I have just tried the HSMadvisor free calculator and like it, easy to use. The G-wizard calculator is too expensive for all that I would use it. Anyway where are you buying your single flute carbide bits from? I have been buying from aliexpress.com and am beginning to think I should buy some better quality bits. the bits I have been using were listed as suitable for cutting acrylic, organic board material, Metal, Copper, Aluminium, but I have my doubts now.