Originally posted by Apet-Sure Some of those differences in length, when only hundredths of a millimeter (ex: 6,84mm vs. 6,9mm), may simply be due to fastener manufacturing variances. When I was a design engineer, we tried to minimize the number of different fasteners in an assembly for simplicity and ease of inventory.
I am certain you are right.
But then there is a slight but important difference between those screws which screw into metal and those which screw into plastic.
Some have a slight difference in thickness, thread, lead and pitch.
That's why I take either photos of each side of the body or make a short drawing, pinch tiny holes into the places the screws are located
and stick them in there.
A simple drawing is done within few minutes.
But because I knew this was not going to be just one repair anymore, photos glued on cardboard served best.
One can actually just copy photos from the internet and print those.
So what all screws have in common:
They are all JIS!