Just wanted to post this.I have a member who has been P/Ming me about this problem.He has a oversize Gretsch shell and does not want to re-cut the edges after a re=wrap.Two ways to do this.First if the wrap is on the drum mark the wrap at the edge around the drum,If no wrap is on the drum you can still mark the shell say 1/2" or less down from edge mark it at 3,6,9,12 and take a old drum head rim _with the head cut out of it- place the rim on the shell line it up with the marks at 3,6,9,12 and mark around the drum...Mikey