I am now making a new set of blanks for my cutters, this time trying my best to get all the tooling as accurately set up as possible.
First off is the drilling of the positioning holes. To do this I mounted my ER32 chuck directly onto my rotary table rather than onto a chuck adapter fixed to the table (to cut out as many "middlemen" as possible. I had to make a new set of T-bolts with 1/4" BSF threads to do this. The chuck was carefully positioned using a gauge held in the spindle and repeated taps from a hide mallet until everything was true. The arbor was then held in a collet. All went well and the set of five holes was nicely concentric (better than before).
Next was to mount the ER32 chuck accurately in the lathe. I had tried this before but was never happy with the result. The ER32 chuck was sold with an adaptor for the Myford lathe which screws on to the lathe spindle. The chuck is then fixed on, the location being by means of a close fitting male part on the adaptor locating in a female part on the chuck, with three screws to hold it in place. Despite following the manufacturers' instructions and turning the male part in situ to ensure concentricity with the lathe I could never get the chuck itself fully concentric so I have now tried an alternative, which is to make the whole thing a somewhat loose fit on the adaptor, including opening up the countersink holes for the socket screws a shade to allow a little more movement, then tightening it down gradually with a dial indicator in place, tapping with a mallet until it is aligned. This finally seems to have worked, the eccentric mandrel has been mounted and trued up and the next stage of cutting the relief edges is underway.
First off is the drilling of the positioning holes. To do this I mounted my ER32 chuck directly onto my rotary table rather than onto a chuck adapter fixed to the table (to cut out as many "middlemen" as possible. I had to make a new set of T-bolts with 1/4" BSF threads to do this. The chuck was carefully positioned using a gauge held in the spindle and repeated taps from a hide mallet until everything was true. The arbor was then held in a collet. All went well and the set of five holes was nicely concentric (better than before).

Next was to mount the ER32 chuck accurately in the lathe. I had tried this before but was never happy with the result. The ER32 chuck was sold with an adaptor for the Myford lathe which screws on to the lathe spindle. The chuck is then fixed on, the location being by means of a close fitting male part on the adaptor locating in a female part on the chuck, with three screws to hold it in place. Despite following the manufacturers' instructions and turning the male part in situ to ensure concentricity with the lathe I could never get the chuck itself fully concentric so I have now tried an alternative, which is to make the whole thing a somewhat loose fit on the adaptor, including opening up the countersink holes for the socket screws a shade to allow a little more movement, then tightening it down gradually with a dial indicator in place, tapping with a mallet until it is aligned. This finally seems to have worked, the eccentric mandrel has been mounted and trued up and the next stage of cutting the relief edges is underway.

