|Prior hot rolling
hammering was the technology used for shaping the iron into bars. Water
powered hammers were first introduced in the l5th century, at Karmansbo
400 years ago.
The speed of this helve hammer was 60-80 strokes per minute. The finishing
of the bar to desired dimension and surface took 1000-1500 strokes
and up to 15 minutes to make one bar. Maintenance was important as the
wear was huge and the hammer had to be operational around the clock.
Exceptional skill was required to quickly shape the iron into bars
of desired dimensions.