The T-head is attached to the threaded screw spindle by a rivet. The handle fits the T-head loosely to allow the handle to slide freely back and forth in the head. The handle is used to revolve the screw head, which in
The T-head is attached to the threaded screw spindle by a rivet. The handle fits the T-head loosely to allow the handle to slide freely back and forth in the head. The handle is used to revolve the screw head, which in turn applies the same motion to the threaded rod to open or close the jaws of the vise.
The yoke keeps the guide rods parallel and prevents binding; at the same time it provides a bearing for the screw at the rear end. The nut, which is set in a housing in the rear jaw, engages the threaded screw. Some vises are equipped with a dog in the front j aw. The dog is a piece of rectangular steel set into a recess in the front jaw; it can be raised or lowered. It is used in conjunction with a bench dog, which will be discussed later.
Operation of the vise
There are two types of woodworker's vises, the continuous-screw type and the rapid-acting type. The continuous-screw type has a solid nut. Its jaws are opened or closed by the continuous turning of the handle. The handle is turned clockwise to close the vise, and counterclockwise to open it.
One type of rapid-acting vise has a half-nut and a screw with an intercepted thread. The screwhead on this type has a stop pin which comes in contact with a projection on the outer face of the front vise j aw. This stop allows about three-quarters of a revolution of the handle. In order to open this vise, the handle is revolved in a counterclockwise direction as far as it will go.
This brings the two stop pins in line with one another and prevents any further motion of the handle in this direction. In this position, the front jaw can now be drawn away from the back jaw with a slight pull. While the stop pins are in the same position, the jaws may be closed by pushing the front jaw toward the back jaw. The pressure is applied, after the jaws come in contact with the material placed between them, by turning the handle in a clockwise direction.
The other type of rapid-acting vise has a clutch arrangement in place of the half-nut. The clutch is disengaged by a reverse motion of the handle, which allows the vise to be opened or closed in the same manner as above. A clockwise motion engages the clutch to apply the pressure.
Oiling the vise
Oiling a vise is a simple matter, and if done regularly many dangers can be avoided. The two important points for oiling are the guide rods and the surfaces where the screw head comes in contact with the front jaw.
Guide rods that are not oiled prevent smooth, easy movement of the vise jaws, resulting in undue wear on the threaded rod and nut. Excessive wear on the guide rods or the holes in the rear jaw casting through which these rods pass may throw the jaws out of parallel. This condition will make it very difficult to hold material securely in the vise.
The guide rods and the screw spindle should be kept free of sawdust, and they should be wiped with a cloth occasionally to remove an