Old skills
While I was taking my apprenticeship, a thousand years ago, we were tested in a lot fo different individual skiills. One of them was flamecutting- most people think of an acetylene torch as a cruse tool, but a skilled operator can burn a 1/4″ nut off a bolt without damaging the bolt. I can still do that, and have done so as recently as a couple months ago. The tough part is freehand torchwork- the most many people can ever do is to get two pieces of metal to separate- but if you practice you can do some pretty amazing stuff.
Our step test, at the time, was to make a 12 x 14 angle iron frame. The tolerances were a little tricky, it had to be +0-1/8″. You had to have five centerpunches on each side of the cut, and the centerpunches had to be cut exactly in half, and the centerpunches had to match when you folded the corners. The gap at the corners when folded could be no more than 1/8″.
This doesn’t sound like it would be tough, but try it sometime.
I ran across my test piece a couple weeks ago, in the basement. I don’t know if I’ve got the freehand skills for that anymore, but I damned sure did then. I remember that of 35 or 36 of us, only twelve passed right out of the gate, and only two of us did it on our first try.
At the time we were also taking a math course and a metalurgy class. I remember doing sectional etchings so we could see electromicrographs of the hardness of the materials and how the differential temper caused stress internal to the material. Internal stresses in metals can cause catastrophic failure if the stress cannot be relieved. Prince Rupert’s Drops are pieces of glass in which the internal stresses cannot be relieved.
The glass has incredible impact resistance but if you snip it’s tail, as show in the video, the internal stresses are relieved. Similar things can occur in metals, especially small pieces of steel or other alloys that have been treated for hardness but not adequately tempered- the proper application of heat will draw the brittleness out of steel.
Anyway. I was in my early twenties when I took that apprenticeship. Now those skills are old enough to drive, drink, vote, and hold public office. They may not be as good as they once were, but they’re still there, the knowledge of metallurgy has if anything improved, and I wonder, where does all that knowledge go when I die?
