This is a PDF scan of the Dumore series 11 Tool Post Grinder.  The last page is a scan with dimensions of the collet adapter for 1/8" shaft mounted stones for inside grinding.  The inside threads are 1/4 32 and the outside threads are 5/16 32.  The ID is counterbored to mate with the sholder of the spindle.

Glenn Neff
Medford, OR
sleykin@charter.net