Packing a tube for bending

[ChipMaker4130]

Use the cerrobend and bend cold. We make hundreds of tight SS (304) bends in solid rounds daily at work, all cold. Attempts to ease bending of 304 by heating yield poor results. Its almost like the material is 'hot short', but technically it isn't. Tubing is, of course, different but you have a significant wall thickness and a cold bend might work well. If you have enough extra tube I strongly recommend giving it a try.

[tornitore45]

ChipMaker4130 I will listen to the voice of experience and try the cerrobend. What kind of support is needed? Like a "pulley" with a 1/2 round gullet?

[Bill Shields]

Yes...and it should be slightly deeper than tube diameter.

[ChipMaker4130]

I agree with Bill ^^. However, with Cerrobend the deep groove is less important and if you can get close to half-depth it should work.

[tornitore45]

I tend to plan way ahead; I am still a long way from making these parts but appreciate all the help and will report about the outcome. Thanks

[Russ Hanscom]

Here is a procedure I use for tight bends. Make up a die by cutting a groove of suitable diameter/radius and width in a piece of round stock. Next the grooved piece is cut into a 180 degree section and two 90 degree sections. The two 90 degree bits are attached to a backing plate. The dies and piece to be bent are set in a small hydraulic press, and away you go. By adjusting spacing you can almost get a 180 degree bend if one is needed. The rod in the photo is just over 1/2" dia.

[oldbrock]

Fill with lead and bend cold, Just melt it out after bending.

[liveaboard]

I like the bending jig Russ made.
The trouble is the swing of the rest of the tube when you're bending long pieces or complex 3d shapes. The press frame is likely to be in the way.

I made a bender for hydraulic tube; it might work for 1/2" plumbing pipe.
It bolts to my worktable/toolbox which is heavy and stable enough to take the force without difficulty. I've been using it a lot over the last couple of weeks, making new tubes for my tractor.
I also used it to bend 16mm solid rod.
Even with the table top bender, sometimes the table obstructs the tube; the bender can be bolted near either edge so the tail of the tube can hang over.

[Yorkshireman]

1.
The tube could be tightly packed with a molten Polymer to prevent the tube from folding or collapsing when bending ...

2.
One might even try to use molten Sugar for packing. Then the packing could be removed simply by bathing the bent tube in a Water Bath..
Molten Sugar can be a fire hazard, though ...

Johannes

[Bill Shields]

Cerro metal is a lot easier and liquefies in the 150F range..but then it does not taste quite as good on top of a cake as molten sugar

[tornitore45]

I will try to remember
Cerro metal for bending tubes
Sugar for sticky buns
There is not much sugar left around here these days. Lynda went on her usual Christmas baking frenzy.

Merry Christmas to all.