28-12-2019, 10:47 PM
(This post was last modified: 28-12-2019, 11:37 PM by Colin Morgan.)
Looks like the variation in head size and bolt size are a bit non-linear to compensate on the smaller sizes - so perhaps, from the numbers, the formula is similar to the above, but with one change:
Head size = 1.5 x bolt dia + a constant 1/6" (~0.16", 4.2mm), which shows up most on the smaller sizes.
For example, the bolt size of 1/8" (0.125", 3.175mm) has head size 0.34" (8.64mm) AF (which can be made up of 0.1875" + 0.15") and for the bolt size of 1" (25.4mm) is the head size is 1.67" AF so is 1.50" plus 0.17".
Before calculators and spreadsheets this must have been lengthy to work out - especially in fractions of an inch - with inevitable rounding errors.
Head size = 1.5 x bolt dia + a constant 1/6" (~0.16", 4.2mm), which shows up most on the smaller sizes.
For example, the bolt size of 1/8" (0.125", 3.175mm) has head size 0.34" (8.64mm) AF (which can be made up of 0.1875" + 0.15") and for the bolt size of 1" (25.4mm) is the head size is 1.67" AF so is 1.50" plus 0.17".
Before calculators and spreadsheets this must have been lengthy to work out - especially in fractions of an inch - with inevitable rounding errors.