bender for thin wall tubing
(c) m.s.gerritsen 2000-2004
This is the mandrel bender we use for the
bending of 10 x 0.5 mm tubing with a 25 mm radius.
The tube is clamped to the mandrel, and
a shoe runs along the outside of the tube being bent to keep it round.
A large bearing keeps it pressed in place.
Instead of working out the necessary angle with springback, for a single bend it is usually sufficient to calculate the theoretical lenght needed for the bend, and to measure the distance the tube slides up the interior rod.
this one is for 14 x 0.8mm cromo, r=40mm
This one bends 1"x 1/16". It was used to
put the bend in the Radical chainstays. The
stop on the pullingchain fixes the angle.
Detail of the actual bender. The tubing
is clamped to the mandrel. This has to be really tight otherwise the tubing
will slip and kink. The shoe is pressed against the tubing with an adjustable
This shows the rotating toolbit used to machine a proper circular groove