Bending narrow brass tubing

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Title: Bending narrow brass tubing?
Post by: Tinkergirl on February 25, 2007, 03:45:01 PM

I have just got myself some rather narrow brass tubing from B&Q (Uk) and now I'm wondering how to bend it. It's only about 4mm in diameter (0.1575", or about 1/6") and I have no pipe-bender nor bending spring. It seems like it'd be too small for pipebenders and springs anyway.

Any suggestions?


Title: Re: Bending narrow brass tubing?
Post by: sidecar_jon on February 25, 2007, 03:52:43 PM

Well, it depends on the radius of the bend and just how round you want it afterwards. Either way it will be easier to bend if it in its soft state, it may well already be soft but if it isn't you need to anneal it, heat it to red hot (say on a cooker ring or with a gas torch) and dip it in cold water. Pipe can be bent well if packed very solidly with sand or filled with molten lead (which is melted out after) .

If its "micro bore" central heating pipe it will be soft already and take a good bend quite easily, do it by hand over a round object, like a paint tin.


Title: Re: Bending narrow brass tubing?
Post by: cjwalas on February 25, 2007, 05:06:05 PM

Hobby shops hereabout sell spring tube benders. These are tight spring coils wound to a specific thickness. You put the appropriate size over the tube you're bending and the coils prevent sharp bends. They work rather well as long as you don't bend too quickly.
Chris


Title: Re: Bending narrow brass tubing?
Post by: Jake of All Trades on February 25, 2007, 05:46:28 PM

I've had no luck at all with the springs. They work fine for copper, but they seem to do virtually nothing for brass. I finally got myself one of these (http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94571), and I absolutely love it! I'd also suggest that if hollowness isn't a requirement, try a brass rod instead.


Title: Re: Bending narrow brass tubing?
Post by: CapnHarlock on February 25, 2007, 05:58:26 PM

A decent (as opposed to what is in my area) hobby shop, especially one that specialized in model railroading, should have an inexpensive set of spring tubing-benders and an adjustable bending jig. The jig is a metal block with multiple holes for pins that act as fulcrum-points for bending smoother curves. This can be a lifesaver when making more than 1 of the same part.

When the tube-bending springs are unavailable, I have had some minimal success with using insulated copper wire (I have a LOT of network cable around). If you are lucky enough to find a length of wire that fits that particular piece, (or multiple strands for larger tubing) it prevents kinking and can be removed after bending (sometimes lubricants help here)

I hadn't heard of sidecar_jon's sand method, but it does sound brilliant- I suspect that might work much better than the wire idea. (Assuming that inner opening of tubing is > size of sand grains:)


Title: Re: Bending narrow brass tubing?
Post by: sidecar_jon on February 25, 2007, 06:09:37 PM



I hadn't heard of sidecar_jon's sand method, but it does sound brilliant- I suspect that might work much better than the wire idea. (Assuming that inner opening of tubing is > size of sand grains:)

you have to pack the sand very hard in the tube, works ok to support the tube, i wonder if brass tube would bend better hot though...


Title: Re: Bending narrow brass tubing?
Post by: cartertools on February 25, 2007, 06:44:20 PM

I was watching "How It's Made" last night and they showed a trombone factory. They filled the tubing with water and froze the tube prior to bending (using a lever arm bender around a form...)


Title: Re: Bending narrow brass tubing?
Post by: sidecar_jon on February 25, 2007, 06:48:03 PM

Now there's a neat trick.


Title: Re: Bending narrow brass tubing?
Post by: Fant�´mas on February 25, 2007, 11:14:11 PM

that is a cool trick...It's similar to my discovery that string could be pulled through the piping before bending to avoid kinking and then removed after, but it sounds like the ice would work better.


Title: Re: Bending narrow brass tubing?
Post by: phuphuphnik on February 26, 2007, 03:22:04 AM

I fill the tube with busmuth, it has a low melting temp. Other low temp metals work too, but can contain cadmium which is toxic.


Title: Re: Bending narrow brass tubing?
Post by: Tinker on February 26, 2007, 09:18:59 AM

Of all the things I've done to get good bends in tubing, sand works about the best. I'll cut the tube longer than I need, crimp one end tightly shut with pliers, pack sand in as tight as I can, then crimp the other end shut. Bend it how you want it, then cut it to its final length to pour the sand out. As others have mentioned too, you'll want to anneal the tubing first as well. It'll bend a lot easier that way.

Andrew the Tinker


Title: Re: Bending narrow brass tubing?
Post by: Tinkergirl on February 26, 2007, 04:24:59 PM

Thank you very much, everyone. Sand and ice are sounding the best/most accessible so far, with sand being possibly the most practical in my current situation (freezer space for a long thin object being tricky). I'll let you know how it goes!


Title: Re: Bending narrow brass tubing?
Post by: Dr von Zarkov on March 14, 2007, 12:57:04 AM

A mechanist of experience once recommended that brass & copper tubes be first filled with an alloy of low melting temperature: Wood's Metal. The added alloy is then allowed to cool and solidify. Upon completing the bend to one's satisfaction, the tube is heated and the liquid metal is permitted to flow out.

Rental shoppes in USA often offer apparatus suitable for bending tubular stock.


Title: Re: Bending narrow brass tubing?
Post by: CrabFu on March 14, 2007, 02:02:43 AM

heat it to red hot (say on a cooker ring or with a gas torch) and dip it in cold water. Pipe can be bent well if packed very solidly with sand or filled with molten lead (which is melted out after)

Yup this works well.... I do it often. Pipe needs to be really red hot, but don't melt it (I've done that too many times) After it cools, I fill it with salt (easier to find at home than sand), and tape up both ends. Even without the salt, it usually bends pretty well once it's been heated.

-Crabfu


Title: Re: Bending narrow brass tubing?
Post by: Caffeinated Gent on March 14, 2007, 02:04:28 AM

And don't forget to wear gloves! ;D


Title: Re: Bending narrow brass tubing?
Post by: CrabFu on March 14, 2007, 02:06:09 AM

And don't forget to wear gloves! ;D

AND your steampunk goggles!!

-Crabfu


Title: Re: Bending narrow brass tubing?
Post by: Datamancer on March 14, 2007, 09:01:37 AM

Have you also considered building a jig of some kind? I semi-recently did some decorative tubework to the aluminum brake lines in my truck and I layed the design out on a piece of wood, then slowly worked the design around it.

(brakelines2.jpg)
(brakelines1.jpg)

I used old scraps of "dyna-mat" (tar paper) to cushion the wood and clamp it in the vise at various stages of different twists. The tar paper squished around the tubing, holding it in place without flattening it.

Another thing that migth work is solder. It's cheap, comes in rolls, and is available in many different thicknesses to match that of your tubing. When you're done, you can melt it out by just barely touching the tubing with a flame. You could even use a can of compressed air in the final pass. Just stick the little plastic nozzle in the tube and blast out the molten solder (away from yourself!).

Good luck,
-~D~-


Title: Re: Bending narrow brass tubing?
Post by: Dr von Zarkov on March 16, 2007, 12:21:53 AM

Rose's Metal is used for filling tubes before bending, but my experience has been with Cerrobend, an alloy mentioned in a different thread: http://www.brassgoggles.co.uk/bg-forum/index.php?topic=672.0


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