EcrosTechWiki | Woodworking / Recipe for Master Bathroom Window Molding

Ingredients

¾" thick hardwood stock, for example poplar, into which the molding shape is to be cut.

Instructions

Step 1 (Optional) — On the table saw, cut a 3/16" high by 3/16" deep rabbet (notch) at the bottom outer edge (as shown in the diagram at left, relative to the final shape, which is dotted). This is just to reduce the amount of wood that the router has to remove at the next step. If I'm at the table saw, preparing the workpiece, I might as well do this, but it isn't really necessary.

Step 2 — Fit a ¼" cove bit with follower bearing to the router. Set the top of the cutter blades 5/16" above the table surface (so that there will be a 1/16" vertical edge below the cove). With the workpiece flat on the table, using the follower, cut the bottom outer edge (as shown in the diagram at left).

Step 3 — Fit a 1/8" roundover bit with follower bearing to the router. Set the height just under ¼" higher that normal for a simple roundover. Put another way, the pointy part of the carbide cutters needs to be just under ¼" above the table surface. Hold the workpiece up on edge with the uncut side (top) towards you. Run the cut side (bottom) along the follower bearing so that the vertical edge below the cove (see above) gets the roundover. Remember that the vertical edge is only 1/16" deep. If the 1/8" roundover bit were set a full ¼" above the table, it would dig into the cove surface. Setting it slightly lower avoids this and the transition in the curves can be easily removed by sanding (Step 7, below).

Step 4 — Fit a ¼" roundover bit with follower bearing to the router. Set the height of the bit normally, i.e. to create a roundover that merges smoothly into both the vertical face that the follower runs against and the horizontal face against the router table. Hold the workpiece flat but upside-down and cut the top outer edge (as shown in the diagram at left). Optionally, turn the workpiece up on edge and repeat the cut from the face. This may result in a smoother transition and less sanding.

Step 5 — Raise the ¼" roundover bit so that the corner of the cutter (the pointy part), that would normally be at table level, is now 1/16" † above the table surface. For this cut, ignore the follower bearing and instead use the fence. Hold the workpiece at a 45° angle to the table surface and cut underneath the roundover made in Step 4 (as shown in the diagram at left).

† The height of 1/16" assumes that Step 3 was carried out as described. It is also possible to skip Step 3 and sand the sharp edge under the cove into a roundover at Step 7. In this case, the bit should be raised higher in this step. This is because the workpiece will be resting on the sharp corner left by Step 3 and not the rounded edge produced at Step 3.

Step 6 — Step 5 will leave a small but obvious ridge. This can be carefully sanded off or removed as follows. Fit the 5/8" chamfer bit to the router completely above the table so that the bottom of the bit is 3/32" above the table surface. Ignore the follower bearing. Position the fence with the bit almost completely inside the "mouse hole". Shave off the ridge.

Step 7 — Sand the workpiece to smooth out the transitions between the curves.