There is a modern type of lock spindle, known as the =“screwless” spindle=, that permits the proper adjustment of the knobs without the use of washers and with less screws. These spindles overcome the general looseness and rattle found in the common type. A “screwless” spindle, known as the _Triplex_, is illustrated in Fig. 64. This spindle is a first-class device, and is constructed, as shown, of three parallel parts, triangular in section, which, together, form a square bar. To fasten the knob on this spindle, a setscrew in the knob bears on the center bar, and owing to their wedge form, the two side bars are forced apart and into frictional engagement with the spindle of the knob. The spindle itself is screwless, and there is nothing tending to loosen the setscrew, so that when once properly tightened, the knob will remain firm and in position on the spindle under all conditions of use. In some instances, this style of spindle has been condemned by owners and architects. This has been due largely to the fact that the mechanic did not set the screw tight against the spindle, thus allowing the knob to be easily pulled off. This is often caused by not using a screwdriver that exactly fits the head of the screw. When the knobs are put in place as they should be, this device always gives entire satisfaction. [Illustration: FIG. 64] [Illustration: FIG. 65] There is another, though somewhat costly, type in the market, known as the =wrench spindle=. This spindle is illustrated in Fig. 65. As shown, the mechanism consists of a chuck, or vise-like arrangement, formed on the knob shank. When the nut _a_ is screwed on the jaws _b_, the tendency is to grip the spindle securely, the latter being solid and without screw holes. This type of spindle allows perfect adjustment. Another type of knob spindle is the =swivel spindle=. This is used with front, vestibule, and other door locks that have stop-work, whereby the outside knob may be made operative or not, as desired. In order to accomplish this, the spindle is divided longitudinally, so that one end may rotate independently of the other. The standard sizes of spindles for door locks, etc. are ₅/₁₆ and ⅜ inch square. Occasionally, spindles as large as ½ inch square are used for large knobs or handles, such as would be used with massive lock trim. For thumb knobs and locks and latches of this character, spindles ¼ inch square are employed.