RE: [ATM] bending square aluminium tube

["Richard Klappal" <klappal@xnet.com>]

Some 50 years ago my father was a plumbing, heating, and sheetmetal
contractor and his shop had a number of tools for rolling sheetmetal into
ductwork.  These were hand-operated crank-driven machines; no such thing as
a motor.  The best idea would be similar to a hand-operated meet-grinder.

It consisted of three-wheels, 2 below and one over the workpiece, centered
between the bottom two rollers. The top center roller's position was
controlled by a wing-nut screw thread that controlled the radius being
rolled.  Tight curves required multiple passes, always lowering the center
wheel a bit at a time between passes.  Too big a 'bite' caused it to slip
and kink the work.

A mechanized, industrial machine to accomplish the work is shown at
http://www.toolsplus1.com/ringroller.htm (no endorsements implied, its just
a good illustration).  That image and a bit of imagination may give people
some ideas.


Richard Klappal


-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net]On Behalf
Of Bob May
Sent: Wednesday, 05 January, 2005 19:19
To: atm@atmlist.net
Subject: [ATM] bending square aluminium tube


You really need to make the rollers from metal rather than wood.  Wood will
work but you need to do some good precision work as the three wheel method
needs to hold the positions of the three wheels precisely.  Any slop or
flexibility will make the end product kinky as the forces aren't consistent.
Also, for small diameter bends, you need to do the work in stages til you
get where you need it.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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