The whole question of period screws seems under researched which is surprising since it is a good guide to confirming dating and spotting 'restorations'. I would describe these tools as drawplates for sizing and finishing screws previously cut using an adjustable die. In the example attached different sizes appear to be grouped in pairs; same thread pitch but slightly different sizes corresponding to a first and second finishing of the thread. This can be confirmed by the example above where someone has crudely marked up the threads of corresponding pitch to avoid confusion.
Interestingly in the example attached the differential patination shows that it is a laminate with a central core of high carbon steel sandwiched between two layers of softer iron . Therefore the tool can be tempered dead hard but still be ductile enough not to break . Clever.
Small makers mark R TIMMINS possibly indistinctly , and Sons
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