What angles do 1:6, 1:7, 1:8 correspond to?
Dovetails angles are often specified as a Rise:Run ratio, for example 1:7. This corresponds to the angle of a line that covers a vertical distance of 7 cm (or inches, or whatever unit you prefer) and deflects horizontally by 1 cm (or inches, or whatever unit you prefer).
Here are the angles that these rise:run ratios correspond to:
In case you are wondering, the formula to calculate the angle from a rise:run ratio is this:
If you want to do this in a spreadsheet, use this:
And here’s the opposite table from a few suitable angles to the corresponding rise:run, if you were wondering:
The formula to go from an angle to Rise:Run is this:
Rise = 1 Run = 1/tan(angle)
In case you are wondering what “the correct” angle is - there is no consensus whatsoever. Answers vary greatly depending on who you ask, but everything I have ever seen is between 1:4 (about 14 degrees) and 1:8 (about 7 degrees).