How to make barley-sugar brass tubes

[PaulRParticipant @paulr]

Posted by daveb on 02/02/2017 22:56:19:

Posted by PaulR on 02/02/2017 21:41:42:

With no care at all just tried it on a bit of (annealed) steel – so easy to twist I was surprised. But the twist is uneven: after three complete turns the bottom was more tightly turned than the top. What's the fix, reverse the rod at each turn??

Interesting, I wonder if it's work hardening. Might be worth trying the twist when it's red hot.

Dave

I'll have to untwist it first I only have a little bit of that stuff left and can't afford to waste it on experiments.

[LathejackParticipant @lathejack]

That's odd, I've never come across that happening before, I wonder if the bar isn't annealed evenly along its length.

When twisting square bar for gates and railings in the past we just used black mild steel bar, mostly 10 & 12mm, and the twisting was always done cold. It made no difference which end was held stationary and which end was driven, the pitch came out even from end to end.

Thinking back, I'm sure it was usually just two to three turns of the bar.

[pgk pgkParticipant @pgkpgk17461]

As mentioned in an earlier post.. when we use(d) orthopaedic wires then to make sure the twists were even it's important to provide tension while twisting. Whether that would help prevent uneven twisting in bar metals might be difficult to arrange and require experimentation. But if you think about what happens just when you twist string.. after x number of turns it becomes springy and tries to twist on itself again. Indeed you can use that property to keep twisting and doubling thin rope up to decent tow-rope sizes (should you so wish).

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