# Reducing copper tubing?



## vlmarshall (Oct 9, 2009)

Have any of you reduced the ID of copper tubing by rolling it? I'd like to try to reduce some 1/8" copper tube (.062" ID) down to around .012". A coworker suggested the idea, so I tried it first at work, with a bearing mounted in a knurling tool holder. It seemed to be working, until the copper work-hardened and snapped off at the collet.
Later I tried something similar at home, forcing the copper tubing between two bearings at angles. That didn't work either, the end of the copper cone i was forming work hardened and developed radial cracks.


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## websterz (Oct 9, 2009)

You're on the right track. You are just going to have to stop at least once and anneal the tubing to counteract the work hardening. Go halfway with the reduction, stop and heat the tubing to a dull red and let it sit and cool slowly, then resume. Take your time and it'll work.


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## vlmarshall (Oct 9, 2009)

websterz  said:
			
		

> You're on the right track. You are just going to have to stop at least once and anneal the tubing to counteract the work hardening. Go halfway with the reduction, stop and heat the tubing to a dull red and let it sit and cool slowly, then resume. Take your time and it'll work.



That's what I was hoping to hear; that annealing the copper would help greatly. I'd only annealed it before working. 

I'll make a real fixture for the bearings and try again. Even milled to equal widths, the hex-nuts-in-vise system wasn't too stable. ;D

Thanks!


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## bearcar1 (Oct 9, 2009)

Looks like you are attempting to form a blast pipe cone for your exhaust, Vernon. Maybe not. I have always considered using a plate that has had the taper milled into it and after annealing, force the pipe end down into the opening, thus supporting the entire radial surface of the tube. I've never tried that but your method of doing so looks interesting. I'll be watching with interest.

BC1
Jim


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## vlmarshall (Oct 9, 2009)

bearcar1  said:
			
		

> Looks like you are attempting to form a blast pipe cone for your exhaust, Vernon. Maybe not. I have always considered using a plate that has had the taper milled into it and after annealing, force the pipe end down into the opening, thus supporting the entire radial surface of the tube. I've never tried that but your method of doing so looks interesting. I'll be watching with interest.
> 
> BC1
> Jim


Nice idea, kinda like a wire-drawing plate.
However, I'm not making anything so interesting as a blast-pipe cone. It's just an idea for a quick-and-easy fuel jet for the butane burners in my Crackers, without drilling, or poking tiny holes in foil.


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## ghart3 (Oct 9, 2009)

Drawing out by hammering or rolling between two adjustable rolls with Vees cut in them would work.  Drawing out by squeezing or hammering requires work to be square and to be stretched in length.

Just tried a quick and dirty method, cause that is the kind of guy i am.

Annealed end of copper tube, insert wire in end and hammer end shut. Pull the wire out.

Couple pictures, one hammered shut and other showing water coming out end.

Gary


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