Face Form Angle - Standard Tool

Face Form Angle is the same as the Bow Angle of a spectacle frame front. herewith I wish to share to basic methods.

Suggested method by ophthalmic lens manufacturers, using standard tools.

Frame Front Reference

1. Place the frame with the top rim of the frame touching the tool's table, as that shown in the picture.
2. Ensure the left bridge/rim joint is position on the little black dot somewhere in the middle of the tool.
3. Whilst keeping the left bridge/rim joint in that position, adjust the right rim so that the nasal and temporal end of the rim are position on any and the same broken lines.
4. Now move the lever on your right side so that the line in the middle of the lever meets the temporal end of the left rim.
5. The number indicated by that line on the tool is the Face Form Angle.