Bending copper pipe to wide radius

get a pipe spring,

How wide is quite wide?

Cap up one end, fill with fine sand, cap the other end. Bend over suitable structure to make the curve. This could be you knee or two metal rollers. First anneal it. Where the curve is to be heat the copper to cherry red then quench in water. This makes it more pliable. You will need a substantial blow lamp to anneal it. You could try it cold first, it may work. When making the bend, do not make sharp pulls, Gentlly move up and down the bend pulling a small amount at a time.

For very wide radius, you can use your knee, and just pull on the pipe till it just yields, then move along a bit. For anything other than very shallow bends (say a meter radius), this method won't really work.

Only as long as the length of the spring.

You could bend a long radius with a shorter spring - you'd have to keep moving the spring along and bending just that part of the tube - it might be a bit tedious, though.

With a large radius it is best to use sand..

Quite possibly - if the radius is really long you wouldn't need anything! I wonder what it's for... gardening?

Not quite possible it is. This is not open to debate.

A 22mm pipe spring from a shed, mine comes from Wickes, a padded knee, = and a modicum of skill, and strength.

--=20 Dave Fawthrop

I've done this to bend 28mm copper, for which I don't have a proper pipe bender. However, your annealing process is for wrong metal. Copper is annealed at 700-800C (can be done as low as just over 400C, but you have to hold it at that temperature for a long time). There is no state change on cooling copper, so quenching is not required -- you can cool it over as long a period as you like. The annealing process for copper is reversed by flexing and vibration, not by slow cooling. If you quench it just for ease of handling, watch out for being burned by steam and boiling water spraying out.

For the sand, make sure it's dry or you'll have difficulty getting it out of the pipe afterwards. Even so, I sucked a large cotten wool ball through the pipe with a vacuum cleaner several times to remove as much sand residue as possible (this was a gas pipe, so I don't want sand getting into the boiler). A sand bag makes a good bending former. Do not try to bend near the end of the pipe -- saw any excess off afterwards.

For 22mm pipe rather than 28mm, I would however use a bending spring for this purpose. You should still anneal the pipe before bending it though.

I'm not sure about your terminology or where the last sentence comes in, but heating to red hot and quenching is fine.

No-one remember Peter Parry's instructions regarding pipe bending:

Mungo :-)

The fact that it works does not mean that it is the right technique. As Andrew says, the right method for a soft anneal is to bring the copper to dull red (600-800C), not cherry red (900-1650C). The method of cooling is also irrelevant. Quenching may be convenient, but it can also be quite dangerous if done improperly. Copper will anneal just as well if left to cool in air.

Colin Bignell

Didn't say it wasn't, just pointing out it isn't necessary to go to those lengths. In particular, quenching is used to preserve crystaline structures which would not normally exist at lower temperatures, by super-cooling them into a preserved state. There is no such cystaline state change with copper on cooling, so it's pointless. With copper, the reverse process to annealing is work-hardening, which is triggered by flexing and vibration.

For bending a large thick piece of copper, it should be reannealed during the bending process, or bent at a temperature which is high enough to keep annealing it throughout the process. This counteracts the work hardening caused by the bending itself. One way this used to be done with very large copper pipes was to fill them with molten lead under pressure instead of sand, at a suitable temperature.

Yes, yes...

I want you to tell me more about this, please.

And so - it will work, which is what I *said*.

I'm afraid you have imparted no extra knowlege whatever.

No - they work at a fixed radius, unless you can buy other formers.

The other common ways to bend pipe is to use a spring, or fill it with sand, plug the ends then bend it to what you want.

You obviously take no pride in your work if you do not prefer to use the right method.

Colin Bignell