Thanx guys

The Stewmac fret calculator gives the imperial positions to 3 decimal places, so I willl just go with that. I have already created a cut image ready to convert to file.It's a bass scale, so the frets are spread further apart than a 6 string. I think that affords a greater margin. As for using pine, umm... no. I will be doing test pieces with ironbarkto get the settings right. The 0.58mm fret slotting bit was expensive and I was able to get 10 x 0.5mm bits for about half the price, so I can afford to sacrifice a few of those. I have some Indian rosewood coming, since I couldn't get bubinga...won't wast that till I get it working on something slightly harder.