OT tube bending

Bending thin wall tube to a sharp radius is an art form even with top grade production equipment. For a one off project, I'd suggest using a vendor of stock bends. Cut and weld. My local supplier of these is

There are quite few others, especially in NASCAR country.

Steve wrote:

I am in the UK ! Where IS NASCAR country, out of interest ?

Sources of header parts are a lot thinner on the ground here.

Steve

Awhile back somebody over on RCM (rec.crafts.metalworking) was using a torch to shrink one side of tubing making some very impressive bends. I think it was much smaller diameter but the principle should still apply. I have usually cut radial slots and then welded the inside to form bends. It is slow and tedious but it works. Not show quality stuff though. I always used an O/A torch for the welds .. but then that was all done before I got TIG :) Glenn

Sorry about that!! :)

Actually, the source I mentioned is a distributor, buys bends made to his specs in quantities of a hundred or so, sell them by the one or two. I used to supply to him when I was active in that industry. Your best bet is to find a small bending shop using "draw benders with mandrels" Checking around for "tube fabricators" is another search term.

See if you can design your headers using a single diameter tube with a common bend radius.

I think of NASCAR country as centered in Georgia, US. There are literally dozens of shops building NASCAR machines, dragsters, etc as well as the supplier base like the tubing benders.

steve wrote:

The Urbanites view of Nascar Country

"I think this is because of your belief in biological Marxism. As a genetic communist you feel that noticing behavioural patterns relating to race would cause a conflict with your belief in biological Marxism." Big Pete, famous Usenet Racist

The center of NASCAR is Mooresville, North Carolina. The majority of the teams and suppliers have their shops there. It is a great place to visit as most of the shops invite visitors, and it is a real thrill to hear the engines being dyno-tested as you drive by the beautiful, huge facilities.

NASCAR country is the whole USA, in my opinion. And I am not really much of a fan!

You can buy elbows and weld them into the tubes.

Harbor Freight Tools sells some budget-priced hydraulic benders. In plumbing you can use springs (inside or out) to keep the tubing from kinking or collapsing during a bend. So, find a garage door spring of the right diameter to slip inside or over the tube and try bending it (might have to cut off the end loops so it'll fit over or in the tube). You can find them at most building centers/hardware stores. I don't know why you only need

2-3". Maybe once formed you can cut the short length you seek from the longer tube. Not something I've actually done, but me thinks it'll work.

Roy J, what about using the garage door spring. Won't that keep the thin tube from kinking? P.S. disregard the humorous reference to the 2-3" 'length' in my previous post. I know Steve was referring to the 2-3" 'diameter' and not the 'length' (and that's the story I'm sticking to!)

The pros use a mandrel equiped draw bender to do the thin wall tube. It has full support inside and outside, the metal doesn't have a chance to go anywhere it isn't supposed to. Kinks are actually a collapse inward.

I've tried pack> Roy J, what about using the garage door spring. Won't that keep the thin

The garage door springs I'm referring to are tension springs. They are not the ones for roll-up, sectional doors. They have eye-loops on their ends to attach the door to anchor points. As for locating one in a tube you'd simply attach rope to it's ends and position it inside, centered on the bend radii. If the tubing is positioned inside the spring the positioning would be easier. Seems like the 'inside ' spring method would better serve to avoid kinking, though.

RoyJ, Pulling the ends of an extension spring (tension) will cause it to stretch and its diameter will be reduced. Diameter varies directly with the tension applied. I don't see your logic in applying torsion to the extension spring in an attempt to reduce its diameter. Ted