I can't find a triple fluted router bit big enough to run grooves in 3-1/2" wide window trim. Ideally the carbide cutters would be a total of 3" wide to leave 1/4" on each side of the 3-1/2" trim. Is there such a bit? or do I need to look into the world of shaper cutters?
Fluting is a traditional decoration which consists of a series of semi-circular grooves cut into a column or pilaster (a flat column applied to a surface). Fluting has a wide variety of applications and is used in both furniture and architectural woodwork and even kitchen cabinets.
Traditional fluting is spaced so that the spaces between each flute is less than the flutes that flank it. The flutes can run the entire length of the piece to which they are applied or, for added visual interest, they can be stopped at each end. For even greater detail, the ends of the flutes at the base can be carved with a reverse profile.
To create a production run of fluted pilasters the most efficient option is to use a shaper and power feeder. The workpiece is positioned on edge and a wide cutter is used which cuts all of the flutes at once. However, using the shaper for fluting has it's disadvantages, too; the size and spacing of the flutes is limited to the shaper cutter and it is not practical to stop the flutes when using a shaper.
In contrast to the shaper, a table-mounted router and a core box bit, such as Amana Tool no.45946, allows much greater flexibility in the size and spacing of the flutes. Additionally, the router and a core box bit makes it much easier to stop the flutes instead of running them through.