richard.. i took a look at the blueprints, and there is a small chance i am wrong here, but i doubt it. the angles are measured acording to a 90 degree cut. a normal stock at the measured angle is 90 degrees. if you were making the angle cut in the opposite direction, the angle would read less than 90 degrees, but in these plans, the measured angle is greater than 90 degrees. so, to find your angle, subtract 90 from 108. your angle is 18 degrees. subtract 112.5 minus 90, your angle is 22.5 degrees. as for the radius, you will need a somewhat large workspace to line the mark up. put the workpiece down and measure off a piece of sting about 48-50 inches long. tie one end of the string to a pivot point, i would use a nail into a piece of board the same thickness as the piece to be marked. measure off 48inches and tape a pencil to that point. stretch the line out and make sure the workpiece is aligned so that the pencil touches both lower corners of the piece and all the slack is taken out. this will measure out the piece so that when you swing your arc across your workpiece, it will mark a curve with a 48 inch radius. its like making a big compass.. the string method will get you pretty close... the other option is to use a piece of thin scrap wood that is 48-50 inches long. hammer a nail through 1 end and into a secure piece of wood that will not move, this will be your pivot point. measure out 48 inches, mark it, then drill a hole at the 48 inch mark that will allow for a pencil to drop into the hole snuggly. this method will eliminate any slop that you would have in a string, allowing a perfect 48 inch radius curve to be drawn. hope this helps..
Last edited by mayday3374; 03-05-2008 at 09:41 PM.