I designed the ebony table button to encourage people to touch my furniture and experience the phenomenon of wood movement.
Wood is a living, breathing organism. As one season turns to another, wood absorbs or gives-off moisture as the relative humidity around it changes. A table top, even one made of quarter-sawn wood, will have some movement across it despite its vertically orientated growth rings. The ebony table button was envisioned to couple this movement with the propensity we all seem to have for touching beautiful wood. The subtle glide of your fingers across the button, allows you to feel how much movement has occurred.
I first installed ebony table buttons on the Blue Collar table which resides in the permanent furniture collection of the Grove Park Inn and was featured in Bruce Johnson’s book Grove Park Inn Arts & Crafts Furniture. This table has a book-matched, quarter-sawn white oak top that is approximately 30″ wide. It is not uncommon for the button’s on this table to reflect a heavy 1/16th of an inch of movement from season to season.
To begin making the ebony table buttons mill up some white oak and ebony. The thickness should be a heavy 3/4″. The width should be relative to your available stock and how many buttons can be cut across it while minimizing waste. The length should be relative to what is necessary to yield your buttons while providing enough material for hold-down and safety concerns.
I use a slot and tenon joint to bring the ebony and oak together. Begin making this joint by cutting a slot on both edges of the oak with a 1/8″ slot cutter set to a depth of 1/2″. A piece of brass bar stock is an excellent set-up guide for determining the slot cutter height.
With the slot cut in the oak, I turn my attention to milling a tenon on the ebony stock. This two-step process involves removing a 1/2″ deep chunk of material from both faces of the ebony edges to reveal a tenon. I use the slot in the oak stock as a guide to set the height of the first cut. Then, on the second cut, I set the cutter height to produce an 1/8″ thick tenon. I usually start with an initial pass that produce a thick tenon and than incrementally raise the cutter on successive cuts to sneak up on a tenon that fits snuggly into the slot.
If your making a lot of buttons it may make sense, when milling up your stock, to make a few pieces of poplar, identical in size as the ebony, for make test cuts while setting the final cutter height.
Once the tenon is formed, cut the ebony cap from the stock.
Next I glue up the button, joining the oak and ebony together.
Remember we milled our stock a heavy 3/4″. We did this because rarely will you get the ebony and oak stock to align perfectly. Now with the aid of a drum sander bring the stock to 3/4″ thickness and smooth the transitions between the oak and ebony.
Next, start shaping the buttons. This is another excellent application for brass bar stock. Use it to set the height of the cutter to remove 3/8″ of material, and set your fence to form a button tongue length that is 1 1/8″. I find this length to work good with 3/4″ thick table aprons. If your aprons are thicker you may need longer tabs.
With the button tabs formed, it’s time to drill the holes. Using a 3/4″ inch thick button and assuming a typical table top, which is usually 3/4″ thick, I use a number 8 by 1 1/4″ screw. Begin by laying out the hole, centered on the button and 7/16″ from the closest end. Then I drill a 1/8″ pilot hole, followed by a number 8 countersink and finally an 11/64″ bit to accommodate the shank of the screw.
You’re now ready to release the buttons! I use the band saw to make the long vertical cuts and than on the table saw I free the individual buttons from the stock. This final cut can also be done on a band saw.
Finally, I establish a silky, smooth surface on the ends of the ebony by sequentially sanding them with three grits of sandpaper — 150, 220, and 400; polishing them on a red rouche charged buffing wheel; and finally buffing them out with a white buffing wheel.
Now we’re ready to install the table top.
Installing the ebony table buttons is pretty simple. The only unique step is the layout, otherwise you’re just cutting a through-tenon in the table apron, insert the ebony button flush with the apron’s outside face, and secure it to the table top with a screw.
I layout the through mortise location on the front of the apron by using my workbench to mimics the table top’s bottom. I place the button tongue up against the apron front, where I want the button to penetrate through, and trace the button’s tongue with a pencil. Remember when you go to layout the mortise, that the pencil lines regardless of their thickness, reside outside of the mortise and should be present after you’ve completed cutting the mortise. With the tongue location laid out, I’m ready to cut the through mortise. See my post Making Through Mortise and Tenon Joints for a description of how this is done.
Once the through mortise is complete, you’re ready to install the table top and get ready to feel the movement!
Some final design notes. When I’m installing the ebony table buttons on a sofa or foyer table that will rest against a wall, I use traditional table top buttons (those installed without a through mortise) to anchor the rear edge (i.e.: the edge against the sofa or wall). This forces the top’s movement toward the front, where ebony table buttons are installed to highlight the tops movement. For a table that is not going to be up against a wall, if you want to put ebony buttons on both the front and back of the table you can do so, but you’ll need to design the table’s infrastructure to anchor the top in the center which allows it to move torward both edges.