Bending a long, thin tube

[Nick]

http://www.the-curiosity-shop.nl/itempages/others/antique%20pipe,%20iron%20churchwarden,%2018th%20century%20pipe%201.JPG

http://www.the-curiosity-shop.nl/itempages/others/antique%20pipe,%20iron%20churchwarden,%2018th%20century%20pipe%206.JPG


Yesterday I found a picture of this pipe, and it's been bothering me ever since. It's 18th century and apparently fully functional. I'm wondering how the thing was made. Could it have been cast? I don't know how they could have made the hollow stem with casting, but if it was forged, drilled, and then the knot made, how could they have prevented the bore from being closed? Unless the very small size of the hole (I'd say no more than 2mm) makes it behave differently from larger pipe? Any thoughts would be appreciated.

[Drewed]

Fill it with sand to keep the metal from collapsing.

[Don A]

Are you sure that is metal?

I have a couple clay pipes, one from an original mold, and it looks identical except for the knot.

I'm thinking a slip molded clay pipe could be formed and then knotted and then fired to give this effect.

The one I have has a ebonized finish, so it has a sort of iron grey color to it.

[Francis Trez Cole]

fill it with DRY sand and forge it down we did some great tapers using that method

[Nick]

Don, it is definitely metal.

I didn't think of sand. I imagine it would be a pain getting out of that knot, but that must be it. Francis, how do you taper it? Do you do it in swages, and add sand as the form lengthens? That would explain the taper of the stem just behind the bowl. It would also make drilling the stem much easier (assuming the piece is shaped and drilled. I can see the bowl being welded, but the stem seems too small. I may be wrong.)

[Astro_Al]

I saw 'How its Made' on TV the other day and they had a guy hand making trombones. He used ice in the pipes instead of sand - easier to fill, and much easier to clean out afterwards I guess - just don't over-freeze or it'll split.

Al.

[Drewed]

True on the ice being easier, but he was cold bending the tube. I'm not sure if you could tie that knot cold.

[pkrankow]

A piece of wire could be threaded in the cold straight tube, the piece brought to a working temperature, say a medium red, and then bent, the wire could be forcefully removed hot when the parts get to a high black heat or a dull red heat. The wire *should* survive the pull, but there is not much recourse for a broken wire. Lubricating the wire with graphite or coal dust is probably a good idea.

Thinking out loud here.

Phil

[jawno]

We use springs for bending copper tubing. The ID of the spring is just big enough the copper tube can slide inside of it. The spring is strong enough to keep the tube from kinking and collapsing because it supports it all the way around. These are long springs so they surround the tube for several inches on either side of the bend. After bending just slide the spring back off the tube and you've got a perfect bend on the copper tube. This only works for small diameters up to about 3/8" max, at least thats what sizes came in the spring kit. The more complex the bend the harder to get the spring off but I think it could be done this way.

[BIGGUNDOCTOR]

Fill it with one of the low melting temp alloys ; fusible alloy, cerro safe , etc. Bend the item cold, then warm it up to melt the alloy out. These alloys will melt from 117 - 500 degrees depending on which alloy you get. This works for cold bends, as any forging temp is far above the melting temps.