to play with.

If anyone wants to try this, just be careful holding the lower nut wile tightening the top nut or the adjustment will be disturbed when locking the two nuts together.


For the single hose I do use the original nylock nuts, but I also have the special tool with the little screw driver (to engage the slot in the seat holder) inside the nut driver.
http://www.scubatools.com/p-518-aqua-lu ... -tool.aspx


Added:
As Bryan mentioned, his reproduction nuts are identical to the originals. The McMaster –Carr ones would work but the dimensions are not the same. You are also supporting this web-site when buying Bryan’s and the prices are very good. For the price of a box of nuts, you can buy several of Bryan’s reproduction ones… sure you get 100 in a box, but even I don’t need 99 spares.