I'm trying to decide how long the cutting edge on a pattern router bit should be. I'm trimming a 2-by (1-1/2" actual) with a pattern / template on top, and I'm having a hard time finding a 1-1/2" (cutting) length bit. I found a 2" length. Is there a reason I shouldn't just use the 2" length? I can't find any technical information about selecting the appropriate length, or whether I should avoid a longer length.
P.S. I'm aware of the stability considerations with shank diameter; that's not what this question is about. The 2" length bit has a 1/2" dia shank.
Best Answer
You could (and probably should) do this with a shorter bit. Unless you're just skimming off little bits to finish a cut previously made with a jig or band saw, cutting 1.5" of wood with a router will require a rather beefy router motor.
Make a first pass with the bearing riding on your template. Once this pass is complete, lower the router to cut deeper and allow the bearing to ride on the freshly cut wood. It should be exactly the same as your template after having made that first pass. Depending on what bit you have and how much wood you're actually taking off, you may even want to make 3 passes to work your way down.