With profiled router bits such as our 15° Dovetail router bit, it can sometimes be confusing as to which values you need to use. We have therefore summarized a few dimensions and specifications that can make your work easier.
If you want to achieve a perfect fit of two parts  for example for burr strips  and use the same contour (one internal and one external routing), you must observe the offset (b) for one of the two cuts. This results from the lateral widening, which changes depending on the plunge depth.
Offset when cutting the same contour inside and outside (approx. 10mm cutting depth)  The lower the cutting depth, the lower the offset. (approx. 5mm immersion depth)  Offset b for a contour, for a perfect fit (approx. 5mm immersion depth) 
Equation for calculating the offset
Our Dovetail router bit has a cutting edge length of 13.5 mm and an angle of 15°. The following equation can be used to calculate the offset (b) as a function of the plunge depth (a):
b= tan (15°)*a
The tangent tan (15°) results from the angle of 15°. You can replace this for other cutters. Suitable tables with the values for the tangent can be found on the Internet.
Example for a cutting depth of 10 mm
b= tan (15°)×10
b= 0,2679×10
b= 2,679
Offset table as a function of the plunge depth (for the Shaper 15° Dovetail router bit)
Depth (mm) 
Offset b, rounded (mm)

1  0,27 
2  0,54 
3  0,8 
4  1,07 
5  1,34 
6  1,61 
7  1,88 
8  2,14 
9  2,41 
10  2,68 
11  2,95 
12  3,22 
13  3,48 
13,5  3,61 