Bending small copper tube

[Steve CrowParticipant @stevecrow46066]

I need to bend some 5/32 or 4mm copper tube to quite tight cl radius, around 10mm.

Checking past forum posts, the DuBro tube bender seems to be recommended.

Can any one tell me the minimum radius achievable with this tool? I can't find that information on the web.

Cheers

Steve

[Steve CrowParticipant @stevecrow46066]

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Steve CrowParticipant @stevecrow46066]

Thank you Bill, that sounds just about right for me scaled up.

By cl, I meant centre line radius ie. mid point. I should have been clearer.

Steve

[BOB BLACKSHAW 1Participant @bobblackshaw1]

I have been looking for a pipe bender that will take various small size tubes, looking at the Dubro on You Tube it looks so easy to make your own but looks like a one size tube. Prices for this bender are between £16 and £44 on line, a cheaper on Toolzone at £13 are they any good ? they take various sizes and for £13 its not worth the effort to make your own.

Bob

[Michael GilliganParticipant @michaelgilligan61133]

Posted by BOB BLACKSHAW on 29/10/2020 09:23:59:

I have been looking for a pipe bender that will take various small size tubes, […]

for £13 its not worth the effort to make your own.

.

… and yet : **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=167860

MichaelG.

[Nick WheelerParticipant @nickwheeler]

Posted by BOB BLACKSHAW on 29/10/2020 09:23:59:

I have been looking for a pipe bender that will take various small size tubes, looking at the Dubro on You Tube it looks so easy to make your own but looks like a one size tube. Prices for this bender are between £16 and £44 on line, a cheaper on Toolzone at £13 are they any good ? they take various sizes and for £13 its not worth the effort to make your own.

I bought one many years ago(although not from Toolzone) for bending brake pipes. It was so bad that after making one bend, I went back to bending them around a gate hinge. If you want to make accurate bends, or bends really near the ends of your pipes then making one of the properly designs engineered to do that will be necessary

[Martin ConnellyParticipant @martinconnelly55370]

I think the incentive for making your own tool is that the distance between bends can be reduced when you make your own tooling. Tools such as the Dubro have a fixed minimum distance between bends which may be too restrictive for some applications. Adding some sort of joint between bends to allow a cut and join operation for reduced distance between bends may be unacceptable at this size, too easy to block the bore, have a weak point or have an unacceptable bulge if a sleeve is used as a union.

Martin C

[not done it yetParticipant @notdoneityet]

I resort to my CZ Metal Bender if I want to bend anything small, neatly. I expect it would cope with the above application, even if I needed to make yet another mandrel for it.

[Glyn DaviesParticipant @glyndavies49417]

I also needed to make some tight bends close together on 5/32 tube. I bought the Dubro and its former wheel groove diameter is 11mm, so 5.5 mm +5/64" cl radius. The disadvantages of the Dubro are that it needs 12mm or so of straight tube before and after the bend and its plastic body means that it will only bend annealed tube.

I then wondered how I could make the simplest possible tool and came up with this:

Took half and hour to make and although restricted to 90 degree bends, it works a treat on un-annealed tube. Groove diameter of the former is 7.5mm. Make sure the groove is deeper than half the diameter of the tube so the tube is positively prevented from going oval during bending and the groove in the clamping block needs to be shallow enough that the tube is solidly clamped when in the vice.

[geoff walker 1Participant @geoffwalker1]

I'm really pleased that I made the pipe bender in the last MEW.

Not that difficult to make and gives really neat bends.

Made some 1/8" formers yesterday and then made my first component part.

No prizes for guessing what it is?

geoff

[BazyleParticipant @bazyle]

Funnily enough we discussed tube bending on yesterday's St Albans club zoom. Woods Metal was sugested as an aid and first put olive oil in pipe to stop it sticking.

[BazyleParticipant @bazyle]

Posted by geoff walker 1 on 29/10/2020 13:09:27:

No prizes for guessing what it is?

geoff

Your wife is not going to be happy with the sink taking 6 hours to drain through such a small u-bend

[geoff walker 1Participant @geoffwalker1]

Posted by geoff walker 1 on 29/10/2020 13:09:27:

No prizes for guessing what it is?

geoff

Your wife is not going to be happy with the sink taking 6 hours to drain through such a small u-bend

Oh yes Bazyle!

