UNRAVELLING THE MYSTERY OF SCREWS!
How often have you started to do a small job in the house only to find you don’t have a suitable screw! They are either too fat, too long, not fat enough or not long enough. If by some miracle the screw fits, you don’t have a rawl plug!
A trip to the DIY shop beckons, but by the time you have found the screws, sorted out which size and which head shape you want, queued at the checkout and got home, there is no time left to do the job.
Sounds familiar – well here is a little bit of basic information which may help in future.
I must thank Mr. George Gouraud for the following information regarding a screw which I have omitted.
“It is a Canadian invention called the Robertson Head. This screw has a square, flat bottomed “slot” and is available in all the sizes found in other head styles, as well as having 4″ slot sizes. The advantages of this type of head are:-
1: It will not “cam out” as you tighten or loosen it, as happens with the Phillips head.
2: The screw can be placed onthe driver bit and will stay there even if you are driving it into either an overhead or downward facing work piece.”
Thank you Mr. Gouraud.
My thanks to Jason Lee Olson for correcting the original formula shown
Jason has also suggested you could convert thescrew number to to decimal
Screw No. 8 – .008 x 13 + .060 = .164 (No. 8 diameter in inches)
Screw No. 6 – .006 x 13 + .060 = .138 (No. 6 diameter in inches)
Should you require the diameter in mm then multiply the answer by 25.4.
Screw No. 8 – .008 x 13 + .060 = .164 (No. 8 diameter in inches) x 25.4 = 4.166 diameter in mm
Screw No. 6 – .006 x 13 + .060 = .138 (No. 6 diameter in inches) x 25.4 = 3.505 diameter in mm