I started my machinist apprenticeship in 1964, worked in that shop for seven years running things up to 5" bar G&L boring mills 87" swing lathe, universal cyl. grinder 16X72 big surface grinder, vertical boring mills, all common machine tools, then worked for a refrigeration shop doing industrial refrig (ammonia ) work and machine work, then started my own machine shop with over 4,000 sq ft of space full of standard machine tools, much like the machinery that I trained on until I retired about 10 years ago, at home I have some of the same machines, as listed below. I also have done considerable scraping and rebuilding and considerable wood patternmaking for my own and other's projects, including making replacement parts for the winches on a steam donkey at a steam sawmill that I volunteer at, where I mostly run the engines that power it; Google "Sturgeon's Mill" and see pictures and videos. In my shop we did repair work and made a line of products to serve the wine industry. The shop I apprenticed was Kaiser Steel in Napa Cal. it is all gone now but was a large fabricating operation that built small ships during WW2, and later a bunch of barges, bridges, cranes for their steel mill, pipe mill machinery for large diameter oil and gas transmission, built pipe mills for UK, Germany Japan, and others and did all the framing for the Transamerica building in San Francisco. A pipe mill for up to 48" diameter 15/16" wall welded steel pipe 40 feet lengths was also part of the operation, as was a mill to make steel tunnel liner segments for the BART rapid transit in the SF Bay area.
As you know precise alignment is quite important especially in large machine tools, the G&L boring mills needed to be leveled quite closely, these had feet of vertical travel I had to relevel one that spent a lot of time on, and used a .0005 level to do it, to perhaps only one graduation or less, it is surprising how flexible such big machines can be and how little pressure on a wrench can send the bubble scooting along.
