Screw Grading

[Seano]

This may be a daft question but, can anyone explain to me the grading of wood screws ie, 10x8 is the dia of the screw related to SWG or.... i know one measurement is the length of shaft from below head to point but no one can explain how the dia is worked out..... is it the dia of the thread or the dia of the shank

 

[rtbcomp]

This might help

http://www.classicmarine.co.uk/specpages/screwgauge.htm

The diameter appears to be the size of the clearance hole, which will be the diameter of the shank below the head, plus a bit for luck.

Standard Wire Gauge (SWG) works the other way round, smaller number is larger diameter.

 

[tigler]

This may also help :-

http://www.wlfuller.com/html/wood_screw_chart.html

 

[Seano]

Cheers chaps, have a large one on me....