Paragraph 69. The round tenon is used in joining materials where there is no great strain sidewise. It is rather easily constructed, but is not so substantial or rigid as the blind mortise and tenon, and for that reason it is not so common. It is used in wheel construction where the spoke joins the felly. It is frequently used on the end of materials where the principal pressure is downward with but little strain sidewise. For instance, in the legs of the camp stool.

Figure 54.

To Lay Out The Round Tenon Construction

Decide the length the tenon is to be and square a line entirely around the material that distance from the end (piece A). Determine the diameter of the round tenon and set the mortising gauge with the two points as far apart as the desired diameter. Set the gauge with the head at the proper distance from the first point to lay out the tenon in the center of the material. Carefully gauge the tenon on the edge of the material. With the rip saw saw down to the squared line in the same manner in which you would saw any tenon. With the two points exactly the same distance apart set the head of the marking gauge so as to lay out the tenon the proper distance from the working edge and gauge the width of the tenon on each side of the tenon already sawed. Again saw down to the shoulders. This will form a square tenon. Find the center of this square tenon by drawing the diagonals on the end. Set the compasses and on the end of the square tenon lay out a circle the size of the desired round tenon. With a pocket-knife carefully cut away the corners and make the tenon round to the size indicated on the end. It should be finished with a wood file. In this joint the mortise is to be merely a round hole (piece B). It is bored with a brace and bit of the proper size. It might be well to bore this hole before the tenon is completed so it can be tested from time to time to make sure that it is made the exact size to fill the mortise snugly. This joint may be assembled with glue or a small brad may be driven through B into the tenon, as the nature of the work may indicate.