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Bending rigid tubing


Curti
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Have you tried those springs that fit over the tubing so you can bend it by hand and not kink it? I have a set that I bought at Home Depot that I use for bending those small-diameter hard lines for toilet tanks and sinks that are decorative. You should be able to buy a kit that includes 4 or 5 different diameters. I don't know if you can bend it as sharply as shown in the photos, but it will work better than trying to do it by hand and not kink the tubing.

Hope this helps.

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Hi Curt,

Have you tried bending it around a pipe?

I use to fill the tubing with white playground sand, cap the ends and heat the section I want to bend. Once a nice wide section is heated, I'd hold one end tightly and wrap the tubing around the pipe. The pipe is usually mounted vertically in a vise or in some cases it was the support pipe holding the ceiling. Depends on the size of the bend. I've never tried it with brass though. How expensive it the tubing?

Let us know what works

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How about this Mcmaster-Carr product? a little pricey but something similar can be found elsewhere I'm sure.

Item # 242185, or just go to their site and search tube benders.

I'm guessing the tube is for vacuum wipers mounted in an open car? I'm about to bend the same size tube for 31 Lincoln convertible coupe.

-Tom, So cal

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Thanks for the quick replys fellas! Yes, they are vacuum supply lines for an Auburn speedster.

I went to Mcmaster, 242185 dosn't come up, the part numbers all have an alpha character.

The smallest radius is about 1/2" I think a combination of the suggestions will be in order.

sand, heat, a bolt of the radius needed clamped in a vice. and maybe the spring over it.

And Ov-Gloves so as not to burn my pinkies. I'll post the results.

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Guest De Soto Frank

A friend whose trade was repairing brass band instruments once related the trick for bending tight radius bends in brass tubing w/o kinks was to cap one end of the tube, fill it with melted pitch (pine tar or similar stuff), let it cool, then carefully bend the tubing to the desired shape ( cold ), then heat the formed piece until the pitch ran-out.

Fine sand would probably do the same thing for your project.

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Guest sscargo

It might help if you anneal the tube prior to bending. Simply heat the tube until it starts turning red and then quench in water.

TTFN

Mat

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Another technique was to fill the tubing with wood's metal, a very low heat melting alloy. After its bent, just immerse in boiling water and the filler will come out.

Interesting what is coming on this forum!

Could you please tell me more about that wood's metal? It could be the solution to fabricate the exhaust lines of my Continental scale 1:12. Don't tell me that I can buy it at this or that store, I'm located in Switzerland...

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Well, here is what worked for me:

Threaded the inside of both ends of the tubing with a #8 tap. screwed in a machine screw for a plug. This is 3/16 OD tube, the ID is ideal for light threads.

Filled the tube with beads from the beadblaster, tapped it down so as to compact it. When it is full insert the second machine screw.

Anneal the first and tighest bend. Bend ONLY with my fingers. ( I damaged one by trying to bend it over a bolt.)

Unscrew the machine screws and pour out the media.

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Guest De Soto Frank
Interesting what is coming on this forum!

Could you please tell me more about that wood's metal? It could be the solution to fabricate the exhaust lines of my Continental scale 1:12. Don't tell me that I can buy it at this or that store, I'm located in Switzerland...

Roger,

Try an internet search on "wismuth"... it involves a technique used to fill engraved lettering with metal after the surface has been painted or otherwise finished...

It was how the engraved lettering was "filled" on the top-plates of black-painted Leica cameras in the 1920's and '30s, to name one application.

Regards,

Frank

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Thank you Frank and jdome. Google had a good search result with woods metal; wismuth leaded to bismuth which is the base metal for the woods metal. I even found a store in Switzerland where I can buy it.. Not cheap, 100 grams for about $ 90.00. I will give it a try; I may use that metal for other applications for the scale model.

Everyday there is a chance to learn something!

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I've heard that musical instrument makers bend tubing by filling with water and freezing it. Having had pipes burst from freezing I'm dubious but it might be worth a try. Heating the water first to drive off dissolved gases might help...........Bob

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Guest car crank

Rotometals has the Wood's Metal for $15.99/lb about 2.5 cubic inches.

Low Melting Bismuth Based Ingot 158 ALLOY Wood's metal

I use Wood's Metal all the time for bending thin wall tubing and could always use a couple more pounds. Neat stuff, but it can be a bit persnickety. You have to soak the tube in oil so it doesn't tin the sides (brass tubing). It is also very brittle along the crystalline boundaries and if you let it cool slowly the crystals get really big (around 1/4 square), so I quench it in cold water as soon as I pour it to keep the crystals small. That keeps it from breaking and coming through the tube. I also find it is much more pliable if you soak it for 10 minutes or so in hot tap water before bending. Aside from the tinning issue, I don't think any of these are concerns if you use it for fixturing. It's really cool stuff.

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If you ever see a magician bend a metal spoon with his "mind" it is actually the heat of his fingers rubbing the spoon and melting the Cerometal spoon. Fun stuff to play with. We have used it to secure odd shaped pieces into a box so we could clamp the piece to a milling machine for milling. Expensive but it lasts forever.

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