Create a Fan-Type Carving
With the workpiece cut to rough size, but left about 12″ longer than finished dimension, I fastened it to my work table so its front edge slightly overhung the table. I then created a jig to help guide the router. It consisted of a piece of 1/2″ Baltic birch plywood about 20″ x 8″ with a 12″ x 3/4″ square piece of straight solid attached near, and parallel to, its edge. This piece of solid would reference off the front edge of the lid while routing the piece. The only thing left was to drive in two #6 x 3/4″ screws that would rest on the back of the lid’s upper surface, and hold the Baltic birch plywood jig on an angle. The screws would be adjusted to create different length grooves for the fan.
A tracing guide collar references off the edge of the jig, while a core box bit in a router creates the groove.
Adjust the Height
The screws are adjusted to protrude even higher after the first and third pass, creating different-length grooves for the fan.
In order to reduce tear-out as the bit exits the workpiece, Brown removes a bit of material from the front edge of the lid, then starts the main cut from the back-side of the lid.
A scroll-saw, with its table angled, removes material from the front edge of the lid.
Front of the Lid
After a table saw starts a cut along both sides of the front edge of the lid, a flush trim-saw and chisel finish the cut. A carving gouge will finish off the transition from straight edge to fan carving nicely.
A round file evens out the inner scallops on the front of the fan carving.
Set up the cuts
With a 3/4″ diameter core box bit chucked in my router, I set its depth of cut to the thickness of the Baltic birch plus the amount I wanted to remove from the front portion of the lid; this was about 7/8″ total depth. I then added a tracing collar to the router’s base plate that would run against the 8″ long edge of the jig.
The final adjustment was the small screws. In order to set their height, I used a piece of scrap to check the results, then adjusted the screws until I had what I wanted. I positioned the jig on the workpiece so the routed groove would be centered on my lid, then clamped the jig in place. I also clamped a stop block to my work table, at the far end of the jig, to prevent the jig from moving.
Each pass is made on the left end of the jig, moving from the back of the lid to the front, so the router bit helps keep the router in contact with the jig. Having said that, I did rout a small amount of material on the front of the lid before making each pass. This helped reduce tear-out when the bit exits the lid.
Rout the grooves
After I made the first pass, I adjusted the screws so they protruded about 3/16″ further, re-positioned the jig for the middle/ left groove, then made the cut. I repeated this for the middle/ right groove, then adjusted the screws once again before making the final two passes on the two outer grooves.
A mix of hand and power tools
With the majority of the material removed, I used chisels to smooth the curves between the routed grooves, then used a half-round file to further fair the curves.
In order to quickly remove the material on the underside of the front edge, near the grooves, I angled my scroll-saw table and traced the shape where the front edge of the lid meets the grooved top. I then made a trim cut on the table saw to remove some waste from the front of the lid, on either side of the fan. I had to finish this cut with a flush-trim saw and a chisel. A round file was then used to smooth the inner recesses of the scallops on the front edge of the lid. I then used a sharp carving gouge to smooth the transition between the scallops and the flat portion on the front edge of the lid. A half-round file is perfect for this task.
At this point the fan is complete, but needs to be sanded. I used a fine half-round file to get rid of as many machine and hand tool marks as possible, then worked my way up from 60 grit to 220 grit.