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bending 4mm copper tubing

Difficulty bending to a nice curve

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Clive Hartland08/08/2012 21:49:06
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2607 forum posts
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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

Nathan Sharpe08/08/2012 22:02:25
152 forum posts

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

Nathan.

mgj08/08/2012 23:08:15
1008 forum posts
14 photos

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!

Michael Gilligan08/08/2012 23:38:47
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16422 forum posts
715 photos

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

Clive Hartland09/08/2012 07:37:43
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2607 forum posts
40 photos

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

Clive Hartland09/08/2012 14:35:18
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2607 forum posts
40 photos

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

paul rayner09/08/2012 16:46:25
160 forum posts
44 photos

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.

mgj09/08/2012 21:43:29
1008 forum posts
14 photos

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?

DMB09/08/2012 22:11:30
1016 forum posts

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.

Versaboss09/08/2012 22:37:50
458 forum posts
51 photos
Posted by paul rayner on 09/08/2012 16:46:25:

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.

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

Michael Gilligan09/08/2012 22:45:17
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16422 forum posts
715 photos

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

Michael Gilligan09/08/2012 23:10:45
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16422 forum posts
715 photos

Clive,

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

MichaelG.

mark mc13/08/2012 13:38:16
92 forum posts
16 photos

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

Clive Hartland13/08/2012 18:06:34
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2607 forum posts
40 photos

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

FMES03/11/2012 22:57:59
605 forum posts
2 photos

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

fizzy04/11/2012 20:24:26
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1734 forum posts
116 photos

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

Clive Hartland04/11/2012 22:48:58
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2607 forum posts
40 photos

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

John Ockleshaw 105/11/2012 02:23:51
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48 forum posts
7 photos

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

Clive Hartland05/11/2012 07:42:33
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2607 forum posts
40 photos

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

Clive

Michael Gilligan05/11/2012 08:22:25
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16422 forum posts
715 photos
Posted by Clive Hartland on 09/08/2012 14:35:18:

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

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.

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