I bought this set of thread cutters recently on eBay, thinking I got a real score as they are a matched set of four and relatively old.
A couple are marked, "Henry Boker", with "Germany" underneath a symbol of an arrow, two crossed lines and a couple of stars. I did some research before I bought them and the only inference that I could find about this manufacturer was on the Davistown Museum web site. There they stated that the Henry Boker company was a prolific exporter of tools from Germany, many landing on the shores of the Americas. Nothing special there, except to me, a matched set of four average tools is much better than four different ones. I said this before in this blog, I think this comes from being raised poor and having a kitchen cupboard of mismatched glasses, cups and the like. The one shinning star in the whole kitchen was my father's matched set of beer glasses. Go figure. Anyway, I grew up with a penchant for all things matching.
Anyway, back to these thread cutters.
I need a number of adjusting and locking screws for my new shooting board so I thought this would be the perfect answer. The listing and the tools are marked; "1 1/8", "1", "3/4" and "1/2", which I assumed was the size of the d0wels used to make the screws. When they arrived, I noticed they are also marked with a second set of numbers, those being; "13", "36", "6" and "2". They make no sense to me.
The other day I stopped off a Lee Valley (just down the street from the college, tee-hee) and picked up some maple dowels, one 1/2" and one 3/4", just to give them a go. Nope, wouldn't fit. All four have sample threads or test pieces, so I measured them to try and figure things out. Just for an example, the one marked 3/4" has a test thread of 11/16", that is a measurement of the none-threaded area above the thread.
If anyone out there can enlighten me on these sizes, I would truly appreciate it.