bending 4mm copper tubing

Any one know how to get a nice bend/curve on 4mm copper tube?

I have tried spring tube benders and it kinks and I now contemplate lead filling.

Do I make a tube bender?

Clive

Hi Clive, Have you tried a brake pipe bender? Cheap off ebay.

Nathan.

I have a tube bender - Hemingway. Very good, but over complex for the task- but quite excellent in the slightly larger sizes of tube.

If i'm not telling my granny, the operational guts of the thing is a groove, just over 1/2 th dia of thee tube to be bent. That stops it going oval and collapsing. So a lot of my smaller tubes I bend by using a ball nose cutter on a rod of the required bend radius, of about 75% dia depth, and bend the annealed tube around that.

3/16 tube I like the sliding shoe of the bender, but less than that a thumb and a groove does as well!

Don't know if it's still available, but Record did a "Mini Pipe Bender" in cast Alloy [painted Blue, of course], for tubes around this size.

Alternatively ... fill with Wood's Metal, not Lead; it melts at at about 80°C

MichaelG.

Edited By Michael Gilligan on 08/08/2012 23:42:23

Looks like the Record is still available ... at a price!

Edited By Michael Gilligan on 08/08/2012 23:47:05

It looks like I will make a mini Pipe bender as part of the exercise. I will need one for a later job anyway.

Clive

The specified bend is 4mm Radius so it is pretty tight bending with 4mm Dia. copper tube.

Its a bending jig for sure, I will start on it this evening when it is cooler as the sun is right in the front of the workshop.

Clive

I have read somewhere if you pack tube with dried sand and

seal the ends up you will get kink free bends, although I would

imagine in small bore pipes it may prove difficult to remove all the

sand.

Clive - 4mm rad in 4mm pipe is seriously tight. That will be an entertainment. I think you'll need the extra leverage of a bender to do that nicely.

There is a sort of ideal (typical) minimum dia/bend rad ratio. I have forgotten what it is, and someone may be able to help with that - but its not 1:1!!!!

Any way you can get away with it a bit wider than 1:1?

Clive, try Chris Heapy`s site. I think he does a table of sizes, pipes/radii etc.. If not, root around various sites run by individuals, because I`ve seen it somewhere!

John.

Very true, Paul.

A colleague tried to make a helix coil from 10 mm copper tube. The diameter of the coil was around 50-60 mm (from memory). He tried filling with sand and was unable to remove it afterwards. Then he had a brilliant idea: he filled the tube with table salt... Just put it in a bucket of water afterwards, and away it is. At the softening temperature of copper the salt does not melt. That way he produced a perfect coil.

Greetings, Hansrudolf

Clive,

You might find some useful guidance here

... He's talking slightly bigger sizes than 4mm, but the principles are explained.

MichaelG.

As I mentioned earlier ... Wood's Metal, or similar, is the best option for filling.

I think the Plumber's version is called CerroBend ... see here

Edited By Michael Gilligan on 09/08/2012 22:46:30

Edited By Michael Gilligan on 09/08/2012 22:59:41

Clive,

There is a very neat tube bender, described in photo's and a drawing, here

MichaelG.

I've heard of people filling the pipe with water and freezing it then bend

Thanks for that lead Michael, I have downloded the drwg and will study it to see if I can machine it with what I have.

Mark, I have taken that on board as my freezer is right alongside my workbench.

Clive

Hi Clive,

I use a product called 'Cerrobend', it looks like lead but melts in boiling water - just melt and fill the pipe, bend and a quick touch with a small torch melts it all out again for reuse.

Hope this is of use

Lofty

for ultra cheap you can fill it with water then put it in the freezer - work quickly once removed though!

I have made a bender to an American design but its as good as useless on the 4mm tube even when annealed.

I am now looking at one with a grooved bar that goes around with pipe as you bend it. I will still have to make it and I just need a little more time before I start. One of the main problems is the pipe is pulled through as you roll the wheel around. See my photos as there is a pic. of it there. This seems to make the rad. larger than what i want.

Clive

Edited By Clive Hartland on 04/11/2012 22:50:26

Hello Clive,

Commander W.T.Barker described a tube bender in Model Engineer number2383, 9th January, 1947.

It is for small copper tube up to 1/4" diameter maximum with a centre line radius of 1 1/2 to 2 diameters minimum. A anchored mandrel supports the inside of the tube at the point of bending.

I made one years ago and it does a first class job.

If you do not have access to the issue I can email you a copy of the article.

Regards, Graham

Graham, can you contact me through PM's and I can give you my email addy there.

Clive

Clive,

It will be very interesting if you do manage to achieve this.

With the notable exception of Michael Williams' Cut & Shut ... Every design, or method, mentioned so far seems to indicate that 1.5 diameters is a realistic minimum for the bend radius.

Please could you post some pictures of your experimental results?

Also ...if/when you do succeed; I think it would make an excellent subject for an article in MEW.

MichaelG.