Invention prototype - help please with bent half tube

[moegilla]

Invention prototype -- help please with bent half tube...

Hi all,
I am in the prototype phase of an invention and I need part that I can't get made and was looking for a few ideas.

As you can see the part is double-curved 16 gauge sheet metal. I brought it to a sheet metal shop and the guy told me it would cost an arm and a leg for 1, let alone the 4 I need.
I started thinking I could find a 90 degree elbow of some sort and cut it in half.

Any ideas?

 

[billblack]

You are correct. You can use exhaust header tubing pre-bent 90 or 180 degrees and then cut carefully with a bandsaw. While you show no dimensions, as long as it is less than 4 or 5 inch diameter, it should be fairly common. Some possible suppliers would be:
http://secure.chassisshop.com/categories/6202/
http://www.mandrel-bends.com/catalog/mandrel-bends-34/?osCsid=8891f790ee301685fa7aee2f667d22a9
http://www.cachassisworks.com/c-146-j-bends.aspx
http://www.speedwaymotors.com/Street-Rod-Exhaust-Tubing-Combo-Bends-Kits.html
I hope this helps.

 

[blkexp98]

Could you have someone with a mandrel bender just bend your choice of tube and have a water jet cut the tube? With a fixture and program for the water jet you could duplicate the 4 parts pretty close. I have no idea how much they would charge for shop time on a water jet though. If you made a jig I suppose you could cut the tube with a band saw but that leaves allot of room for a screw up and inconsistency.

Does the part have to be metal? If you could use fiberglass or some other composite you could make a mold pretty easy from a 90. That way you could also make any kind of mounting flanges if you need them as well. This would be the cheapest and easiest route. If it needs some heat protection I wonder how a few coats of a ceramic coating like air cure cerakote would work on the composite.