SpudFiles

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.

Yes, it most certinly can.

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.

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.

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

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?

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

Demon wrote: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?

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.

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.

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.

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?

Demon wrote: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

Technician1002 wrote: 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.

Coodude26 wrote:
Fix'd, unless I am missing something.

Thanks for proofreading.. good catch..