Help Bending 6061 T-6 Tube & Pipe

[ehsvp]

Hi,
I'm trying to obtain aluminum 1 1/4" tube and 2" schedule 40 pipe for rub rails and hand rails on a boat project. This material will be bent using a 3 roll bender and a die bender with follower shoe. I've been doing lots of research on the alloy and temper of material to use for the best results. I've called numerous metal distributors in the midwest and they all say they don't stock aluminum tube in the T-4 or T-0 tempers. A few of the suppliers want me to order a huge amount of material to make this "special order" worth it. I'd be curious to know how many of you simply use the 6061 T-6 and anneal it. My understanding is that the T-4 tempers will harden to T-6 over an extended period of time which further complicates my problems even if I can get the T-4 temper. The biggest bend in the tube will be 90 degrees and the schedule 40 pipe has to do a large curved bend along the bulwark at the bow of the boat. Any work arounds would be greatly appreciated.

[welderbob]

Hi Bob,
There was a good discussion on this subject a while ago. This should be the link. You may have to wade thru a few page . Kevin has a good explanation on why 6063 bend better than 6061. It does help to lube the die and pipe. Pam cooking spray works well. Good luck.
Oh and by the way , Your further behind on pictures than me.

viewtopic.php?f=3&t=2335&hilit=bending+pipe


just to keep life simpler in the shop, most of the smaller pipe that we order is 6063-T52. I wouldn't use it below the waterline ,but it does work well for hand rails. The half-pipe we put on the side of the boat is 2.5 sch 40 6061. It will bend around the side of the boat with a little perspiration.

You can also anneal it by heating with ox/acetylene torch . Blacken the pipe with just the Acetylene on, add Oxygen and heat until the black goes away.

Welderbob

[kmorin]

ehsvp, I'd use the term roller for a pyramid 3 roll 'bender' that is bending by rolling the pipe through and slowly tightening the top roller down as you go back and forth? A bend to me is a die with some type of outside 'former' or way to pull the pipe/tube into the die along a turn.

Rolling is different than bending as rolling is a gradual over-stretching beyond the elastic limit of the metal resulting in a radius roll like the bow roll you mention- and to me a bend is a single shot act in a die. Rolling 6061 is pretty reliable if the radius is 10 or 20 times the diameter of the pipe. In a bend most problems come from tearing the pipe or tube wall as the pipe is bound or 'galled' to the sides of the bending die. So, as Bob mentions, sanding the inside of the dies of a bender and then lubing with spray Pam pan spray will go along way to allowing the material to drag or flow along the inside of the die as its bent.

I don't anneal, but I do resort to 6063 (above the waterline ONLY) when I need bends that will not form reliably in 6061.

The reason to consider half pipe is that it bends cold with sequential clamps and tacks; AND you're welding the compressed edge relieving the stresses in compression at the bulwark edge. This allows the half pipe to lay fair along most bulwarks.

I've not worked with tube in hand rails only pipes almost all sched. 40 and 6061 T6 and I've not annealed any of this work except with the TIG welds' HAS around the legs and other intersections.

Cheers,
Kevin Morin
Kenai, AK

[ehsvp]

Kevin and Bob,
Thanks for your replies. Kevin, you were correct in that I'll be using a 3 die pyramid roller for the rub rails and a die bender for the hand rails. I'm going to purchase a small amount 6061 for the hand rail material and experiment with my die bender to be sure I can get the results I need. If the material is too problematic I'll work on getting 6063. It's great to have such knowledgeable resources available as you and Bob. Best wishes,

Bob