Claydon clamp joinery

[Sprockets&Cogs]

Saw David Thompson's "Claydon clamp joinery" on the samples table at the NWBA spring conference. Any ideas how it was done? I assume the clamp is the box tube and the larger piper is used to drive over the end of the rod?
Thanks
Erick

[Mainely,Bob]

Looks like he heated the square tube in the forge,then laid it on top of one of the round elements to be joined,then put the other round element on top at a right angle and pressed or hammered straight down onto the assembly until the 2 rounds made contact.The short section of square tube crushed and distorted till it held the two rounds together.
Some preliminary forming/flaring may have been done to the square tube to lead it in the intended direction but once it started moving it would flow around and clamp the 2 rounds together.

[SoCal Dave]

Try it with some clay. See if you can duplicate it with clay and then try it with metal.

[Glenn]

Clayton clamp is done by heating a piece of pipe (or tubing) and placing one work piece below and one work piece above the pipe (perpendicular to each other) and compress. The work pieces deform both ends of the pipe simultaneously. On each end of the clamp, the pipe deforms open along the length of the work piece, but also deforms closed across the work piece. This clamps the work piece in place, and the holds two pieces together.

The sides of the clamp should extend above the center line of the work piece in order to clamp well. See attached photo.

[Bentiron1946]

Seems like I've seen this in an industrial application before, is it really just this new? Looks kinda nice, maybe use it to make a window grille or gate?

[Pat Roy]

Will it develop as a secure clamp or is this a prep for welding?

[nuge]

I remember reading that during a demo the author of the connection said he took out a patent on the design so big business would not get hold of it. He then said that smiths could use it all they want. For what it's worth.

[anvil]

I have used the claydon clamp on a few rails, and it works very well.. saw it at an ABANA conference many years ago,, Ripley, W. VA i think. I have the dimensions of the square tube on a sample piece at home, but am on a road trip. I believe the total height is a little less than ht of both round bars used. any size square tubing can be used,, depends on design. get the square bar white hot, place one round bar on your table, balance the tubing on it on its diagonal,, place the other round bar perpendicular,, hammer together, them,, most importantly, quench til cool. this last will then shrink all together.. this makes a very good and long lasting form of joinery, and is standalone.. but, you can if you want drill a hole through all, and add a rivet if you feel the need.

I think the man who demoed this was "Claydon",, an English smith,,and he said it had been used many years ago in an industrial application to make rebar mats.

anvil

[dkunkler]

It was patented in the US by Stuart A. Hill. http://www.blurringlines.com/stuart.htm
Here you can find the U.S. patent for this technique. http://patimg1.uspto.gov/.piw?docid=04631797&PageNum=1&&IDKey=C00E06F76901&HomeUrl=http://pimg-piw.uspto.gov/

[pkrankow]

a different link, the apple plugin doesn't like my computer

http://www.freepatentsonline.com/4631797.pdf
Phil