I had been following Phil Kerner and his YouTube video series for about a year. His videos detailed a lots of experience regarding machining in the tool and die industry. In this industry a lot of skills and knowledge get passed down from machinist to machinist.
I am an engineer, but I think like a machinist in my designs. It makes my solutions practical and ultimately take less time and money to produce. Since taking on machining as a hobby I I found the skills valuable as they transferred directly to my career.
Phil Kerner (thetoolanddieguy.com) takes 35 years of his experience and now puts his videos on a pay version of his site. You can get an annual subscription for $48 and a “lifetime” for $68. I recommend getting the lifetime now. The information you get from this is a fraction of the cost to attend a machining course. Its high quality and he’s telling you everything you need to know in a clear and concise manner. $68 is a steal in my opinion – I don’t know how long he will keep the price as his courses are getting very popular, so I would jump on it if you think it is worth your time.