Bending
Aluminium Tube
You
may have noticed in other project pages that I have used 19mm Anodised
Aluminium tubing bent to shape, for example for my Sprayhood
Grab Rail, the vertical poles of my cockpit tent and for the support of my
pivoting table. How did the tubing get bent without a bending machine? Simple…..
First
the desired curve is drawn on a cardboard template. Next a couple of stout
softwood timbers are set up in my vintage workmate. The timbers should
preferably be round in section or if not they should be rounded off at the
working area just above the workmate’s work surface. I happen to have a piece
of broken oar and an offcut of banister rail. The
timbers are set a short distance apart and at their bottom ends near the floor
a spacer is put between them and then the bottom ends are lashed together -
mainly to stop the spacer falling out.
The
tubing is then inserted between the timbers and bent. There are two keys to
successful technique.
The
first is “a little bit at a time”. You do not want to end up with a bend the
same diameter as the timber so don’t make big bends.
Bend the tube just enough so that some bend will take and not spring back. Then
push the tube in further (or pull it out) and make another small bend a little
further on. Every few bends check your work against the line on your cardboard
template then make a few more little bends. You will notice that the anodised
surface adopts a lighter slightly crazed appearance where it is stretched. This
is inevitable and has not proven to be a problem.
The
second is “keep it flat”. For most jobs you will want to bend the tubing in one
plane only. The danger is of lifting the end you are pulling on to make the
bend. This should be avoided so it is important to keep concentration and use
the surface of the bench as a guide to keep your bending “on the level”. Try to
imagine the bench having a much bigger surface and keep both ends of your tube
at the level of the bench surface.
This
is how I have done it – it worked for me. I am sure other methods can be worked
out if you have different resources available. One other method that occurs to
me but which I have not tried is to insert the tube into a bell mouthed hole in
a stout timber and use that as the fulcrum. The hole would need to be much bigger
than the tubing in order to avoid sharp bends but whichever way you do it, the point is that if you or a friend have bending
springs and a bending machine fine. If not you don’t need special tools to bend
aluminium tubing.