Bending 3/8" copper pipe

[Matty F]

I need to put a couple of 1 inch radius bends in 3/8" OD copper pipe, without flattening it. Any clever ways? I do have some pipe springs for much larger pipe, but not that small.

[Mungo "Two Sheds" Toadfoot]

Fill it with dry sand then bend it round a something?

Si

[fred]

In article , Matty F writes

Do they have CPC in NZ :-?

is the same for all sizes and the one I have here will accommodate a 1" radius no problem. Do you have any pulleys with a 3/8" slot to get you started?

[tony sayer]

In article , Matty F scribeth thus

If you mean 10 mm pipe then bending springs are made for that diameter. I've got one here. We used the pipe to make a rather special radio aerial that was odd shaped;))..

Failing that, heat it anneal it then stuff it with sand thats a possible, needs some care 'tho..

[Spamlet]

Reading the other replies I don't see the various fills from working.

If you really do need to bend it (are there no ready made solder corners for this size pipe?), then fill it with molten lead which you can melt in a small measuring cup or tin mug or ladle etc on the gas ring or with a blow lamp. Put the bottom end of the tube in sand; hold the top with pliers and fill it up. When cool this will give you the best chance of not flattening the pipe when you bend it. When bent heat up pipe and pour out lead.

However, with the small radius, if you don't allow the pipe to flatten, it is quite likely to split on the outside and buckle up on the inside, so if I were you I would be asking about 90 degree couplings or flexible pipe, and have plenty of back up samples ready.

S

[A Plumber]

You can also use an "external bending spring", ie the pipe goes inside the spring then bend normaly. used often on microbore pipe.

[Cicero]

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A 10mm external spring or two of these:

[cynic]

Bending tools (Rothenberger) are available for this size, mostly used for 6, 8 or 10 mm copper fuel pipe but the 10mm will give satisfactory result with 3/8" pipe. Ask an oil fired heating engineer as he will probably make the bend for you with an appropriate drinking voucher changing hands. The radius might be slightly greater than 1" but not appreciably so. I see you are in NZ so a bit far to offer for me

[pete]

One technique that's used to get thick cables around sharp corners without damaging it is to change the level of the cable as it goes around the corner. So for example if the cable starts off at a height of (say) 1m then instead of keeping that height all the way around, you bend the cable some distance before the corner (still against the wall) down towards the corner - so it's at about 90° pointing towards the floor when you reach the corner. Now, to get round the corner, the cable only needs to be twisted, not bent and then another 90° bend at a large radius once it's past the corner brings it out parallel to the wall, but lower than on the first side by twice the radius of the curves you put in it.

If all your pipe has to do is get around a corner, that might do the trick.

[Pete Verdon]

When I had to do that I made an appropriately-sized wooden former by filing a groove round a block. The groove fit the pipe tightly at the sides, so it couldn't spread out to flatten. It did pucker slightly on the inside of the bend, but good enough for what I needed.

Pete

[Michael Chare]

To do this, I bought 2" diameter plastic wheel with a tyre on it from local hardware shop. (Possibly for a pram/trolley)

I removed the tyre, used mole grips to hold pipe to wheel at one point and then carefully bent pipe round the wheel. Normal central heating pipe benders work in the same way. (Central heating oil pipe.)

I also have an external spring, and you can get small pipe benders.

Michael Chare

[Matty F]

I could bend the pipe between two metal plates in a vise. But first I will have a look at the springs that I've got.

The pipe is underneath this new oiler box that I made:

pipe does seem very soft but tends to flatten when bent.

[Dave Liquorice]

Thats why you need a former to stop the sides spreading remember that the outside of the bend needs to stretch and the inside compress. The compression of the inside is why you get puckers or ripples on the inside of bends that are too tight or badly pulled.

[mark]

made:

a banjo bolt to connect and then you won`t need to bend it.

[martop]

May sound silly but have you thought about filling the pipe with water and freezing it then bending it around a former ? Same methods used for bending pipe work on musical instruments.

Mart.

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[Michael Chare]

Interesting idea, but putting the pipe in a freezer would have been a bit of a challenge in my case, There would also have been the problem of getting all the water out of the pipe afterwards. :-)

[Matty F]

I was about to try sand, then discovered an external spring bender of the right size. It was rather hard to get the spring off afterwards. I tried unwinding the spring but had no luck. I had to bend the pipe back a bit to get the spring off. Anyway it's finished now:

may have to move the bend up a bit when I see where the floorboards are going to be!

Perhaps there is a better lubricant than the CRC that I used so that the spring would slide off easier.

[tony sayer]

JOOI what is the rest of that machine its connected to?...

[Matty F]

1891 Baldwin steam tram naked: with its clothes on so it doesn't frighten the horses: oilers feed oil to the axles so I have to make four of them.

[tony sayer]

Awww, lovely:))...

They still have Horses then;?...