Using Drills

Radio Record, Volume III, Issue 27, 17 January 1930, Page 11

Using Drills

D®SPITE the rapidity with which it wears away steel tools, ebonite ‘is. a soft material and threads cut in it are very liable to strip if any force is used, especially in holes of small size, such as those required for 4 B.A: and 6 B.A. screws. When a component has been fixed to a panel or some other piece of ebonite by means of screws it is distinctly annoying to find that one or more of these will not hold firmly. One way of dealing with the matter is to rethread the holes with a larger tap. Thus, if a 6 B.A. hole contains a stripped thread a. No. 83 drill may be passed throw. it, followed by a 4 B.A, tap, in which case, — of course, a screw of appropriate size must be used. In some cases it is impossible, or, at least, undésirable, to use a screw of larger size. In such circumstances the following "botching"

method is very useful. Warm the screw a little and smear its threads with Chatterton’s compound. Now drive it in, using just sufficient force to get it reasonably tight.: In an hour or two’s time, when the compound is hard, the serew will be found tight.