Pipe Bending

[marvoni]

I need to bend a 22mm class I pipe into a full 360 degree turn. I need the inside diameter of the bend to be a nominal 95mm. I'm hoping to avoid making up specific tooling because of the expense and wondered if anyone had any ideas how I might do it.

I have available a standard plumbing type 15/22mm pipe bender which will produce a finished radius of about 100mm so it's a starting point at least. I also have some bending springs and the usual general workshop tools. Any thoughts greatly appreciated.

 

[jtsplumbing]

What you making ??

 

[buckley plumb]

you might get a u bend but without rollers I doubt you would get a full 360 back over its self.you could call cylinder manufacturers and ask if they would make for you

 

[village idiot]

What you making ??

A wedding ring

 

[marvoni]

you might get a u bend but without rollers I doubt you would get a full 360 back over its self.you could call cylinder manufacturers and ask if they would make for you

Thanks, I have a hydraulic bender at work for thick walled pipe that can do a 180 degree bend, we use it for bending 316L seamless pipework for heat exchangers but I only have the bending dies for sizes between 1¼" and 3½ inch. To make a new bending die set just for a once-off isn't an option and I also can't do a continuous 360 on it without making 2 x 180's with a 4 inch flat section between them because of the way the tooling and clamps are arranged on the bed of the machine.

I need to find a way to do it by hand really. I was considering bending it 360 first with the hand bender then annealing the pipe then packing it full of glass beads or even sand and welding the ends closed, then attempt to work it by hand into a tighter circle. Yeah, I know it's probably not the ideal plan hence my quest for advice.

It's a component for a coffee roaster I'm making by the way. It will be visible so I need it to look half decent once I've finished bending it.

 

[albatross]

https://www.youtube.com/watch?v=-l-lMKlVFpA

Fill it with ice.

https://www.youtube.com/watch?v=9mlspVBAk2M
skip to 3 minutes in

 

[Chalked]

As above.
Anneal it, fill with water, freeze it, bend around somthing the diameter you need. Then reform the shape with hammers. Or force 1/2 ball bearings through to reform.

 

[Gray0689]

If you have the tooling to do 180 in stainless then weld it to make a 360

 

[leerdonald]

Interested to know if the annealing and bending works on that tight diameter without it kinking.

If not make up a copper spigot and solder two halves, polished up the solder line will hardly be noticeable.

 

[marvoni]

Unfortunately I don't have tooling for pipes as small as 22mm and I'd rather make it without a joint if I can for better aesthetics.

I'm going to try the ice trick tomorrow, I have plenty of pipe to play with so I'm not worried if it's a learning curve (no pun intended) with some attempts going in the scrap bin.

 

[Chalked]

How about using two of these? And offsetting at the top?

 

[marvoni]

I just had a dry run by hand. I made a 360 with the hand bender and with a bending spring inserted which was straight forward then annealed the pipe with the spring still in it and worked it by hand down to about 90mm. It just started to ripple on the internal surface at that diameter. The whole process took about 30 minutes then another hour and a half to get the spring back out .

I'll have another go with ice when I have the time and see if the results are any better.