This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Bolts. The bolt is one of the oldest and simplest contrivances for securing different parts in a desired position, and is still a most necessary item of hardware. Here, weight of metal counts for as much as, if not for more than, in most other items of hardware. This weight should be balanced in the different parts to insure strength of the whole. A heavy moving rod, for example, in some bolts, is made to engage with a thin keeper-strap attached to the base by very slight tenons headed over, so that, while it is probable that it would take 2,000 pounds pressure to break the rod, a pressure of 100 pounds might be sufficient to force the keeper-strap from its base (see Fig. 50). Inasmuch as a bolt cannot be picked like a lock, its value lies in its strength to resist force, and this should always be remembered in its selection.
As a general rule, all bolts operated by a sunken thumb-piece (Fig. 51) should be avoided, for, if they "stick" - and they generally do - very little power can be exerted by the end of a thumb. There are many lever and knob devices which permit the direct application of a considerable power. Two forms of these devices are shown in Figs. 52 and 53. This point should receive attention in selecting bolts for the standing leaf of a double door, or for cupboard doors.
Fig. 50. Common Type of Bolt with Keeper-Strap.
The rod on a boit should be tapered at the end, as the two parts rarely come exactly together so as to permit the rod to enter the keepers; if it tapers, it will, as it enters, draw the door to its proper position. For drop-front drawers in linen closets, it is necessary, in order to save space, to use flush hardware - that is, hardware which does not project beyond the drawer front, which should be just inside the closet door. Fig. 54 illustrates a flush-ring cupboard catch, which will serve the purpose; it is of the type usually seen on store showcase doors; in fact, such doors throughout are good examples of the arrangement of drop-front drawers. A large size of fixture should always be chosen. Stay-chains should be put on each end of these fronts, to prevent them dropping below a horizontal position, in order both to prevent straining the hinge and to provide a strong extension to the drawer when open, whereon to lay linen.
In place of a bolt, to secure the standing leaf of a cupboard door, a knee-catch (or elbow) is often used (Fig. 55). This is more con-veniently operated than a bolt, requiring no action other than shutting the door to catch, and a simple motion to open. The largest size of this fixture should always be used.
Chain bolts (Fig. 56), are most useful in allowing the door to be opened a few inches, and yet locking it with a partial security. They are often used to permit ventilation, or to allow the inmate to learn the character of a caller before fully opening the door.
Fig. 51. Bolt with Sunken Thumb-Piece.
Fig. 53. Lever Bolt.
Fig. 53. Knob Bolt.
The ice-box door of the north piazza (see Fig. 69) needs special attention, as a slight crack will allow the warm air to reach and meet the ice. A clamp which will force the door into its frame, must be used. Fig. 57 shows a good, strong form of such a clamp; ordinary strong hinges are suitable for the door.
Door Checks and Springs. These items are referred to under the heading Buffs. A door check and spring consists of a very strong spring applied to close the door suddenly, and, in connection with it, a cylinder in which a piston runs freely until the door is nearly closed, when either the air or some oil or other liquid which cannot be frozen in the cylinder checks the rapid piston action, so that the door is closed easily and without a slam (see Fig. 58). These checks cost in place from $4.00 for light doors, to $7.00 for those of heavy type. They are fastened on the top of the door, and are no disfigurement.
Fig. 54. Flush-Ring Cupboard Catch.
Fig. 55. Knee-Cateh.
Fig. 56. Chain Bolt, Allowing Door to be Partially Opened.
These springs are always in action, so that, if it is ever desired to leave the door open, some appliance must be used to accomplish this purpose. As they do not generally permit the doors to swing back against the wall where hooks could be used, foot-bolts are placed on the bottom rail; these have a Hat top which can be pressed by the foot into a slot in the floor.
Fig. 57. Refrigerator Clamp.
There are also on the market types of patented bolts, one of which, when pushed by the foot, is forced by a strong spring against the floor the end of the rod is protected by a heavy rubber buffer, the friction of which on the floor is sufficient to hold the door in any position (Fig. 59). Fig. 60 is another convenient type of door-holder, its method of operation being self-evident.
Fig. 58. Door Check and Spring.
Kick plates and push plates, while not often needed in house hardware - except, possibly, for double-acting doors - are plates of metal not less than 1/16- inch thick screwed onto the face of the door to protect it from wear. The kick plate, as its name implies, is the plate put on the bottom rail where persons are likely to apply the foot in kicking the door open. In public buildings, such plates are often put on for ornament; and also, where the surrounding finish is of marble, these plates protect the finish of the doors from the soap and often acid, used in cleaning the floor and base marble. It is needless to say that for such uses, the perfectly plain plate is alone appropriate. Push plates are used to protect the finish of doors where persons push them open with the hand. If they are not used, the finish on the doors soon shows where the pressure is applied, and later it will be completely worn off.