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Ye Olde Screwplate

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vtsteam:
I bought this screwplate at the Bernardston engine meet, tossed together on a table with a bunch of other newer tools. It has a double series of die holes with gauge numbers that don't match current U.S. screw gauges (numbers of the screwplate decrease with increase in diameter) and don't match drill gauge numbers either. The pitches are 28, 32, 37-1/3, and 42-2/3. The first two are pretty familiar, the last definitely not!

vtsteam:
I think this is the maker:

Fergus OMore:
I have a homemade one. Mine has a range of BSW dies but around the edge are a number of 'notches' to take many various thicknesses of square tap ends.

Very useful - and came with the word 'stolen' I paid for it- not guilty me lud!

Norman

vtsteam:
Naturally being the curious type, I had to see if it still worked. I had a piece of 3/16" galvanized rod that fit the 7 hole and a piece of 1/8" brazing rod that seemed to fit the 12 hole.

And, yes indeed, it still works:



I didn't have the screwplate level for the steel 3/16" rod so the thread is somewhat canted. But it did check out at 32 tpi with a screw gauge. Actually, it's easy to hold the screwplate level, by eye, as I discovered on the second piece -- the broad surface makes it pretty apparent when you're off when you start the thread. If you bother to check, that is!  :wack:

The second piece mated well with the 38 tpi screw gauge for the full length of the thread. I naturally don't have anything 37-1/3 tpi to test with!

S. Heslop:
I've seen pictures of those before but never knew they cut screws. I thought they were just for checking sizes.

Was there any rationale behind having them all on the same plate though? The limitations seem obvious.

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