Greetings, Lee's "Sharpening" has a jig for setting blade projection for the Eclipse honing guide. I'm making one. The objective is to easily set the guide for bevel angles other than the standard 25 and 30 degrees. In order to place the pegs, I had to do the trig. Turns out that although the imprinted instructions are in millimeters, the device (mine, anyway) was manufactured in inches. Having been through the trig, and discovering that one doesn't have to account for the changing tangent of the surface to the roller (sigh of relief), I asked my spreadsheet to make a list of projections for various bevel angles. I post it here for y'all to file and forget. Someday, someone will google for the info, and here it'll be. Note that the values in the imprinted instructions differ from my analytical values. The table is free; so what if no one will need some of the extreme angles!
Bevel, degrees Chisel Projection, mm Iron projection, mm
15 83.8 104.6
16 77.0 96.4
17 71.0 89.2
18 65.7 82.8
19 60.8 77.0
20 56.5 71.8
21 52.5 67.0
22 48.9 62.7
23 45.6 58.7
24 42.6 55.0
25 39.7 51.6
26 37.1 48.5
27 34.7 45.6
28 32.4 42.9
29 30.3 40.3
30 28.3 37.9
31 26.4 35.6
32 24.6 33.5
33 22.9 31.5
34 21.3 29.6
35 19.8 27.8
36 18.4 26.0
37 17.0 24.4
38 15.7 22.8
39 14.5 21.3
40 13.3 19.9
41 12.1 18.5
42 11.0 17.2
43 9.9 15.9
44 8.9 14.7
45 7.9 13.5