5/8-18UNF on mini-lathe

[Demon]

Hello all

I would like to know for a project if a co2 airtank 5/8-18 UNF thread could be machined out of a lathe?

Air pressure would'nt be going over 200 psi.

[jrrdw]

Yes, it most certinly can.

[ramses]

Most likely. If you want an adapter to connect a tank to, keep in mind that there is a mechanism similar to a propane tank or schrader that must be depressed for anything to actually flow.

Also note that inside threads are generally tricky to do without a tap. Especially if you leave something in the middle to depress the mechanism I described above.

[Demon]

Most likely. If you want an adapter to connect a tank to, keep in mind that there is a mechanism similar to a propane tank or schrader that must be depressed for anything to actually flow.

A 5/8-18 UNF is the female thread inside the CO2 tank, with its valve removed, so its a male thread that goes in.

Is 5/8-18 UNF a nominal pipe thread or is much smaller/bigger ?
If anyone knows the 5/8-18 UNF datasheet, please tell me so i can get to turn it on my mini lathe.

[Gippeto]

5/8-18UNF is not pipe thread. It's a straight cut thread.

Info on major and minor diameters can be found here;

http://www.carbidedepot.com/formulas-tap-standard.htm

[Demon]

Thanks for the link

So if i thread a rod following to the datasheet that you posted, it should fit just right in a 16 oz co2 tank without its pin valve?

[ramses]

IIRC, you will need some kind of sealing aid like an o ring.

[jrrdw]

Thanks for the link

So if i thread a rod following to the datasheet that you posted, it should fit just right in a 16 oz co2 tank without its pin valve?

Use test piece's so you can get it right. Cutting thread's with a lathe can be a bit tricky when your not making matching piece's. There are variables, (I don't know your skill level).

Have you cut threads with your lathe before?

[Demon]

Nope, i but i can make a prediction that it will take me 1-2 months to get in handy with it.

(Yes...i havent buyed it yet , but i have read a lot about it and i really want a mini-lathe for all my projects, including non air smithing (electronics and robots))

But i just need to know, and i know its not a skill level for noobs( and as i am one) i need to practice and learn.

[CS]

As said internal threading is tricky. My main occurrence with this cutting procedure is that the tool holder flexes.

So two fixes: make a more rigid tool holder (1/2" cold roll square), and the other option is to make a tap. (taps become increasingly useful, as using a single point cutter tool w/ a sufficient shank size decrease)

Now the beautiful part. Taps are externally formed threads, to make internal threads. So using the same methods to create your male thread, you can make a tap. From there reliefs need to be made, these can be milled in, roughed with a angle grinder, etc. This type of tap won't last long, but perfect for one-off, few part runs.

[Demon]

As said internal threading is tricky.

Maybe, but i dont want to make internal threads, i want to make a male thread to fit in an valveless co2 16 oz tank...

And why not buy a tap? It could be a good investement.

[Demon]

Sorry for double post

But i have just seen something interesting

Does a such tap (a female one) exists for a mini 7 x 12 lathe and 5/8 - 18 unf thread?

[Technician1002]

Sorry for double post

But i have just seen something interesting

Does a such tap (a female one) exists for a mini 7 x 12 lathe and 5/8 - 18 unf thread?

The female tap is called a die. You don't need a lathe to use one. A die handle is used.
http://www.tradeindia.com/fp158682/ROUN ... ANDLE.html

[Coodude26]

The female tap is called a die. You don't need a lathe to use one. A die handle is used.

Fix'd, unless I am missing something.

Just to clarify:
A tap: used to cut threads on the inside of a piece of metal (ie, a hole)

http://www.nmri.go.jp/eng/khirata/metal ... 01_big.jpg


A Die: used to cut threads on the outside of a piece of metal (ie, a metal rod)
http://images.toolspot.co.uk/Tap%20&%20 ... 0Set_2.jpg


Also as other people have said using a lathe is very difficult and takes a lot of experience so if you ever end up going for that approach, take it slow and know that you won't get it right on the first (or tenth) try.

[Technician1002]

Fix'd, unless I am missing something.

Thanks for proofreading.. good catch..