Tuesday, May 01, 2007

Early Pattern Welding Experiments

Published Methods on Pattern Welding - Are they ACCURATE?

> ... the experiments that
> were done at the Museum of The English Rural Life in Reading England. I
> estimate that somewhere in the 1960's a group tried to duplicate several
> patterns found on sword blades. ...
> They found hat if common bars (flat or rectangular) or rods (round) are
> twisted there are gaps in the core of the finished bar. They had better
> results, with both quality if the finished bar and duplication of existing
> patterns, when they placed a rectangular bar between two rods and twisted
> the bundle. The rods would fill in the gaps of the spiral bar for a tighter
> bundle. ...
- 'Carl'

I saw some second hand references to that work when I first starting smithing in the late 70's. Through one of those Serendipity Effects, I had someone show me one of the original reports at a symposium in April. You will also find those methods illustrated in any number more popular books from the mid 70's through - even up to the modern day. (A wonderful example of bad information retained in academic writing. The classic 'Vikings' by shows this suggested process and has been widely copied)

The problem is that the method as described is just not effective.

Any use of round rods in a bundle creates two major problems. First is the very real problem of compressing anything that is made of a number of round cross sections - they just get shoved to one side. One way to solve this is using a half round bottom tool. Often seen in historic shops for making tendons for joints. Taking round rods and twisting them into a bundle will also help solve this somewhat - but accents the second problem.
The second is the gaps left with round sections in a bundle. With any number of rods more than two - there is a large space between them. This would be minimized by use of a bundle of six or seven - which would have one rod in the middle surrounded by a group that just touched around the inside. Use of round rods further creates a large number of V gaps around the outside edges. All of these spaces tend to generate welding flaws, resulting in cracks around the outside surfaces.
A further consideration is that in ancient times raw metal was purchased as short lengths of roughly square 'currency bar'. The wrought iron would have to be hammered out to create those round rods in the first place. (For that reason round profile is rarely seen in pre-industrial objects, unless a specific point about elaborate effort is being made. The cauldron hanger from Sutton Hoo a perfect example.)

I also strongly suspect that the pattern that would be generated from such a method (twisted bundle of round rods) would not give the same physical appearance to the finished object. This strongly indicates an experimental archaeology project!

I've got a new digital camcorder coming in a couple of days. I do want to resume the (so far failed) project to film 'Introduction to Layered Steels', and may include a segment showing the (incorrect) use of round rods. At the very least, its worth making up some test bars and recording still images of the results.


1 comment:

STAG said...

What would the results look like if you twisted a group of iron bars into a rope and set it in a pot of molten steel? The steel has a lower melting point than the iron.
Just wondering if you could pattern weld without a hammer.....

Just a dim memory coming out about Pakistan hill-side founderies. I know they did layers of plates, but I wonder if they did "ropes". Like how could you tell?


February 15 - May 15, 2012 : Supported by a Crafts Projects - Creation and Development Grant

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