I had a polisher motor burn out on me and went to a heavy duty
grinder unit. I could not get threaded tapers to fit and only
one’s to fit the shaft are ok. About 5/8 in from the end that
goes on the shaft drill two holes at right angles to each other
and thread them. Place the taper on the shaft at the position
that you want it and scribe through the holes onto the
shaft.Centre punch the centre of the holes and drill the shaft
the diameter of the size screws that you have threaded the holes
and to a depth to where the drill starts to drill it’s full
diameter. Fit the taper to the spindle to the shaft and in a
position to see the two drilled holes. Hold in place with grub
screws (allan key type) and only long enough to go down into the
drilled hole and level with the top of outside diameter of the
The reason of two screws at right angles is so the each is a
holding force against the other. One screw would soon loosen up.
An added security would be to use some (Locktight) but should you
wish to remove it at some time you would need to heat the tapered
spindle to soften the bond between the two. The main reason for
drilling the shaft is so the the screws do not raise a burr on
the shaft and pick and seize the spindle on the shaft.
Hope this is of some help Bob.