Subject: Re: How do you swage tubing?

From: [email-masked] (Barry Workman)
Date: Tue, 7 Feb 1995 02:21:58 GMT

[email-masked] (Mike Rehmus) writes:

>In <[email-masked]> [email-masked] (James 
>Kirkpatrick) writes: 

>>
>>
>>In article <[email-masked]>, [email-masked] (Richard 
>Karlquist) writes:
>>|>
>>|>Anyone know how to "swage" aluminum tubing?  
>>|>Can it be done by the hobbyist?  I want to build
>>|>some antennas and this might be useful.  "Swaging", in case
>>|>you don't know the term, is where the last 6 to 12 inches or
>>|>so of an aluminum tube is of a reduced diameter, so it will
>>|>slip inside another piece of the same size tubing.
>>|>I was thinking maybe this is done in a lathe, but I am not
>>|>sure of the tool to use to push on the tubing.
>>
>>Just a wild-ass-guess (WAG), but maybe you could use a pincher-style
>>knurling tool, with smooth wheels in place of the knurls.  Since 6-12
>>inches is a goodly bit of length, you may want to make a stepped
>>mandrel to support the tubing, and run the mandrel between centers;
>>especially if you try to use a single-wheel knurling type arrangement
>>where you have to press sideways only, and/or if the tubing is small
>>and fragile.  If nothing else, a mandrel will help you keep things
>>straight.  Might try it without, first, just to see how it goes.
>>
>>The industry guys probably use giant presses to do this.
>>
>>I have no idea what this will do to the strength of the tubing around
>>the reduction; it might work-harden and become brittle, challenging 
>your
>>tower-climbing desires.
>>
>>Sounds interesting.  Let us know what you come up with!
>>
>>Jim
>>

>The problem is that you need to support all sides of the tubing at the 
>same time or it will collapse or bend.  That is why they use swaging 
>dies with a fair amount of power behind them.  I seem to remember that 
>the muffler shops solve this problem with some kind of tool.  Go visit a 
>few and tell us what you found.

>mike

It would seem to me, the easiest thing would be to get a drawplate or
make one that suits your specifications.  Draw several inches more than
you need and discard the rest.  Aluminum, copper, and brass all draw
fairly easily.
-- 
    - Barry Workman