machining 10 inch drums

I converted my Demon's rear brakes to the larger 4 1/2 bolt pattern , too. The right way is to get the correct backing plates and all the bigger brake hardware. But I didn'do that. All my small bolt pattern brake parts were new. I found that the 1970 Ford Maverick brake droms are very similar inside and width. The only thing that I had to do was to bore the center to fit my Moser axles. Put them in the lathe backwards so you can indicate off the bigger bore. You my want to use a face plate with a 4 inch or so hole instead of trying to chuck them.