Robin,

That is excellent, when I stop laughing and the tears have cleared, I'll see if I can find how many fat blokes can stand on the average cutter, should be an interesting Google!

Now looking at Irving's stepper motor tutorial, will then see if I can estimate the mass of my machine components and see where I go from there. Since I'm quite a bit heavier than a BS Fatbloke I keep thinking I could snap (or at least bend) most things that will fit in a Kress collet!

Do we have shear force tables for typical cutters anywhere? Is it a common figure maufacturers supply? or do we just go by Dia of the cutter and its material spec?

I'm guessing snapping during plunging is much less of an issue as the material is in compression. So am I right in thinking that as long as the shear force for a cutter is not exceeded things should be OK?

Cheers,
Geoff.