A drop-leaf table typically contains a joint that is aesthetically appealing both when the leaf is up or dropped down. The table top contains a 90° ovolo with a fillet along the top edge. The drop-leaf contains a 90° cavetto (cove) with a fillet along the top edge. This joint, known as a rule joint or table joint, has the appearance of a 90° ovolo with flanking fillets when the leaf is down. When the leaf is up, the rule-joined leaves and table top are visible only as a thin line. The hinges, which are mortised into the undersurface, are concealed by the joint throughout its range.
|A rule joint, from A Manual of Carpentry and Joinery, by J. W. Riley, 1905.|
|The left board represents the drop -leaf and the right piece represents the edge of the table.|
A rule joint can be fashioned in several ways using:
- A combination of a rabbet plane and hollow and rounds
- A dedicated set of rule joint planes
- A shaper/router (pedal or electric)
Bill Anderson demonstrates clearly the traditional methods of using dedicated rule joint planes or hollow and rounds in an episode of The Woodwright's Shop called Table Joints Rule as well as the finicky process of layout and placement of the rule joint hinge.
Never trying to give up on the variety of uses of the Stanley 55 plane, I gave the rule joint a try with the "55". If you do not own or have handled this plane, you may have trouble following these instructions.
For the first attempt, I made a custom cutter from a leftover cutter to make the cove portion. To fashion the cutter, a bit of geometry is needed. See this post for details. After some fiddling, I realized that my custom cutter was so close to my existing No. 62 profile that I shouldn't have wasted my time on the custom cutter. So, just grab your Stanley 55's cutter number 62 to create the ovolo and cutter 38 to create the cove.
|Stanley 55 cutters, #38 on the left and # 62 on the right|
Make the ovolo first by placing the board with the top surface facing you in your vise and setting the #62 cutter for a fine cut. Use both fences, both main runners and the auxiliary center. The right side of the blade (where the notch on the cutter is located) should be located about 1 mm inside of the edge of a 3/4" board so that the right depth stop can be used to create a consistent shape. Plane down until the that little 1mm fillet to the right of the blade is barely visible. Once this little fillet is spotted somewhere, stop and set your depth gauge flush with this fillet (for me it usually turns out to be on the far end). Then take a few more passes to even out the ovolo.
|Front end of the Stanley 55. Employ both fences and all 3 runners. Note the barely perceptible tiny fillet. The small fillet allows the use of the right depth stop. Alternatively the fillet could be avoided by using the left depth stop.|
Your are then left with, from left to right (as viewed from the planer's view), an uncut segment, a small gap, the ovolo and a 1 mm barely perceptible fillet. Knock down the uncut left segment with a rabbet or shoulder plane and the right mini fillet with a low angle block plane.
|You are then left with, from left to right, an uncut segment, a small gap, the ovolo and a 1 mm barely perceptible fillet.|
|Removing uncut segment with a moving filletser plane.|
|The final edge of the "table top". Ignore the sliding dovetail notch...this was a scrap piece.|
For the cavetto, place your #38 cutter in the Stanley 55. You will notice that the main skate/runner sits in the center of this cutter. If your Stanley 55 has its left depth gauge, this is one of those rare times when you will need it. You will need to install the left gauge before the next step. Place the additional auxiliary center skate and left skate so that all three skates are abutting each other and adjust the depths of the skate for a fine cut. The depth of the fillet of the ovolo from the table top needs to be transferred to the leaf. Use a depth gauge to measure the distance from the table top surface to the top edge of the ovolo. Place your drop down leaf in the vise so that the top surface faces you. Transfer the depth of the fillet to the drop leaf. Then line up the left edge of the cutter with this mark. Plane down until you are close. By placing your ovolo piece into the cavetto piece, you will know how deep to make the cavetto. Adjust the left depth stop as needed. You may need to take a sliver or two off of the right edge with a block plane for a tight fit.
That should do it for the rule joint. Resurrect your 99% nickel-plated Stanley 55 out of its pristine minty box and try a rule joint.
|The Stanley 55 loaded with the #38 cutter. About 2/5 of the cutter on the side of the right fence (as seen on the left of this photo) will not be used for this operation.|
If the fit is good on these test pieces, save them as a template so that you can cut out a few of these steps if using another 3/4" board. You can set your fence positions and depth stops with these templates.
|This ovolo, with fillet along the top edge, would be the edge of the fixed table top. Being satisfied with the fit, I saved this as a template for future rule joints.|
|The cavetto (cove) for the drop-leaf can be made with the #38 cutter or even the #113 cutter.|