Bending thin walled brass tube

[mickParticipant @mick65121]

I've got to bend a quantity of 5/16'' dia. x 0.25'' thick walled brass tube to form inlet and exhausts pipes, now I know all about annealing prior to forming, but of course the risk of the section collapsing is ever present. I've read about filling the tube with molten solder, or foundry metal, but I've just read a piece about freezing a mixture of water and detergent inside the tube and then forming the bends. Has anyone tried this method?

[mickParticipant @mick65121]

[Graham Green 3Participant @grahamgreen3]

Heard about doing it that way, but I haven't tried it yet, please do have a go and let's know how you get on.

[Steve AbbeyParticipant @steveabbey13110]

You could also try filling with sand – something as small as this may need silver sand (i.e. very fine).

[Les Jones 1Participant @lesjones1]

Hi Mick,
Do you really mean 0.25" thick ? (5/16" bore 13/16" OD)

Les.

[Brian WoodParticipant @brianwood45127]

Hello Mick,

Try pipe springs, the sort that fit over the tubing. There are also pipe benders used by plumbers for central heating installations that have bending moulds for 10, 8 and 6 mm diameter piping.

Try Screwfix or appropriate merchants. If your pipe is annealed you should be able to make 90 degree bends in one pass.

Regards Brian

[mickParticipant @mick65121]

Sorry for any confusion, typo error, wall thickness is: 0.025''. Ordinary tube benders will undoubtedly crush the section, filling the tube with sand or salt is an option, but the grains can migrate while bending leaving the bend unsupported, pipe tubes and springs are okay for ductile pipe, such as copper. There needs to be a solid but ductile medium inside the tube to support the bend while its being formed, as I'm not running to a set of hydraulic benders which would most probably stand more chance of generating the bends without crushing. I'll try the water and detergent when the time comes and report back.

[Neil WyattModerator @neilwyatt]

Try Cerrobend, or similar.

Neil

[Marcus BowmanParticipant @marcusbowman28936]

Yes; Cerrobend (now called CS Alloys Bend 158) will do the trick. I use it for bending thicker walled steel pipe, but it is easy to use and will avoid all kinking and distortion of the tube. You may still want to use a spring or a bender with formers, but the Cerrobend will still prevent damage. I use it in steel to allow bends with much tighter radii than can be achieved using a conventional former-style bender. In fact, I use the kind of bender that is normally used for flat bar or solid circular bar, and can get tight bends.

You can get small quantities on eBay. It is relatively expensive, but is designed to be re-used.

Melt it in boiling water, a bit at a time, then pour it into the tube. Let it set (doesn't take long); bend the tube, then heat the tube and the Cerrobend runs out. I run it into a tray normally used in the oven for making cupcakes, so I end up with little thick pancakes of the material, which go back into the drawer afterwards, ready for next time. You don't want a big solid lump because although it melts at a low temperature, it takes ages to metl a lump in boiling water. I dare say you could melt it with a hotter source, but the fumes are injurious, so a layer of boiling water helps keep the fumes at bay. face mask, goggles, and outdoor working are my recommendation.

Jolly handy stuff.

Marcus

[julian atkinsParticipant @julianatkins58923]

hi mick,

i have bent thin wall 5/16" dia copper tube for internal pipe in loco smokeboxes and it is extremely difficult. in subsequent locos ive gone up a size in the OD but thicker copper tube. this makes things far more manageable but requires a degree of advanced planning with connections etc. i tend to go up a size anyway on ID for the steam and exhaust circuit.

cheers,

julian

[websnailParticipant @websnail]

I understand trombone makers use frozen water, It was on the telly a couple of weeks ago.

What angle are you bending to?

Edited By websnail on 16/07/2014 22:42:04

[Bob Brown 1Participant @bobbrown1]

The way to use CS Alloys Bend 158 is here **LINK**

[mickParticipant @mick65121]

Thanks to all. A kilo of Polybend has been ordered.

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