Have tried to use the plug in chamfer program in VCrave 10 but it keeps bombing out with various errors with my system so no joy there. Had looked on the net for a cutter. The nearest I came to what I need is a 7 degrees cutter, will have to workout what the difference is in diameter between the 8 degrees and 7 degrees then go for the cutter to make the smaller holes and opening up the rest with the same cutter.