Hi, It's possible to make wire freehand, whether roughly round or square, to a diameter of circa 300 microns (0.3 mm) but 30 microns, a third of a human hair, does test credibility for that period. Once wire has been hammered square to circa 1 mm, one can proceed by stretching, compression (such as burnishing or light percussion) and annealing. Stretching leaves characteristic chevron signs that can by eliminated by compression. Constant annealing is necessary to reduce breakage of the wire. Most jeweler's dies stop at 0.15 mm for standard orders.
Hammered wire is best produced in square sections. Rounding is done at the end by hammering the corners to an octagon section and proceed from there either by fine faceting and/or rolling between flat surfaces. Hammering produces fins at the angles that tend to flake off, leaving slight irregularities in the surface, easily blended out by further hammering. In my experience flaking causes a discard rate of circa 1%.
The use of a swage block greatly helps in producing a regular section with little evidence of hammer marks as previously said in this thread.
Modern rolling mills produce a truncated square section precisely to reduce the production of fins and subsequent flaking. This phenomena, already known for hammering, may have induced the use of the truncated square section on rolling mills at an early stage of its development. It would be interesting to find out when sharp edged square section were first used as a profile on rolling mills.
The drawing bench is certainly the best tool for producing a uniform section of any profile.The advantage of a drawing bench is that the strong steady pull eliminates characteristic "snag" signs caused when an operator interrupts the pull temporarily to adjust the grip. Biringuccio illustrated several wire drawing machines in 1540 although they certainly existed well before that date.
David
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