I have had bad experience with the old Bergeon cannon pinion tightener leading to the pinion breaking.     I have now received the Bergeon 31001 tool. If you have a jewelling set then this is certainly the inexpensive way to go. The pinion was gradually squeezed by an amount measured on the vernier until it had just a nice friction fit onto the centre arbor. This progressive approach beats all of the 'tap it with the hammer and try'  methods.