A couple of years ago, I bought a large amount of train wheels and bogie frames but they didn't have the metal axles available. I made own axles by cutting 2 mm diameter metal rods. My free hand cutting wasn't all that accurate. If I was off by -2 mm, then the wheels would derail in curves and switches. I used up the first batch of bogies made. It is time to make some more. For this batch I decided to make a cutting jig out of a scrap piece of wood. I milled a 2 mm slot and it secured the piece for an accurate cut every time.