Aluminium Sch 40 6061 tube bending for bimini frame

[RaymondR]

This image shows the anexe rails which go all the way around the bimini into which the shade curtains I use fit. It also illustrated how I avoided sharp corners on the panel frame.

[Cpt Mark]

Bending tube or pipe without kinking.

You need either a tubing bender or a pipe bender. The mandrels must be exact or it will kink every time. Both can purchased at harbor freight. Pipe benders are cheap as there are a lot more of them I guess.

Conduit bender will not work on the schedule 40 anything. Conduit is thin wall stuff.

If using pipe, you might even try an independent muffler shop as they have pipe benders.

You might consider enrolling in a machine shop and welding class at your local junior college. You'd have all the tools there to use for free.

[Cheechako]

Sched 40 or 80 will be pipe as mentioned. Tubind is measured on the outside diameter. So 1" tubing will be 1" outside.
If you are not bending too tight a radius a simple hand conduit bender may work fine.
Do not heat the aluminum! You shouldn't need to anyway. Sched 40 should be plenty rigid enough.
If you can find it, or find tubing instead of pipe, T3 or T4 hardness will be easier to bend.

The other thing to think about is can you find it in SS at a used marine parts place in Seattle or Bellingham? It's been years and I dont know if these places still exist, but the last one I was at in Bellingham had dozens of bimini style bent 1" SS arches.

[ejs]

You may already know this but the 6061 refers to the alloy and the T6 refers to the heat treating. T6 is hard, T4 is less so and might be bendable, T0 is the annealed state. Steve is right that you will be able to make the bends if you anneal per his instructions. After it is all bent to the shape you want, you can do the heating trick again, only this time quench the hot aluminum in a big bucket of water (or the ocean since you're on a boat). This will get you some of the heat treated strength back. Not all the way to T6, though.
Cheers, Eric

[MVDarlin]

Cheap trick. Fill the tubes with sand before you bend.

[vic008]

Have thought the same, but so far the grubscrews are holding up. Does anyone else think the single grubscrew is not adequate?

[cyan]

Originally Posted by vic008

Have thought the same, but so far the grubscrews are holding up. Does anyone else think the single grubscrew is not adequate?

I’ve had great results (and peace of mind) by replacing all the grub screws used in my Speed-Rail fittings by much longer grub screws to go completely through one wall of the pipe. (movie-set trick where a failure/ loose screw could be fatal) In my case, I used 1-1/2” long 3/8-16 grub screws instead of the 1/2” length screws provided.

Test fit the pipe, tighten the screw to mark location, remove pipe and drill ONE hole on that mark with a diameter just large enough to pass the longer grub. Reassemble, and tighten the long grub all the way down so that the inside of the pipe is clamped to the inside of the fitting on the far side. Even if your screw loosens up quite a bit, the fitting holds. Same look, but more reliable with this inexpensive fastener swap out.