Basically you want to cut a thread, right? Using a 4th axis on a 3 axis mill, right? You need start angle and pitch and total length. If your total length is -565 and your pitch is 8.5 and your start angle is 0 and Z zero center of part, your start point is X0. Z135. A0. and your finish point is X-565. Z135. A23929.4124. X advances 8.5 per revolution. It takes 66.47059 revolutions to travel 565. 66.47059 times 360 degrees is 23929.4124. Does your A axis have travel/max angle limits?