SCREW THREADS.

Hawera Star, Volume XLIX, 16 November 1929, Page 14

SCREW THREADS.

AVOID TROUBLE BY CAREFUL HANDLING.

’ Screw threads, while amply strong to withstand the strains for which they are designed, are very easily damaged by careless treatment, and considerable delay, and possibly a certain amount of expense, may result if the thread of an important nut or bolt is “stripped.” Fine brass threads, such as those used for petrol tank filler caps, are particularly liable to damage. The best thing to do if the threads do not engage easily is to turn the cap backwards until a slight click is heard, when the cap can usually be screwed on quite readily. When it comes to replacing a nut which has been lost, great care should be taken to ensure that the new nut is of the correct pitch. It often happens that when the threads of a. nut and bolt differ only slightly the nut can be screwed on two or three turns quite easily before it commences ,to bind, and this may lead to the belief that the stiffness is due merely to dirt or to the thread being slightly burred. To continue tightening the nut will result in the threads being crossed and the bolt itself will very likely be damaged- Another nut of the correct pitch can usually be obtained without difficulty, but the bolt or stud may be part of the car or of a kind which will be rather expensive or troublesome to replace. Another point to bear in mind is that'it is always worth while cleaning the protruding portion of a rusty or muddy bolt before attempting to remove the nut, as apart from the stiffness in unscrewing it, there is the chance that road grit will damage the thread. Paraffin iis the best cleaning medium.