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Router guide bushing calculator

1

Your tools

Standalone guide bush in green outline, with the outside diameter of its smooth guide collar marked GUIDE OUTSIDE DIAMETER
Two-flute straight router bit with its cutting diameter marked CUTTING DIAMETER

Decimals and fractions are accepted: 19.05, 3/4 or 1 3/16.

2

Template

Template routing path
3

Dimensions

Calculation direction
Finished size
Template size

Template size

Inside template

114 ×44mm

4.488 × 1.732 in

7 mmoffset per edge
Template and routed cut diagram Top view showing the template opening, finished cut, guide bushing and cutter. Template edge Finished cut Bushing Cutter Offset per edge Length Width
TemplateFinished cut
Calculation

Offset = (20 mm − 6 mm) ÷ 2 = 7 mm

Total size difference: 14 mm

For an inside template, add twice the offset to both finished dimensions.