I am suffering from tenonitis. No not tendonitis, in which i would have a condition where the tissue connecting muscle to bone becomes inflamed. No, but rather tenonitis. For those of you who might be Web MD addicts, you won’t find it listed there. Tenonitis is the condition of the mind getting inflamed by continuous repetitive sawing and boring of mortise and tenons.
The problem begins when you start making mortise and tenons. The tenon is a projection on the end of a piece of wood is insertion into a rectangular hole, which is the mortise.
Typically today’s modern technology allows us to do this in the form of a machine. A few methods might be with a router, mortising machine, a table saw, or bandsaw. The table saw and mortising machine are what I prefer, but the machines had their limits. In this case, they weren’t capable to reach the depth of what I needed. So i had to resort to the tried and true method of cutting them by hand.
In most cases the tenon is ⅓ of the material. For example, if i was making a cabinet door from ¾” stock my tenon would be ¼” thick. For most projects this would be fine. But I am building a dining room table and my material is much thicker. The top and aprons are 1 ½” thick. I know during the course of this table’s life people will lean, sit, and probably stand on the table at some point and time. So I am going to alter my normal ⅓ method and beef up the tenons. I decided to divide it in half. I’ll take 1 ½” divide it by 2 giving me ¾” thick tenon. The remaining ¾” gets divided again. This makes the shoulders of the tenon ⅜” each.
The top has breadboards on the end. A breadboard is a piece that runs perpendicular to the others. The purpose of the beadboard is to help keep the longer boards from cupping and twisting. The way this is done is the breadboard has a series of mortises in it. The longer boards have tenons. Thus the breadboard keeps the long boards flat.
A couple of small points to add to the success of a flat top is the use of a stub tenon. It runs the whole length of the long boards. Think of the stub tenon as a tongue and groove joint. Also, the middle tenon is a snuggle fit to it’s mortise. But the other mortises are slightly wider. This allows the top to expand and contract during the seasons without cracking and splitting. I only glued the middle tenon. The other are fastened using a drawbored method. (I will discuss this in the next blog)
As I mentioned before, I know people will lean and sit on the edge of this table. So i had to make my tenons half of the width of the breadboard. The breadboard is 8” wide, so the tenons were 4” in length. Over all I have a total of 20 tenons that are 4” in length and ¾” wide. The making of this many tenons can and will result in tenonitis.
But i can rest assure that the top will last for many generations of family dinners whether they sit at it, lean on it, or even……dance on it.