Bending Metal Tubes

im4gine3

im4gine3

im4gine3

Associate
Joined
7 Oct 2015
Posts
1,225
May be a bit of a silly question, but i've been mainly using Acrylic tubes, so have a bit of experience bending these.. however for those which are using metal tubes. e.g.

Brass hard tube 14mm AD 220x300mm 90 degrees - Pack of 4 - Silver​


What tools do you use to bend these? I assume its not just brute force.. and i assume just a regular hacksaw is enough to cut them. How about RFP bits to chamfer or no?

I've only really seen people with pre-bent tubes and not any which multiple bends (usually using angled fittings to make secondary/tertiary bends). I take it this is uncommon
 
im4gine3 said:
May be a bit of a silly question, but i've been mainly using Acrylic tubes, so have a bit of experience bending these.. however for those which are using metal tubes. e.g.

Brass hard tube 14mm AD 220x300mm 90 degrees - Pack of 4 - Silver​


What tools do you use to bend these? I assume its not just brute force.. and i assume just a regular hacksaw is enough to cut them. How about RFP bits to chamfer or no?

I've only really seen people with pre-bent tubes and not any which multiple bends (usually using angled fittings to make secondary/tertiary bends). I take it this is uncommon
Click to expand...

I've used metal tubes a lot but never bent them myself. You need to compact the inside with something like sand and then use a Pipe bender to get the 90 degree bends. You'll see other creators who use metal tubes don't bend them that far and usually go with long elongated lengths to create bends OR they use copper copper solder ring elbows and create a join that way.
 
They need to be supported or you risk the tube flattening out, even collapsing and crimping flat at a point.

Tube bending device or machine which presses the tube around a groove matching the pipe size.

Internal or external pipe bending springs - generally this is for "soft" copper plumbing pipe.
 
Have seen someone in the forums in the past
Tried to bend them with
Very little success because the wall on them
Is so thin

Sand probably won't work
It still has too much give in it
Unless you tamp it as you fill it up
But then it may end up being too inflexible
Pipe bending spring probably the best bet if you can
Get one in the correct diameter
Maybe even a silicone insert in correct diameter
Though that may also be too compressible

Hacksaw will cut it fine
Or for a better finish use a pipe cutter
The type you turn around the pipe
And adjust the cutting wheel as you go
 
Last edited:
hmm sees like a right faff doing this.. probably why we only see single bends/pre bends for this tube.

Thanks anyways.. something to thing about
 
Mcnumpty2323 said:
Have seen someone in the forums in the past
Tried to bend them with
Very little success because the wall on them
Is so thin

Sand probably won't work
It still has too much give in it
Unless you tamp it as you fill it up
But then it may end up being too inflexible
Pipe bending spring probably the best bet if you can
Get one in the correct diameter
Maybe even a silicone insert in correct diameter
Though that may also be too compressible

Hacksaw will cut it fine
Or for a better finish use a pipe cutter
The type you turn around the pipe
And adjust the cutting wheel as you go
Click to expand...

You would have to compact the sand in there really tight to retain any conformity when bending, it's near impossibly without some sort of press and you'd need a good seal on the other end too.
 
Bending soft copper tube is simply enough, plumbers do it all the time. But it's raw, unfinished copper. You can't get something like pre-plated brass tube and bend it because the finish will flake and the tube itself probably crack because it's been annealed.

Stainless steel tube can be done by hand just about but you need a big-ass pipe bender, lots of oomph and a large bending radius.
 
LePhuronn said:
Bending soft copper tube is simply enough, plumbers do it all the time. But it's raw, unfinished copper. You can't get something like pre-plated brass tube and bend it because the finish will flake and the tube itself probably crack because it's been annealed.

Stainless steel tube can be done by hand just about but you need a big-ass pipe bender, lots of oomph and a large bending radius.
Click to expand...

Yeah i was thinking the same.. I know pipe benders ain't cheap, and was tempted to call in the plumber for a silly excuse and 'nudge' him to let me borrow his
 
Pipe benders that can handle PC watercooling-sized copper tube don't cost the earth, but finding them is tricky. Handling 12mm OD tube would be a "micro" bender and can be had for about £20-30. Handling stainless steel puts you over a hundred quid though.

Your plumber might be much use though. 14mm and 16mm aren't plumbing sizes, so could you use a 15mm bender instead? No idea.

The big thing for me though is the large bend radius. I was looking at doing copper in a small build and the radius of about 40mm in a 12mm bender is far too big. You could get bending springs though and fashion your own mandrels, but you might start hitting repeatability and quality issues.
 
So after a bit of reading
You may have to anneal the tubing first
Then there's a few options
Fill with soapy water and freeze
Then bend
Fill with bismuth alloy and bend
Fill with cerrobend or cerrosafe and bend its bismuth,lead,cadmium and tin
So basically a brand name bismuth alloy
Or from further back in history
Brass instruments were bent using pine rosin

All of those except the freeze method
Use stuff that melts/becomes liquid at low temp
So you heat it pour it in
Wait till it solidifies then bend
Then apply heat and pour it out again
Actually wondered if could do similar with candle wax
 
You need to have the right type of copper pipe to be able to bend it without it either collapsing or cracking at the bend, this is usually supplied as a coil. Other metals are usually too hard to bend well.

I've done a few builds in the past using 10mm central heating pipe. I first buy it in a coil to practice with it before buying the same stuff but chromed for the final pieces. It's soft enough for it to bend without it affecting the chrome finish. Getting it straight is a pain so I used a "Kwik" tool which does a good job by running it up and down the pipe until it's straight enough.

embed


I used a pipe cutter with a built in reamer to get nice ends in the pipe so as not cut the o-rings in the fittings. Measure lots, cut lots and then bend lots using a pipe bender (Rothenberger, the red thing in the image below), and waste lots if you are picky about the bend!

embed


With enough practice (and material) you can eventually get nice results. More on that build here.

embed


I recently played with some scraps of chromed copper in my latest build (link in sig) but the plan was always to use clear acrylic tubing.

embed


Hope this helps and doesn't deter you too much!
 
You must log in or register to reply here.
Back
Top Bottom