Stopped flutes are one of my favourite woodworking details. They add an air of sophistication that can turn a nice design into an eye-catching heirloom.
You commonly find stopped flutes on columns and newel posts, as well as on fireplace and cabinet pilasters.
If the work piece is less than 42" long, you can make them quickly and easily using a table-mounted router. Full height pilasters for a tall cabinet are easier to cut using a handheld plunge router with a jig.
In this example, I was making 2" wide pilasters with two 3/8" wide flutes for a pine recycling cabinet which has a tier of drawers that are 3/4" deeper than the base cabinet. The fluted portion of the pilasters stopped about 7" from the upper end and 4" from the lower end and plinth blocks were added as another detail. The drawings illustrate a stopped flute that begins and ends 2" from the each end of the work piece.
The setup and routing technique is similar to the one described in my How to Make Stopped Chamfers article.
Here’s what you do:
Mark guide lines on your work piece to indicate where you want your flutes to start and end. I determined my start and end points using the plinth blocks that would be attached.
To keep things simple, I marked reference lines offset 2" from the start & end points, towards each end of the pilaster. These lines were extended to the back of the stock so I could see them when the work piece was face down during the routing operation.
Install a 3/8" Core Box bit in your table-mounted router and adjust the height so the widest point is just level with the router table.
Move the fence close to the bit. Slide a block of wood up to the edge of the cutter on the left and mark a pencil line on the fence. Repeat this on the right side of the bit. You now have two lines 3/8" apart which indicate where the cutter is during the routing operation.
Mark pencil lines on the fence 2” to the left and 2" to the right as measured from the marks you just made on the fence – these are your start and stop lines.
Move the fence back from the bit to where you want the centre of the flute. In my case the centre of the two flutes were 9/16 from the edges.
Start with a test piece to check your marks, practice your technique and determine the correct feed rate. To avoid burning, start moving the work piece as soon as it’s flat on the router table and lift it as soon as you reach the end mark.
Turn on the router. Hold the stock firmly against the fence with the left end raised above the bit. Align the end (or mark on the back) of the work piece with the start line on the fence. Lower the left end onto the bit and start sliding it smoothly to the left. Keep downward pressure on the piece near the bit to keep the cut depth consistent. Be sure to keep an eye on the end mark so you can be ready to stop the flute.
When the right end (or mark) reaches the right pencil mark, lift it away from the bit to stop the cut. Be sure to keep the edge flat against the fence when you’re lowering and lifting the work piece.
Rotate the piece end for end and repeat the operation to make the second flute.
Sand them by hand with 100 -150 grit paper and a sanding block. If the flutes need sanding, wrap 220 grit sandpaper around a 3/8″ drill bit. Pay particular attention to any open grain areas at the ends of the flutes. If you’re going to use stain instead of paint a final sanding with 220 grit paper is recommended.
If you’re cutting three or five flutes, set up the router to rout the centre flute first. Then adjust the fence and do the outside flutes as described above.
Hand held method
As I mentioned earlier, you can make stopped flutes using a handheld plunge router with a fence attached and stops clamped to the work piece or bench.
There’s also a very good article at World of Wood that describes a technique using shop-built “ramps” at the ends that allow the bit to smoothly exit the work piece, creating a tapered end.