Buck & Hickman, Whitechapel "W" Marking Gauge restoration/modification...

[BentonTool]

Greetings Brothers,
I have a Buck & Hickman, Whitechapel, "W" Marking Gauge with a worn stock. The stock and stem are made of beech, but the thumbscrew appears to be made from Lignum Vitae or a rosewood (?).
I prefer slitting gauges, so I modified this one and added "golden" cocobolo to the wearing surface of the stock. I made the slitting blade from HSS bandsaw stock and the wedge from discarded ebony piano keys.
The stock had a lot of those annoying bruises from thumbscrew indentations, so I placed a leather pad in the thumbscrew hole for a cushion.

Does anyone know why there is a "notch" on the end of most of these older thumbscrews?
Does anyone know how to make these thumbscrews? It might be the subject of a good post.

 

[rob1693]

I have a very simarlar one no markings on it at all

 

[Richard_C]

I wonder if the notch, which is square sided not round, is to let you put a bar of some kind (screwdriver shaft?) across to undo it if it sticks? I can imagine it sticking if left for a few days on the same setting.

 

[BentonTool]

I wonder if the notch, which is square sided not round, is to let you put a bar of some kind (screwdriver shaft?) across to undo it if it sticks? I can imagine it sticking if left for a few days on the same setting.

I have always thought that it was placed there during the process of cutting the threads. Perhaps to drive it through the thread-cutting box? I really do not know, but have always been very curious. Most of the older ones I have in my collection have this notch.
I bought two pallet-loads of cocobolo from a business that was closing many years ago. I want to try building a few slitting gauges from my large collection of cocobolo, but have never tired cutting threads in wood.