12-12-2014, 02:50 PM
If you already have round plates to start with, I'd trepan on the lathe this way:
Face one side clean. Using a trepanning tool, plunge a face groove to 1/2 the depth of the thickness. Be exact about how far in you actually go. Flip the part in the chuck, clean the other face. Measure thickness, then plunge a trepan tool to within .005" to .010" of the face groove on the back. Do NOT break through with the lathe spinning as you don't want a kg of sharp edged aluminum disk shooting at you.
Remove from chuck, give the center section a good whack with a soft face hammer being careful t catch it with a leather of other protective glove. Now you have a usable slug.
Face one side clean. Using a trepanning tool, plunge a face groove to 1/2 the depth of the thickness. Be exact about how far in you actually go. Flip the part in the chuck, clean the other face. Measure thickness, then plunge a trepan tool to within .005" to .010" of the face groove on the back. Do NOT break through with the lathe spinning as you don't want a kg of sharp edged aluminum disk shooting at you.
Remove from chuck, give the center section a good whack with a soft face hammer being careful t catch it with a leather of other protective glove. Now you have a usable slug.