Got to do a small repair for an old lady that lives up the road, which
involves making a new ferrule to fit into the arm of a magnifying
light. Current part is a zinc casting where the internal thread has
The weird thing is that the bolt that goes into this is 0.500" x 18
TPI thread (and I did measure correctly..) - seems a bit of an odd
size to me as I can't find it on any of my threading charts.
Anyone know what it is?
Screwcutting is not a problem (workshop back in action next week thank
goodness) but I'm just curious as to the origin of this thread.
15 years ago