It’s a GAMN’saw chain sharpener. I just watched a you tube vid on it. One of my firewood customers gave it to me yesterday to hang up in the ManShed. He found it in his dad's garage before they sold the house. Anybody ever seen one?
I still have dad's and used it exclusively up until 2 years ago. Worked great until the hole that the burr goes in finally wore enough to where the burr would wobble and not cut consistent. I had always thot about having it drilled out and putting a sleeve in it, but great tool if ya decide to use it
I had a Timberline for a lotta years, they work great. Recently moved it along since I square grind. I have seen the Gamn before over on AS years ago.
Since I'm pushing the 60 mark, I guess I fit in the "old school" crowd. I still have Dads old Granberg File N Joint I have a Timberline, it only comes out if I really mess up a chain.