On Dec 17, 10:46 pm, ol3_m3 wrote:
ol3_m3 wrote:
Need to enlarge the bore on a pc of bronze stock fron 1/2" to 3/4" the
length of the material is a bit over 12". any suggestions on where I
can find drill bits and reamer with extra long shanks? any tips on
keeping the hole concentric to the OD?

need close tolerances, will be a sliding fit on the shaft it is to
fit over, is the stand for a precision grinder I am trying to build.-

I'd save the bronze for something else and press flanged Oilite
bushings into the ends of a steel tube. You could make a half-round
reamer out of 3/4" drill rod and pull it through, so the near end
guides the shank while you cut the far end.