Baseboards on the ceiling and upside-down baseboards on walls…as strange as it sounds, these are the elements of a three-piece assembly of cove molding I created to match original 80-year-old cove molding in a newer addition to my 1930s Georgian Revival home in Winona, Minnesota.
The original molding has just a 28-degree spring angle, giving it nearly twice as much rise as run, so it was impossible to find a match. I considered a full custom molding run, but given that it was just for one room, I decided that the setup charge for custom knife-grinding was cost-prohibitive—so I set about milling it myself.
This is a unique process—wood milled at an oblique angle behaves differently than wood fed parallel to the blade. Not only is kickback a potential problem, but the unique approach angle makes predicting the direction of kickbacks challenging. In addition, the operation must be performed without a blade guard—but because the blade is barely above the table surface, the wood itself acts as a guard in a limited sense. The best way to ensure safety is by making multiple slow, shallow passes. Careful experimentation with the technique is the only way to become proficient with this method, but even those familiar with the technique are wise to go slowly and be very careful.
The upper and lower parts of the three-part molding assembly are two pieces of off-the-shelf baseboard stock with a profile that matches the original moldings in the adjacent room. The third (middle) part is an elliptical cove that I milled on a table saw by passing 1×4 molding stock over the saw blade at an oblique angle. I used a 6′ level clamped at a 30-degree angle as my fence and cut the cove in three light passes. While milling a standard cove involves centering the stock over the blade, for this elliptical version, the curve is milled with a tighter radius shifted to one side of the molding and feathered into an angled saw cut at the lower edge of the profile.
The cove in this molding is created from the outside in—you start by milling the angled edges of the molding first; milling the cove into the face of the molding is one of the final steps.
To make the four cuts needed for the edges of the molding, I set the saw blade to 28 degrees (the spring angle of the original molding). All four edge cuts can be made with the same blade setting by simply moving the fence and by making some passes with the stock horizontal and some with it positioned vertically. The cuts must be made in a specific order, or the stock won’t have the edge needed to make the next cut.
The initial cut is made with the stock placed vertically, the fence on the left, and the blade set at 17 degrees. This is a kerf cut that will eventually become the bottom portion of the cove face, so it should only go about 1 3⁄8″ into the stock. The next four cuts are all made with the blade at 28 degrees; they will remove the corners at the edges of the cove. (The cuts meet to create a 90-degree corner at the top right and bottom left of the molding.) The first cut is made with the stock vertical and the fence to the right to shape the edge of the molding where it meets the wall. The second cut, with the stock flat and the fence to the left, shapes the edge of the molding that will meet the ceiling. The third and fourth cuts repeat the process on the other end of the stock; the third is a vertical cut with the fence to the right, while the fourth is a flat cut with the fence to the right. Once all four corners have been cut, the cove is milled at an oblique angle in three slow, shallow passes.
After the edges have been cut, the cove is milled by passing the stock over the blade three times, carving out very little material on the first pass and raising the blade slightly for each additional pass. To create the oblique angle needed for the cove, I removed the stock fence on the saw and clamped a level to the table at a 30-degree angle to serve as the fence.
After all the cuts were made, I sanded the face of the molding with a ¼” sheet sander, smoothing out the transition between the concave upper portion of the cove face and the angled cut on the lower portion. The molding was then primed to prepare it for installation.
To join the finished sections of cove, I cut a 22.5-degree scarf joint on the end of each piece to splice them together. Scarf joints are generally favored by restoration carpenters for historic accuracy—and because they are harder to see, provide more surface area for glue to bond to, and allow the two pieces to be through-nailed to each other, rather than just nailed to the backing. For this assembly, I stapled a 12″-long, 2″-wide rip of ¼” plywood to the back of the cove to reinforce the scarf joint.
Using a featherboard to help feed the wood into the saw will help make vertical cuts safer. This project requires the fence to be to the left of an angled blade for two cuts, which is normally a no-no, but using a featherboard helps to keep it safe. I set the featherboard on an MDF sled board, which held the board nicely against the fence while keeping it from squeezing the kerf together and binding on the blade.
To install the moldings, I used a marking block to determine the proper position for the two strips of baseboard that would become the edges of the molding, then nailed the baseboard pieces to the wall and ceiling with finish nails. The baseboards function as a nailing surface for the cove layer, which is attached directly in the center of the two baseboard layers to provide a consistent reveal on either side. Once the moldings were installed, I sanded along the scarfs to remove minor variations in profile and blend the pieces together. Once the finished assembly was painted, it was virtually indistinguishable from the original molding in the adjacent room.
Brian Campbell restores historic homes as the owner of Basswood Architectural Carpentry in Winona, Minnesota.Published in: Old-House Journal February/March 2012