I have an old super tigre2000 that a guy gave me because the crank was bent.It uses the collet idea.I straighned the crank most of the way by putting it my vise,straighten some,in lathe,in vise,in lathe,ect.. unitl it was almost perfect.Then put it in lathe and tapped it while it was turning around slowly.And yes i used a rubber mallet and tapped it very gently as to not bother my lathe.Its straight and true with no runout.