Replies

1. 
   USAnigel | Jul 13, 2004 01:21pm | #1

   Couple of ways. If you are trying to make a smooth curve and need to plot a line to follow I have foudn Coraldraw to be very useful. Get the two year old version for real cheap 'cause elispes and arches are easy to do, you might have to tape a few sheets together but it works.

   Free hand drawing, only draw half and then flip over the drawing and copy.

2. 
   TomT226 | Jul 13, 2004 02:03pm | #2

   .0175XR(radius of the arch)X Angle.

   Example: Arch is 3.5' wide, and it runs from one jamb to the other,

   .01745 X 3.5 X 180=11.03' for the "arc."

3. 
   Fonzie | Jul 13, 2004 03:28pm | #3

   You probably know this, but it's basic geometry that if you mark the two outside ends of the arc and the high point, the center point of the circle you are wanting to make use of can easily be found.

   Simply draw a line from the left point of the arc to the top point.  Do the same on the right side. 

   Go to the center of the left line and draw a line through this center point at a right angle to it.  Do the same on the right side.

   Where these two lines intersect is the center point of the circle. 

   Tradesman

4. 
   TheOldCynic | Jul 13, 2004 06:19pm | #4

   Just do it the old boat-builder's way:

   Drive a finish nail (or other small nail) half-way in at each end of the arch and at the center / high point.   Lay a strip of wood - strapping, ply, whatever - on one side so it touches both the end nail and the center one, do the same on the other side, and tack / nail / screw both together so the angle doesn't change.  Then place the point of your pencil in the inside of the "vee" and slide the whole contraption along from nail to nail, keeping the wooden strips in contact with the nails

   And there ya go - No triggernometry, streatching string, and no trying to tack up an anchor point for your radius

   Doc - The Old Cynic