Here's a copy of Mike Nixon's copper annealing process, message
number 31408 dated June 11th 2003
Re: [new_distillers] Re: bending copper tubing
w G wrote:
Subject: Re: [new_distillers] Re: bending copper tubing
OK, so How the hell U get salt in 27' of 1/4" tubing
LOL sounds like a bit of work to me..
1/4" tubing, if softened first by annealing ... heat until copper
starts to change color and then leave to cool (or quench quickly in
water ... it makes no difference with copper) should require no
filler to bend without kinking. Just wind slowly around a dowel or
other former, pulling hard on the free tubing as you do so. If you
must use salt, use very fine table salt. If the grains are still too
big, you can easily grind it finer with a pestle and mortar ... or
even a rolling pin on a hard flat surface. It powders very easily.
Taping a cone of paper around one end of the tubing makes a nice
funnel that doesn't take up space inside the tubing. Tap the tube
often, as advised by 'trailsendag'. Make sure the salt is very dry
before you start pouring by leaving it on a tray in a warm oven for
half an hour. Even iodised salt soaks up some water from the air and
will not pour as easily as bone dry salt.
You had me doubting myself charlieltc
But I'm willing to be corrected if I'm wrong
--- In email@example.com
> Hi guys
> Copper in tubular form by the very nature of the arch in the circle
> shape of the tubes cross section has inherent structural strength
> like all arches do.
> The arch in bridges is a prime example and virtually any hard-
> ish material that will hold its own shape will give good strength
> the arch shape). When this arch fails it just doesn't fail a
> it collapses completely. In our case it flattens.
> This structural strength in the arch of the ¼" pipe will
> let you bend your spiral for a condenser.
> As you start to bend the pipe into the spiral shape. The
> of the spiral pipe wall will compress. The outside of the spiral
> wall will stretch to the point of breaking down the arch shape
> section but not enough to break the pipe wall.
> Herein lies the problem of making the condenser. There is a
> very small section along the outside linear length of the pipe
> 1mm I'm guessing here) that will overstretch and break down the
> shape and flatten.
> What needs to happen is, this 1 mm stretch area needs to be
> spread out and lengthened but because the copper is wall is hard
> not very soft and not very stretchable. You need to put something
> hard inside that will hold it's own structural strength and hold
> pipe arch shape while stretching the outer edge of the copper
> But the hard outer edge of the copper pipe can still overcome the
> arch strength in the pipe cross section as we all know from
> experience and flatten.
> In order to let this outside edge stretch the new copper pipe
> needs to be softened or annealed. If you heat your new copper
> it's red hot and let it cool on its own slowly an naturally it will
> be soft and easy to work with. When you start your coil condenser
> the outside edge will stretch readily without over coming the
> structural strength of the pipe arch shape cross section. Well it
> worked for me on 10mm (3/8") pipe but taking it nice and easy.