re roll age tube bending:
I have, in the past built a decent roll cage using gas barrel (this is
seamed mild steel about 3.5mm wall thickness) i bent this with no
problem using a hydraulic pipe bender. these benders are in common use
where pipe fitters (gas or water) need to put lots of pipes in -they
must be used with the correct sized formers. however this cage was heavy
and would not have past motorsports material specification regs. i am
now building one for a tr7 v8 using the proper RAC motorsport
specification cold drawn seamless carbon steel (cds2). this is a
different kettle of fish and because it is a much harder steel will
collapse if bent using a normal bender -what you need is a mandrell
bender which has formers for both the inside and outside of the radius
of curvature. i tried a lot of places to buy this type of tubing and the
only place i could get it at a reasonable price (5 pounds per metre) was
at a roll cage manufacturer (safety devices, uk). they were also very
helpful in telling me what would bend it and what wouldnt ; alot of
plumbers have no idea about this type of tubing -be warned.
the answer is simple: if you want something for your own peace of mind
(or for posing) then build a cage out of the stuff that is commonly bent
using the bender you intend to use. if you want a cage you can get
passed by an approved motorsports body then check what they require and
do it properly. ie ask the people who normally work with it.
sorry to be a downer on this but if (as i have) you spend 75 pounds on
tube you dont want to chuck it in the bin and pay 300 for a good cage!
mike wynn
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