D profile tube

Help needed

I'm restoring a vintage car, the hood frame uses D profile tube, the size is 22mm x13mm, the original tubing has corroded and is not salvageable.

I have searched the net for D tube but can't find any this size.

If I acquired round steel tube, is it possible to profile it by using a swager with the correct dies.

If so, what type of tubing should I purchase?

Any help would be much appreciated.

I know it's not purist but couldn't you just run a router bit down the sides of some ally bar of near size to create that D.. assuming it's painted anyway no-one will know and it'll last longer.

I seem to remember that the K N Harris boiler book shows a tube with a flat down one side. OK so that was in copper but I think the same idea would work in steel.

He bored a hole in a wooded block and then milled a flat on one side to give the correct amount of flat and then hammered or pressed it down to the level of the wood.

It seems to me that that would work in steel in the sort of gauge you would expect to find on a car.

Brian

You should be able to shape round tube into a D. One method would be a grooved roller opposite a flat faced roller. Another method would be straight dies, one grooved to the contour of the tube and the other flat. The tube would be pressed between the dies, advanced and pressed again. In either method I suspect the tube will be bent and will need straightening. Getting the right sized tube to get the finished contour you wan may be a problem.

In principle such re-shaping is possible with fairly simple tooling providing the circumference of the finished D profile is little greater than that of the starting tube ensuring the tube is never in compression during the re-profile as such would almost certainly cause ripples. $6,400 question is how much larger does the finished profile have to be. I imagine you'd need to do the job in 3 or 4 passes, annealing if required. Difficult bit looks to be pulling neatly round the relatively sharp corners at each side of the flat.

Another point not to be overlooked is figuring out what material to start with. Need something soft and unstressed, cold drawn tube being very unsuitable. Unfortunately almost every application for ordinary tube requires stiffness so a bit of work hardening is acceptable and pretty much par for the course. Generally just needs to be workable with Hossfeld benders and the like.

Clive

What size D section are you trying to make?

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vintagengineer ... ^^^

Is there a visible seam in the old tube? could it be folded from sheet around a "D" shaped former and then slide the former out.

Former could be pre bent if there is a gentle curve to the tube and use solid material bent for the corners as it would not be easy to tightly bend the folded tube.

Have a chat with these guys:- **LINK**

John

www.vintagecarparts.co.uk sell 19mm x 10mm D shaped steel tubing

Jonathan