I made a 47” Dresden plate for the center medallion for a quilt. I used Marilyn Doheny’s 9 degree ruler. It makes the Dresden with 40 blades. I am now a qualified “volcano” reducer. Lol. Evidently I have a habit of starting out just fine, but as I approach the small end, I tend to move away from the 1/4” seam, which created the “volcano” in the middle. Now that I am aware of this, I draw my sewing lines on Dresden’s to avoid taming any other “volcano” issues.