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The Woodwright's Workbook: Further Exploration in Traditional Woodcraft By Roy Underhill
Drawboring/Roubo's End Vise
The way people move about, you may well want to be able to take your bench apart. When you peg through the joints, leave the pegs protruding
on the hidden side so that you can drive them out when you want to. The pegs should be properly drawbored so that they pull the joint tight. To drawbore the joints, first bore the peg hole through the cheeks of the mortice without the tenon in place. Then put the tenon tight into the joint and, using either the lead screw of the auger used to bore the hole or a scratch awl, mark the location of the peg hole on it. Now pull the joint apart and bore the hole through the tenon, being sure to offset it about V» inch toward the shoulder of the tenon.
When you reassemble the joint, you can either drive the tapered peg straight in or -use a polished steel "draught-nayle" to make the initial compression.When you drive the peg, be sure that the underside of the morticed piece is well supported. I have seen beautiful work ruined because the offset of the hole caused the peg to miss the hole on the far side and split off the cheek.
Roubo's End Vise
I made my bench with an end vise that uses a framed out-rigger to keep it tight in the track. It is similar to the one described by Roubo, but uses a manufactured bench screw and nut.
The end vise detailed by Roubo in 1771 measures about 14 inches long and 3 l/z inches wide and Is as thick as the bench. The six sides of the box enclosing the screw are joined with tongues and grooves, rabbets, and mortice and tenon joints reinforced with glued pegs or screws. The cover piece (B, fig. 7) must be fastened with screws alone to allow access to the internal mechanism.
The back piece (D) and the end piece (F) are designed to keep the sliding box tight against the bench. Piece F (shown end-grain-on in figure 6) has an 8-inch tail which hooks over a retaining bar (G, figs. 6 and 7) on the underside of the bench top. The back piece (D, fig. 7) is langed to fit into a slot in the edge of the bench. This piece is also seen in figure 12. Figure 10 shows the side of the bench ready to receive the box, along with the retaining bar (G),
The head of the box (E) also has a special function. As shown in figure 8, it links the screw to the box so that it will open when the screw is backed off. Two keys of iron, copper, or very hard wood ride in a groove turned in the shank of the screw.
In figure 8 you can also see that the nut for the wooden screw is actually an iron case filled with a soft metal casting. This nut has a 6-ineh tail which is bolted into a mortice in the side of the bench. In the side view, figure 7, the nut is shown with its two bolts. Figure 9 shows a top view of the nut and its tail. (The following chapter will show you how to make wooden nuts and screws for vises and other devices.)
The opening through the nut for the easting must be about % inch larger than the diameter of the screw. Flare the opening on both ends and drill holes in the four sides of the nut so that the casting will be held solidly. Take a length of screw similar to that which you will use and coat it with fine clay mixed with glue. This coating gives the screw clearance and keeps the heat of the casting from scorching it.
When the coating is dry, position the screw in the nut and mold clay around it to prevent the molten metal from leaking out. Now, pour in the casting material, which is composed of two parts lead with one part antimony. When the metal is cold, remove the screw and die nut is done. The iron catches (figs. 2 and 3) which hold the work are about 3A inch square and about an inch longer than the thickness of the bench. A spring on their side holds them at the proper height. One hook may be set in any of the holes which are cut every 4 inches in a line i lh inches back from die edge of the bench, lined up with the middle of the screw. These holes are cut at an opposing angle to those in the vise box, as you see in figure 6, so the hooks stay tight and the board doesn't come loose.
Another pegging method is commonly used when the long rails pass through the horizontal bar between the legs of one end. The usual practice is to allow these tenons to pass through the end boards and hold them with a tapered key. This is the tusk tenon used in teutonic work. It is similar to the drawbored joint in that the tapered key pulls the joint tight. Be sure that the hole for the key extends back below the surface of the wood through which the tenon passes. Otherwise the peg will never be able to draw up the joint. (This is not done in Alabama, where the tusks-are-loosa.)
"The Woodwright's Workbook: Further Exploration in Traditional Woodcraft" By Roy Underhill
© 2012 The University of North Carolina Press