ONE INCH! You showoffs kill me. You guys do some amazing stuff. I can almost cut a straight line.
The "customer" was right there helping, so I didn't have time to practice. ...It was just a friend from work. They were letters for his daughter's graduation party.
Well, now we know. A #1 forwards seemed to work well on 2" foam. If the foam had been thinner running the blade backwards might have worked. I was afraid the blade would get too hot on the 2" and would start melting the foam badly. For the short test cuts it left a really smooth/melted edge, but it was already getting a bit warm. Larger teeth didn't do well, so the smaller the better. I had some 2/0 spirals, but didn't try them. I could almost cut sideways without turning the foam as it was. I could cut a straight line without angling the foam. That threw me for a bit. Results below. Thanks for the input!
Bob