Help sourcing an internally threaded vulcanized hard fiber seal

[99ishvr4]

I am trying to source the washer seal in the image below. It is .41" OD x .29 ID X .067" thick. The unique thing about this washer it appears to have a thread formed into the ID. I have reached out to every vulcanized fiber / hard fiber material supplier I can find and no one can make this. Does anyone here know where I could source something like this?

 

[Prometheus21]

"It appears"?

Where did you get the washer from previously? Does it have an official spec with possible thread description? If not, could it be that the washer is just worn and torn? I have seen similar washers when they are "threaded" in during installation during tight fits. The "thread" is then created during assembly, not during the manufacturing of the washer.

And if I may ask, can't you look at it the other way: Do you really need the internal "thread"? Does it actually serve a purpose, and if so; what? No reason to source a common washer dimension just to get an internal "thread" that serves no function.

Then again I could be completely wrong.

 

[3DDave]

The previous thread was deleted.

This washer was previously described as being used as an external seal on the thread for a hand operated pneumatic valve for some shop equipment. There are plenty of suppliers for this type of washer. The internal thread is a distraction as the material is soft enough to form the thread by screwing it onto the mating fitting. The use was that the existing threads could not be sealed with any sealant and this washer was the end-stop for installing the mating fitting.

"no one can make this" usually comes with one or two reasons. Things like "We won't make this in quantities less than 10,000" or "We don't thread them."

The mating part will form the threads.

 

[Prometheus21]

3DDave

"...as the material is soft enough to form the thread by screwing it onto the mating fitting" - Thank you. I tried, unsuccessfully, to say the same thing.

Reading between the lines here I'm assuming the quantity is like a handful?

Can't the thread just be made manually by either:

1. Screw it onto the mating fitting or,
2. Use a simple fixture and a smaller drill press to make the threads yourself? With a smaller amount you can actually get away with just using a fixture and a drill tap manually to create the thread. I have done that every now and then with PTFE washers over the years for weird customer prototypes. I would assumme this is possible for fiber gaskets as well with some modifications.

 

[99ishvr4]

The washer pictured is brand new. It comes with the thread in the inner diameter from the manufacturer. I do not know the original manufacturer though. When I say it appears to be formed, I mean it appears to be formed into the material, instead of being tapped afterwards.

The material looks soft enough to be formed from threading it onto a fitting, but that it is not the case at all. The fiber is very hard and it is not possible to thread on a hard fiber washer onto the fitting without destroying the washer. If I open up the ID of the washer large enough to pass over the major diameter of the threads, it does not seal correctly.

 

[3DDave]

And, because this is an effort of inches, what is that thread and why (out an overabundance of curiosity), as asked last time, can these static threads not use thread sealant like all other static threads use to seal?

 

[99ishvr4]

The thread is 5/16-24 UNF. No thread sealant is permitted unfortunately.

 

[3DDave]

See, more questions. Why is sealant not permitted?

5/16 = 0.3125. The minor diameter of the external thread is 0.2618, so the ID is much larger than the minor diameter.

You say the ID is 0.290. This is larger than the pitch diameter of .2827.

"The fiber is very hard and it is not possible to thread on a hard fiber washer onto the fitting without destroying the washer."

Was this done by testing it and do you have photos of the failure?

If it is that hard then run a tap through it.