John, you mentioned a vintage Disston hand saw. There are a couple of those beauties that belonged to my Grandpa, Dad's dad, who helped build the house I grew up in nearly 75 years ago, still hanging in the garage. One of my first memories as a 4 year old was hammering nails in the subfloor of the living room with Grandpa, wearing my little tool belt that my mom made. I was looking at those Disston saws a few years back and was intrigued by what I found out was the "nail tooth" on the back side of the blade. I'm still not so sure how what they were used for - I assuming cutting the stray nail when using a saw for demolition work.
I would love to see a picture of the nail tooth. I’ve never seen anything like that before.
