I need to bend some 22mm copper pipe into quite a wide radius curve -
is it possible to use conventional pipe benders to do this (the type
with long handles)?
It's just that from looking at them, they appear to have a fixed radius
former - or is there a way of increasing the radius of the curve you
make?
Above all, I need to produce smooth curves - is there a better way of
doing it?
Any advice would be appreciated...
Nigel Lord
You could bend a long radius with a shorter spring - you'd
have to keep moving the spring along and bending just that
part of the tube - it might be a bit tedious, though.
Cap up one end, fill with fine sand, cap the other end. Bend over suitable
structure to make the curve. This could be you knee or two metal rollers.
First anneal it. Where the curve is to be heat the copper to cherry red
then quench in water. This makes it more pliable. You will need a
substantial blow lamp to anneal it. You could try it cold first, it may
work. When making the bend, do not make sharp pulls, Gentlly move up and
down the bend pulling a small amount at a time.
I've done this to bend 28mm copper, for which I don't have
a proper pipe bender. However, your annealing process is for
wrong metal. Copper is annealed at 700-800C (can be done as
low as just over 400C, but you have to hold it at that
temperature for a long time). There is no state change on
cooling copper, so quenching is not required -- you can cool
it over as long a period as you like. The annealing process
for copper is reversed by flexing and vibration, not by slow
cooling. If you quench it just for ease of handling, watch
out for being burned by steam and boiling water spraying out.
For the sand, make sure it's dry or you'll have difficulty
getting it out of the pipe afterwards. Even so, I sucked a
large cotten wool ball through the pipe with a vacuum cleaner
several times to remove as much sand residue as possible (this
was a gas pipe, so I don't want sand getting into the boiler).
A sand bag makes a good bending former. Do not try to bend
near the end of the pipe -- saw any excess off afterwards.
For 22mm pipe rather than 28mm, I would however use a bending
spring for this purpose. You should still anneal the pipe
before bending it though.
The fact that it works does not mean that it is the right technique. As
Andrew says, the right method for a soft anneal is to bring the copper to
dull red (600-800C), not cherry red (900-1650C). The method of cooling is
also irrelevant. Quenching may be convenient, but it can also be quite
dangerous if done improperly. Copper will anneal just as well if left to
cool in air.
Colin Bignell
On Fri, 13 Jan 2006 00:01:33 -0000, "nightjar" <nightjar@<insert my surname
here>.uk.com> wrote:>
*Right* is a concept which exists only in the minds of *people*.
There are always different ideas of *right* held by different groups of
people.
What OP is saying is follow my opinion of right.
--
Dave Fawthrop <dave hyphenologist co uk>
17,000 free e-books at Project Gutenberg! http://www.gutenberg.net
For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/
Copper anneals at dull red heat and melts within the range of cherry red
heat. Presuming that melting the tube is an undesirable result, the right
method is set by physics and is not simply an opinion.
Colin Bignell
On Fri, 13 Jan 2006 08:20:23 -0000, "nightjar" <nightjar@<insert my surname
here>.uk.com> wrote:>
The ?laws? of science, including physics, are *only* an agreement by
scientists in general that this is the best idea of reality we have at the
moment. Popper IIRC believes that all "Scientific laws" will be
overturned or drastically modified within 200 years of formulation.
http://en.wikipedia.org/wiki/Scientific_law
generalization based on empirical observations. They are conclusions or
hypotheses which have been confirmed by repeated scientific experiments
over many years, and which have become accepted universally within the
scientific community.<<<
Also http://en.wikipedia.org/wiki/Karl_Popper
A classic example of laws being found wrong is Newton's Laws of Motion,
http://en.wikipedia.org/wiki/Newton's_laws_of_motion which still describe
motion of most bodies in an *Engineering* sense perfectly. However they
fail on an atomic scale when Quantum physics describes atomic and sub
atomic particles better. Also they fail on an astronomical scale where
Einstein's theories of relativity give better results
--
Dave Fawthrop <dave hyphenologist co uk>
17,000 free e-books at Project Gutenberg! http://www.gutenberg.net
For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/
Which is utterly irrelevant.
Deeper understanding of the physics of copper does not change the
underlying physics of how it behaves when heated.
The mechanics of forming copper have not changed throughout human
history - and what happens when you bend it and heat it is unlikely to
change in the future.
New physical laws have to fit within existing observations, which means
that it's very, very unlikely anyone will work out a different way to
anneal copper using heat.
Many areas of physics have been explored with exquisitely sensitive
instruments, and all the existing laws work down to those scales.
If you have a new theory, it is only useful if it conforms to all
existing experiments - or it's patently false, or if it differs in some
way from existing theory in some way that's testable.
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