Marking the Rear Edge

Now we’ll turn our attention to the rear edge of the key blank. At the rear end of the keys each octave measures only 6 ¼” [158.7mm] wide. To do this, the keys must splay inward to accommodate the smaller width of the rear edge of the keyboard. First, draw a mark on the rear edge of the keyboard blank exactly 17/32” [13.4mm] from the left edge. From this line, draw a line exactly 6 ¼” [158.7mm] to its right. Do this three more times.

Now draw a line exactly 3 3/16” [80.9mm] down from the rear edge of the key blank. Label it ‘Line NO’. Your key blank should look like the illustration below.