JCC, In general principle you install a guide bushing in your router's base plate and it follows along the edge of a pattern so your bit is guided to create a cut. It is also possible to mount a guide bushing in many of the router mounting plates and perform the same operation from the bottom of your work when table mounted routing. The size of your pattern and the relationship of the guide bushings OD and bit diameter are not too difficult to figure out. Do you have a specific question about a router you own or a project you would like to make?
Dovetails are cut following a one sided pattern with a guide bushing; signs are made with internal templates being followed by a guide bushing. Outside shapes are cut to match a pattern by following it with a guide bushing.
Dovetails are cut following a one sided pattern with a guide bushing; signs are made with internal templates being followed by a guide bushing. Outside shapes are cut to match a pattern by following it with a guide bushing.