Fig. 2350.
In some designs this method is reversed, the gib being prolonged in a screw-thread, as shown in [Fig. 2350], and the key head is carried over as shown. Two wing nuts are provided for adjusting the key, which enables its adjustment without the employment of a wrench or hammer.
Fig. 2351.
To prevent the end of the set-screw from raising a burr on the key, which would prevent its easy motion through the keyway, a shallow groove is sometimes cut along the key, as in [Fig. 2351] at a, the end of the set-screw binding on the bottom of that groove.
In other forms of rod a gib and key are used as well as two bolts. This not only holds the strap very firmly, but it prevents to a certain extent the pening of the back of the brass, explained with reference to [Fig. 2348]. It is obvious that in the absence of a gib the key moving under friction against the brass stretches the metal more than a gib that presses against the brass, but has no motion endways.