Blacksmithing...tales

[pkrankow]

Terry,
I love your articles. The only thing that struck as off (not wrong) is the mach 1 O2, that is only a function of the nozzle. For a given change of pressure, the speed of sound through the orifice at the lower pressure is the limit of the mass flow rate. Even your tire when you let air out has supersonic flow (it is loud). Having less velocity than mach 1 means that more flow could be put through it. Having more velocity than mach 1 means it has been accelerated by the shape of the nozzle. The mass flow rate however has been limited by the earlier cross-section. This is true for all gasses as long as the starting pressure is above the required pressure for supersonic flow in that medium.

I really enjoyed your articles as they bring together many things family members have done in Cleveland Ohio and elsewhere. My Dad (in his younger years) had a job where he cut the rollers for the steel mills, one pass on one roller would take a full 8 hour shift or more. One roller might take over a week of shifts (3 per day) to cut. Defects would be welded by a master welder and then re-cut by the lathe operator. They would also cook coffee and lunches using the hot ingots cooling in the yard as stoves.

My cousin worked for a company that made massive forging presses (Ajax). I worked with him for a summer as an internship, I did inspection and learned from all who would teach. Heck the inspection specialist took a vacation leaving me in charge even! I could read a print and use a micrometer, even one over 3 feet across. That caused some bumps as I failed a bunch of stuff, and nobody took me seriously till I explained all the failures individually (most were easily correctable).

Another cousin was a chemist in the mills, and would pull and test samples of molten steel in the Lorain Ohio mill. My brother held a job servicing the X-ray and radioactive measuring devices used on modern mills. He even helped (re)develop a low tech air gate sensor to tell if metal was present, saving use of an x-ray device.

I have had not read a series of accounts that describe the separate experiences I have been related as a whole. I did find it very enjoyable and entertaining.

Thank you for taking the time.

Phil