Thread: How to bend 40mm copper pipe 180° ?

Clean it after welding it, just use emery where you want to weld. If you heat it and quench it most of the scale will fall off.
Are you after function or form? As in are you wanting to clean it up only so it weld well or is it to be a beautiful thing?
Yes wash it with water and dry it off before welding. What welding stick are you using. Ezyflow needs a flux but silfoss should be ok without if it’s clean enough. @40mm

@2post, I have silfos. ANd I dont care what it looks like, just so long as it works!

So, I have the 'spirits of salts' is that better than vinegar?

I’d give it a go if that’s what you have

@40mm have you considered other options aside from a in-fire wet back considering you have quite a small firebox? I would go with either a Yunca style water jacket heater that sits above the fire box or wrap 1/2 " copper around the flue as a heat scavenger but not welded to it. A tiny little pump can be used to push the water and circulate to a radiator. A friend who is a plumber has this set-up in his own house

Originally Posted by 2post

I’d give it a go if that’s what you have

Oh.... the fittings are quite expensive, being 40mm. I will do more research. Cheers though.

Originally Posted by Moa Hunter

@40mm have you considered other options aside from a in-fire wet back considering you have quite a small firebox? I would go with either a Yunca style water jacket heater that sits above the fire box or wrap 1/2 " copper around the flue as a heat scavenger but not welded to it. A tiny little pump can be used to push the water and circulate to a radiator. A friend who is a plumber has this set-up in his own house

The heat exchanger is 1.2m long and 40mm pipe, so wont fit anything else.... I have made a 'rocket stove' which is a very efficient type of fire.
It is made from two D size oxygen bottles welded together at a right angle.
The burn chamber is horizontal (on the ground and insulated) while the flue is vertical as usual.
Will burn bark and all the scesps from the wood pile etc without smoking the place out or choking.
Might even try some coal in it.

I think photos are required of this wondrous creation.

Originally Posted by Sidetrack

I think photos are required of this wondrous creation.

Here you go.

I will make a post for the home builds thread when I get some more pictures and progress.

Awesome! There's heaps of simple build rocket stoves designs now that use square tube. I've been tempted to build one for while with some leftover steel fence post I've got laying around. Will be watching this thread with interest!
https://www.google.com/search?q=rock...active&ssui=on

Go to to pit stop and see if they will bend it for you
They have hydraulic pipe benders
Would deal with copper like butter as Designed for steel and stainless
Probably only take them a couple of minutes and im sure they could be bribed with cold green glass or brown glass bottles

Make sure you have no airlocks, hahaha

Originally Posted by rambo-6mmrem

Go to to pit stop and see if they will bend it for you
They have hydraulic pipe benders
Would deal with copper like butter as Designed for steel and stainless
Probably only take them a couple of minutes and im sure they could be bribed with cold green glass or brown glass bottles

Cheers for the advice mate, I think the copper might be a bit soft and crease/ fold up? Maybe not.
Anyway, I have gone with two 90' bends as I already had them...

Will be making a thread about this project when I get back into it.

Originally Posted by Maca49

Make sure you have no airlocks, hahaha

not this project mate!

But I have my eyes on a mates old hot water cylinder....
Thinking of capping off all the safety valves etc and putting a bit of petrol inside it, then hard wire the heater.
A mattress bag or two full of oxygen taped to the outside and a couple road flares or something that will burn for a good while.

Just gotta find a paddock far enough from any stock, buildings, bush or houses and roads..... Not actually that easy in Auckland.


Should be an interesting 'science experiment'

Copper to copper joints only need to be clean (no flux) if using silphos. Is that a copper to steel joint at the open end? Copper to mild steel with silphos ( eziflo is better) will need braising flux and very clean steel, dont get the steel red hot.

Originally Posted by musket

Copper to copper joints only need to be clean (no flux) if using silphos. Is that a copper to steel joint at the open end? Copper to mild steel with silphos ( eziflo is better) will need braising flux and very clean steel, dont get the steel red hot.

Thanks for the advice @musket.
There is copper/copper and copper/brass joints to make.