There, just had to get that off my chest. I have an Electronica EL400 4 axis set on my mill. I just used it to find a circle center using three points( which was handy as I had to mill two flats on the stock to get it to sit right in the vise, so I couldn't use a 4 point method) I also used it to do two different bolt circles. I used the calculator for all my math too. I had the book out, but she's so easy to use I felt silly for breaking it out. The display led me through it by the hand. Things like this make me feel better about spending Dropro's money. Disclaimer: All claims made by Basement Hack, not trained professionals or salesmen.