Our board is about 4' H x 8' W made out of 3/16" metal plate mounted on angle iron with a triangular footed base. Here's an easy way to scribe a circle through the grease or white wash on a metal pattern plate. It's used mostly for P.O.I. gun fitting but could be used to tally up density within a 30" circle if one wished to take the time.
First, drill a hole in the center of the plate area..3/8" will do. If the plate is large enough, multiple holes can be set up side to side or in four quadrants.
Using a piece of flat bar stock about 36" long (aluminum works well), drill a hole in one end and attach a pin or smooth shank bolt a shade smaller than the diameter of the center hole in the plate. The bar will rotate in a circle around this center hole with the pin holding it in place.
In the other end of the bar drill a hole and attach another pin Use a longer pin that will go through the flat bar with one end acting as a handle and the other end(pointed)acting as a scribe.
Just rotate the bar in a circular motion and you have scribed your target circle. Remove the scribe bar and use the center hole as your target within the circle.
Using a paint roller, apply grease or white wash again, insert bar and scribe a new circle and shoot. It's much quicker and easier to use than paper or cardboard once the fabrication is done!
