Determining the Counter Rake for Work That Lies Athwart the Plane of the Rake
1- Horizontal reference
2- Vertical reference
3- Rake (2" in 1 foot- in this example)
4- Parallel to rake line (at the width of flat)
5- Parallel to the vertical Reference (at the width of flat)
6- From the rake line at A, draw a line at the known angle athwart the rake; of sufficient length to cross 5 or 4 – This distance AB is the length of the counter rake.
7- Strike an arc of length AB from C (an arbitrary point convenient usually at 1-1/4 times the width of the flat away from A) to intersect the rake line parallel.
8- Draw the line CD from center of arc to where it intersects the parallel.
9- Erect perpendicular from center of arc to the parallel. The angle between the perpendicular and CD is the angle of the counter rake.
The angle between AB and a perpendicular to the rake line at A gives the edge bevel for the flat.
Round numbers are given for this example, however, no calculation is required. The entire procedure may be performed, and the resulting length and angles, may be obtained and transferred to the work using only a beam compass, a straightedge and a bevel gauge. The procedure may be performed at any convenient scale. Remember, however, that at 1/4" - 1'-0" scale a 1/16” pencil line is nearly 1" wide; which can affect the results.
Note: If the rake you are dealing is a compound rake use the preceding construction to obtain the “true dip” for your counter rake calculation.