Bending brass K&S tubes - RC Groups
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Feb 11, 2010, 09:58 PM
apprentice shipwright
John Pilot's Avatar

Bending brass K&S tubes

I'm in need of some expert advice on bending brass tubes . Diameters about 1/8" - 3/8". Bend radius I'm trying to achieve is about 2x to 3x tube diameter. Tried filling tubes with salt etc, tried heating them, but so far no luck getting decent bends.
I'm sure someone out there has this down to a science and is willing to share their knowledge.

Thanks in advance.
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Feb 11, 2010, 10:06 PM
Nickel Belter
ZZ56's Avatar
I saw on TV that trombone and trumpet makers put a soap and water solution in brass tubes and freeze them solid before bending. The soap keeps the ice from shattering.
Feb 11, 2010, 10:11 PM
Taking care of the pond.
I got one of these, works good.
Dubro 1/8" Tubing Bender
Feb 11, 2010, 11:03 PM
Grumpa Tom
Kmot's Avatar
You must anneal the brass tube first. Then pack it with salt, not loose but packed. Then crimp the ends so it cannot escape. Now, using a tube bending mandrel, make your bends. 2x and 3x tube diameter is an extremely tight radius. The Dubro benders cannot go that tight. A mandrel like the Higley is better for tight radii.
Feb 12, 2010, 07:20 AM
"day ain't over yet-"
der kapitan's Avatar
And again- I've mentioned this before, K&S makes malleable tubing that will work well for motor casings. I don't know about the small diameters that John Pilot is shooting for, but I'd have to say LOL---.
Feb 12, 2010, 10:49 AM
Registered User

Dowel Works

John, I used a wooden dowel with a 1/8" groove filed into it. It makes clean radius without crimping, bending, or collapsing the K&S tubing. My son-in-law (professional mechanic and not a model builder) "invented" the device when I whined about the trouble I was having. A picture is on page 6 of my build thread titled "F-31 Trojan Modification". After the grooved dowel solved the collapse/crimp problems, I had trouble getting the correct lengths for the multiple bends, so I added a Rube Goldberg guide for making a square structure with 90 degree bends. Hope this will help you.

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