Re: Hardness of M2 HSS drill rod?
Typically for a dowel pin you want +0.000 to -0.0005 for the tight side, and for a slip fit on the mating part you want +0.0005 to +.003 or so depending on the required fit.
I normally do this with reamers. I guess I would buy the reamers to do the job properly, it's pretty hard to interpolate a dowel pin hole on a CNC mill, especially if you don't have pin gauges to test. The other option is to buy a set of small hole gauges, that will get you pretty close.
Jim Dawson
Sandy, Oregon, USA