BT30 in an R8 spindle?

[spluppit]

Ross, I need to eat a bit of humble pie in a way. I have both tapers at my works and tested your idea. Much to my surprise the actual taper appears to be the same and the and it fits in a R8, and sits pretty well with not a lot of overhang. There is a slight problem with the top part of the taper sitting in mid air, this does give a small amount of play which will mean run-out to some degree. A R8 collet has a parallel section at the top which is a fit in the spindle and ensure the taper is sitting correctly. So this is the part you need to be wary of. I still wont suggest you do it as its not perfect and obviously its not designed to be used this way, but at least you have the pros and cons now.

I understand you don't want to spend money on new gear with only a little work to do but R8 cheapo spring collet (which are perfectly adequate by the way for general work) are very cheap and always preferred over an er collect system for rigidity. worth a thought as they don't cost much at all these days.

All the best