How To Bend Copper

How To Bend Copper

One of the reasons that copper tube is so popular
and chosen so often for making pipe work out of is the fact that actually, it’s a very
malleable metal. It means that you can form bends in it. You can change its shape. We choose table X or half hard copper. If
it was hard tempered, it would be too rigid to break. If it was soft copper, it wouldn’t
be strong enough to cope with being invertible sections. It would push out of shape. So, we go for
a temper which is half hard. This allows us to bend the copper tube into the shapes that
we need it. Why would we choose to bend rather than use
a fitting? To start with, there’s the cost element. Every bend that we pull will save
us the cost of a fitting. It also means if we make no joins, then there’s no chance of
us making another leak. So, the fewer fittings that we can use, the
fewer leaks that we’re likely to have. It also is a restriction to the flow. By choosing
a long slow bend very much like we have on motor ways, we have long slow bends rather
than short ones. It means that we can travel faster. The physics
are the same for water. If we pull a long slow bend, it means that the water can travel
faster in that change of direction than if we used a tight 90-degree fitting. So, the process for bending copper, we will
tend to use a scissor bender or a bending machine or copper pipe benders – a lot of
different ways of explaining them. Essentially, what we have is a former in which the bend
is going to be formed. We have the keep which is the piece that’s going to hold the copper
in place, to keep it in place, and then we have a roller arm and a back knife or guide
that locks in. So, that’s a fairly elaborate way of dealing
with a piece of copper tube. Why we’re doing that – if we took a piece of metal and simply
tried to bend it with our hands, it would collapse. The point of most stress would fold
in. The outer piece would fold out. The sides
would come out and the joint would simply, the pipe would simply collapse in on itself.
So, to stop that from happening, we trap it. We trap in a shape where it’s held in its
round shape. So, as the copper stretches during the bending process and tries to expand out
sideways, it can’t because it’s held in the circular shape. There is a line in which the
bend takes place. It pivots on that point, passes up through
the back knife, through the former, and through the roller arm. As long as the equipment is
in good condition and hasn’t worn then, the bend will take place at the point of contact.
Occasionally, bends will ripple. This tends to tell you that your equipment
is starting to wear out and that there is now a bit of play. So, as some of that expansion
and some of that stretches back into their own place, so to form the bend, we simply
bring the two arms down together. It forces the copper tube around the former. As we said, it’s held by all these other components.
So, it has to follow that line and it is in a position that it can’t collapse and it can’t
crease. We simply bring it around. There are several different ways of checking
when we achieve a 90-degree. One of the popular ways is to use a set square. And again, there
are different ways that we can use the set square. We can bring it down onto the back of the
back knife, or we can use our eye, then to line up those two, so the pipe is now in line
with the set square, or we can take the pipe out, physically put it onto the desk and set
within the square. What you’ll find is that as you practice, you’ll need to do less and
less checking and you’ll start to be able to see when a bend is achieved when you’ve
got to your 90. You remove it from the former, check the angle, and that’s how we bend metal.


  1. I think it would have been slightly clearer if you had actually shown what happens when you try to bend copper pipe without anything to stop it collapsing. The bit I found most helpful was when you said at (3:00 s), "there is a line where the bend will take place". I'm trying to work this sort of thing out. I have a diagram and I have to bend the pipe so that it exactly matches the diagram, so I need to learn exactly where the pipe bender is going to produce the bend.

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