X-Mozilla-Keys:                                                                                 
Gary Wolf wrote:

Vance,
   At the risk of being considered a heretic, I would like to say something
nice about welded tube as well. All of the frames I have seen are made from
it and the weld never breaks either.

   With welded tube the wall thickness is the same at all points. Seamless
tube, because of the process by which it is made, cannot be guaranteed to be
concentric, and allowance must be made for the thinnest area of the
perimeter. The thin spot seems to move in a spiral down the length of the
tube. Babcock and Wilcox, the people who brought you Three Mile Island, is a
block from my shop and the fellows there who do tube bending are masters at
it. They saw apart samples of tube from each batch to map the location of
the thin areas and then decide how to set up for bending to minimize
thinning at the outsides of all bends.

   This varying wall,and the price, is why DOM is taking over the seamless
market. DOM is basically welded tube that has undergone a bunch of
subsequent drawing and annealing processes until it is impossible to find
the weld.

   The Brits favoured the nickel bronze method because labour was cheap in
England back in the fifties, and Tig welders were not. Their pride in
craftmanship was necessary to ensure a rigorous attention to the welding
process to ensure a good bond. The Brits had it then, but now they are the
same as us. With the nickel bronze, any two guys working in a cold garage
could take on Ferrari and the world in formula car construction, while
living on an income of 8 pounds ($20) per week.
                                                Gary Wolf

 
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