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 any dust adhering to the oily surfaces. If dust cakes on the guide rods, it is extremely difficult to open and close the vise.
Using the vise
Undue pressure should never be applied to the vise handle, for this may break the handle, the screw head, or the front jaw. If a piece of wood is properly placed in the vise, little pressure is required to hold it securely. When tightening a piece of stock in the vise, apply a downward pressure on the handle rather than an upward pressure.
A bench equipped with a single vise should have that vise located at the left-hand side of the bench. A vise in such a position is known as a head vise, and is used for most of the work involving the use of the vise. When a second vise is located on a single bench, this vise is placed at the right-hand end, and is known as a tail vise.
In placing a piece of wood in the vise, certain rules must be followed in order that the stock will be held securely without danger of damaging the vise or the wood. As you probably know, a piece of wood is made up of cells. If too much pressure is applied to these cells, they will be compressed and broken. The greater the area of a piece of wood in contact with the vise jaws, the less danger there will be of breaking down the cell structure.
Place the wood in the vise so that as much of the material as possible comes within the faces of the vise; then apply just enough pressure to hold it securely.
There are times when it will be necessary to place a wide piece of stock in the vise with the edges in contact with the jaws. Care must be used when applying the pressure so that the wood will not be bent and split. A short length of wide lumber placed in a vise with the edge of the wood in contact with the jaws will not only split, but it may be thrown out of the vise and possibly hit someone.
If surface planing or sandpapering is to be done on wide stock or glued panels which cannot be placed between the jaws of the vise, such stock may be held securely on the bench top with the aid of the vise and bench dog.
The metalworker's vise
Safety and the vise
When not in use, the vise should be kept closed with the handle in a vertical position. Vise handles in a horizontal position may project beyond the end of the bench and injure someone.
Proper lubrication of the vise is essential for safety. Vises, particularly the rapid-acting type, that are not properly lubricated will be difficult to open and close, resulting in strain on the vise or the operator.
Improper placement of wood in a vise can often lead to injury. Wood properly placed in a vise will be held securely, and there will be no danger that it will work loose or break while it is being worked. Large pieces of stock insecurely held in the vise may work loose and fall, or throw the operator off balance.
Never use an extra lever to apply extra force to a vise handle. You might break the vise. Work should be placed low enough in the vise so that the tool operation can be accomplished by the worker without unnecessary stretching.
When placing a piece of stock in the vise, make certain that the hand and fingers holding the material are clear of the vise jaws before closing them. If it should be necessary to stoop down in front of a vise to pick up anything from the floor, be careful not to strike the extending portion of the vise.