snip
That's pretty much what I figured: It doesn't work and now I know it
can't. Thanks! I'll start checking out Enco. Do you have a URL for them,
perhaps?
In addition to msc/enco [actually different sided of the same
company see:
http://phase2plus.com/details.asp?pr=R-8_COLLETS&id=17
http://phase2plus.com/details.asp?pr...-8_SHANK&id=29
[fwit -- I find the holders are better than the collets but
cut-down on the headroom.

http://www.wttool.com/c/17000010p
3/8 collet c.6$US
http://littlemachineshop.com/product...ProductID=1604
[set of 6 c. 24$US]

https://www.travers.com/pdfshow.asp?p=496
http://www.wttool.com/p/1617-9910
Spring collet to R8 adapter -- good if you change tools
frequently]

http://www.wttool.com/p/0958-9901
6 3/8 shank endmills and a 3/8 R8 holder 30$US
http://www.wttool.com/c/16169980p
full set of holders

One trick is to get a 1 inch R8 holder and make up adapters for
your smaller tooling from 1 inch drill rod. Quick change tooling
cheap.

Uncle George