My wife does complain a lot.

Only yesterday the handle came of a pan lid.

I was charged with fixing it right away, which I did.

Of course she complained, not good enough she said.

No pleasing some

Geoff

[Steve CrowParticipant @stevecrow46066]

Thank you all for responding.

It looks like the Dubro tool is out of the question. The radius is ok but I need to make bends close together.

I really like Glyn's simple bender but I am also Intrigued by Geoff's.

I don't get MEW but would like access to the plans and article. If I subscribe to a digital edition, will I get this and previous articles as part of the digital archive?

Many thanks

Steve

[geoff walker 1Participant @geoffwalker1]

Steve there is a thread on here for pipe bender I have made.

Search for Derek browns pipe bender MEW297 and you will find it.

There are numerous drawings in the thread but a read of the article would help if you intend to make it.

Geoff

[Fowlers FuryParticipant @fowlersfury]

Have you ever looked at "David Carpenter's website"?
Some while back there was a short construction series by "Artisan" on making a tube bender.

As you'll see above, he made no claims for originality. I made one to the design and am very impressed with how well it works, producing tight bends without kinking or other unwanted distortions.

Artisan showed examples of bends his device had produced:-

David Carpenter has transferred most of his older articles to DVDs now which must be a bargain at GBP 7.90 each. Just check on his DVD section on the website.

I made a few alterations to the design such as a stronger baseplate and also discovered an easy and quick way to make the many rollers. I'm happy to provide details if you decide to go this route.

[Harry WilkesParticipant @harrywilkes58467]

Posted by geoff walker 1 on 29/10/2020 13:09:27:

I'm really pleased that I made the pipe bender in the last MEW.

Not that difficult to make and gives really neat bends.

Made some 1/8" formers yesterday and then made my first component part.

No prizes for guessing what it is?

geoff

Geoff would that be issue 297 ?

H

[geoff walker 1Participant @geoffwalker1]

Yes Harry that's right issue 297

Do have a look at the Derek brown thread.

There are some issues with the article in 297 which are discussed in the thread

Geoff

[geoff walker 1Participant @geoffwalker1]

Double post

Edited By geoff walker 1 on 29/10/2020 18:31:19

[Harry WilkesParticipant @harrywilkes58467]

Posted by geoff walker 1 on 29/10/2020 18:23:56:

Yes Harry that's right issue 297

Do have a look at the Derek brown thread.

There are some issues with the article in 297 which are discussed in the thread

Geoff

Thanks

H

[Cornish JackParticipant @cornishjack]

GW1 – Your wife may not appreciate your efforts but, I do! As de facto 'cook' for self and partner, my constantly less effective grip makes 'normal' round centrally placed knobs increasingly difficult to grasp. Your 'repair' as a properly incorporated design would make life much easier!

Patent Office, anyone?

rgds

Bill

[geoff walker 1Participant @geoffwalker1]

Cheers Bill

It's nice to be appreciated!!

Geoff

[Henry ArtistParticipant @henryartist43508]

What I love about engineering in general is that there is always more than one way of doing things so here a a couple of alternatives –

Don't bother bending the pipe. Keep it straight and use elbows and tee's when you want to turn a corner. These are available as castings or ready made items. Or you could machine/fabricate your own from bar stock.

When using thin walled tube (particularly brass) it has a tendency to collapse if bent through a tight radius. Anneal the pipe, let it cool, then pack it with something that will bend but won't let the pipe collapse. One approach is to plug one end of the pipe, fill it with table salt and plug the other end. The advantage with this method is the salt is easy to remove once the bending is done. However, depending on the internal diameter of the pipe or tube this procedure gets progressively more fiddly as the diameter gets smaller.

For (really) small diameter tube insert a styrene rod that is a close sliding fit. Bend the tube into whatever shape takes your fancy. Remove the styrene rod by burning it out with a blowtorch.

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