# Woods metal use



## deverett (Nov 22, 2008)

I have a piece of 5/16" thin wall brass tubing about 12" long that I need to bend 90 degrees close to one end. I thought of filling the tube with Woods metal/Cerrobond to make the bend.

I could use a tube bender, but knowing my luck something is bound to go wrong and I'll end up with a flat or kink at the bend. I only have enough tube for one go at the job. So my plan is to anneal the tube, fill with Woods metal first then use a tube bender.

Question: How best to fill the tube with the molten metal?

Dave
The Emerald Isle


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## Brian Rupnow (Nov 22, 2008)

What exactly is "Woods Metal"?? Is it a true metal, or is it an epoxy with metal filings in it. If its an epoxy--it isn't going to work. If it truly is a metal with a low melting point, plug one end, and fill the whole tube. use a funnel. Let it solidify, make your bend, melt it out.--Sounds easy if you say it fast----


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## tel (Nov 22, 2008)

http://en.wikipedia.org/wiki/Wood%27s_metal


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## Maryak (Nov 22, 2008)

Dave,

Best thing I know for copper or brass tube is resin.

At a pinch dry fine sand.

Then the tube bender.

Best Regards
Bob


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## spuddevans (Nov 22, 2008)

I've heard that some folk use salt, just the regular, ground, table salt. 

I haven't tried it myself though so no warrenties with this one, and as always remember that your home is at risk if you leave the door open.



Tim


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## wareagle (Nov 22, 2008)

In the plans for the Pip three cylinder radial, the manifolds are bent after annealing and being filled with Cerro-Bend 158, which is a low melting point alloy. I haven't tried this method, but I am sure it would work. I have done the bending with fine sand in thin walled tubing (1/2") before and had decent results. 

Hope this helps.


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## stevehuckss396 (Nov 22, 2008)

Never tried it but i know this guy that knows a guy that did it.

Drill a hole into a piece of wood deep enough so the tube will stand up. Place the tubing into the wood. Pour the hot metal in with a mini funnel that you will have to make.


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## deverett (Nov 22, 2008)

stevehuckss396  said:
			
		

> Never tried it but i know this guy that knows a guy that did it.
> 
> Drill a hole into a piece of wood deep enough so the tube will stand up. Place the tubing into the wood. Pour the hot metal in with a mini funnel that you will have to make.



Thanks, Steve (and of course, all the others who replied).

Looks like I need to make a funnel with a smaller than 5/16" outlet. Having obtained some Woods metal, I wanted to use it. So guess what next week's project is going to be?!

I have heard of sand being used; salt is a new one, probably better than sand in the smaller sizes.

Dave
The Emerald Isle


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## PTsideshow (Nov 22, 2008)

Horn repair people musical kind fill the tube with water and then freeze it. 
the salt works well as the crystals are a cube shape so they slide along one another.
The woods metal is now consider toxic because of the cadmium it contains. MC Masters-Carr has a lot of low temp alloys under casting you better be sitting down when you read the prices. As some of them are pricey.
https://www.micromark.com/ sells some of the cheaper versions.
glen


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## ghart3 (Nov 22, 2008)

Dave,

First you might want to anneal the bend area if you haven't all ready. Just heat till you see the brass turn a little red in poor lighting, then dunk in water. Then run some oil thru inside of tubing so there will be no sticking of the melted metal (tinning) to inside of your tube.

5/16 you might be able to pour in. On 1/4" and smaller tubing have had good luck melting Cerrobend in pan with water. The water on top of the Cerrobend helps keep the metal clean. Attach a clear plastic tube to end of tube your not bending.  Using a suction bulb, something like the wife's turkey baster hooked on one end of tubing and the other end stuck in pan towards bottom where the melted metal is.
Squeeze air out of suction bulb and place other end in the molten metal and draw metal up.

The quicker your metal freezes in the tube the better the metal will be for bending.

gary

1/8" copper tubing


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## shred (Nov 23, 2008)

Has anybody tried the hot-water-melting plastic pellets to see how they do for bending filler?


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## PTsideshow (Nov 23, 2008)

They wouldn't be good for small bore tubing, because the nature of the beast. Plus they would require some form of follower to remove the residue, after the bend I have never taken it to a temp that is near liquid, But being a thermo set plastic I think you would have a problem with it making a mess rather than flowing out. There are numerous types of plastic compounds used in the craft area's that are wax like for mold making.

Will have to hunt up the name as the block I have left has no paperwork,any more. It is called flexwax, since it can be brushed on or poured the only problem would be though much residue is left when you melt it out.
glen


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## compound driver 2 (Nov 23, 2008)

Silver sand bone dry anneal the tube with the sand in it a few times whilst bending.
Salt can corrode the brass, its Ok on SS tube.

For 5/16th thin wall brass id go with a machined form rather than pipe benders. Machine the forms to a couple of thou over the pipe diameter.


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## Bernd (Nov 23, 2008)

I'd try plain old soft solder. Might want to add a bit of flux in the tube to make it flow better.

Bernd


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## PTsideshow (Nov 24, 2008)

http://www.amaco.com/prod-amaco-flexwax-354.html

Here is the web page for the flexwax and their other mold products.
glen


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## Bluechip (Nov 24, 2008)

Hi Folks

Of absolutely no relevance to 5/16" OD tube, but I've used Bowden Cable on small bore copper tube. In case it goes by different names elsewhere in the world, it's motor cycle control cable. Should be able to get a selection from a bike breaker for nowt. They're of no value if knackered, so you should look to pay precisely that ;D

Dave.


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