Before I jumped into making the breadboard ends I decided to do some reading and get a little more explanation on wood movement and what role breadboard ends play.
Excerpts from Popular WoodWorking magazine website:
“Boards expand and contract at a greater rate across their width than they do along the length. How much they expand and contract is more a matter of species and final resting place than anything else.
Also, wood tends to expand and contract more actively toward the bark side of the tree than toward the heart side. When you look at the growth rings on the ends of the board, the convex side of the rings is generally more active than the concave side. When one face moves more than the other, the board ends up bowed across its width – this is what we refer to as cupping.
Straight away you should know that, structurally, breadboard ends are strictly used to control cupping; they are not meant to stop shrinkage or expansion. There is no way to keep a board from changing dimensionally.
Breadboard ends are a mechanical means to overcome a board’s natural tendency for one side to expand or contract at a greater rate than the other. Whenever you try to overcome the nature of wood, you run the risk of cracking, splitting or breaking something.”
There are a number of options which can be distilled down to 2 different approaches:
After making the mortise in the breadboard and a tenon on the top, drill a hole for a pin through both the breadboard and tenon. Elongate the hole in the tenon to create a slot parallel to the edge of the tenon in both directions to give the pin room to move. The pin is glued to the top and bottom portions of the breadboard. As the boards expand and contract the tenon is held tight lengthwise while having room to expand and contract along its width. Craftsman style and Shaker style tend to use this approach.
The other option is to secure the breadboard to the tenon from the end by cutting a slot into the outer edge of the breadboad and then cutting a narrow slot through the breadbard. A scew holds the breadboard tight on the tenon and the recessed slot allows the screw room to slide inside the slot as the board widths expand and contract. The screw becomes part of the tenon and slides in the slot in the breadboad. As you can see from the example, this is the method used to such spectacular effect in Greene and Greene furniture.
Since I am a big G&G fan, I wanted to subtly use the rounded pillow feature on the plugs that cover the screws. Rather than use a series of small plugs, I chose to use a series of different sized bars.
The tenon is 2” deep and ½” thick. The breadboard end is 4” wide, making the mortise 2” deep, but still requiring a #9×2-1/2” screw to pull the breadboard into the tenon. After setting up the router table with a ½” upcut spiral bit it took the rest of the afternoon to make the mortise, 1/8” deep per pass.
The breadboard overhangs the top by ½” on both ends. with a ½” gap on the ends of the mortises to accommodate growth. As you can see, the ends were beveled and then the sharp edges were rounded to give it a less angular appearance.
I set up the router table with a variety of stops to make the ½” slots for the plugs.
Here is the end result. Set up for each set of slots took quite a bit of time to make sure I could flip the board end for end to make the mirror on the opposite end.
After a little work with the chisels to square the ends I set up the drill press with a 1/4” brad point bit and drilled some elongated holes through the breadboards allowed for wood movement. A little more chisel work cleaned up and splinters so the hole sides were reasonably smooth.
Glue was applied to 5” of the tenon center top/bottom as recommended by most how-to videos. The glue binds the center of the boards into the center of the breadboard and ensures that the wood movement is relatively even on both sides. The breadboards were held tight with some clamps while the screws were installed.
After making sure the breadboard was centered I started installing the screws, pre-drilling pilot holes as I went along. Even with pre-drilling the holes I had one screw crack the tenon. Getting the screw tight enough to pull the breadboard tightly into the shoulder of the tenon without over tightening it was a chore.
At this point I realized the 1/4” thick breadboard top and bottom were probably too thin since I could see it move when I squeezed it. I went ahead and added a set of pins in the center to help hold things together and provide an anchor point in the center of the breadboard. The plugs were glued over the screws. Everything was sanded to 320 grit and stained with Watco dark walnut stain.
Cord access holes will be added shortly along with several coats of Arm-R-Seal.
There are probably some things I could have done differently, but the end result looks good. Hopefully, my worries about the thickness of the breadboards will prove unfounded. Comments?? Suggestions? Experiences?
Building drawer boxes and fronts are all that is left before final finishing. The numerous glass panels will be ready for pick up next week so I’d better get moving…..
-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"