Making 14BA and smaller taps

In the past I have made a good number of small taps in sizes around 8-12BA
(although usually with other pitches) using the "watchmaker's" triangular
three sided form, which are then sharpened by rubbing on a fine arkansas
stone after hardening and tempering. These taps work quite well, even on
steel when used with care. In those days I regarded 10BA as a small tap.
I've tried making some even smaller sizes (14BA and 16BA) and have
enountered a new problem. If you don't sharpen them after tempering they
are blunt and don't cut and end up stripping the thread. But they are
so small that when trying to sharpen them on the stone, it is very easy
to accidentally round off the thread form. I've managed to make some
which work, but not nearly as well as the 12BA taps which I made
I know I could buy them (e.g. Arc Euro trade sell 14BA and 16BA)
but they don't do the even smaller sizes -- is there some trick known
to other makers of tiny taps?
Reply to
Alan Bain
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Would clamping the tap in a small cross-piece with wheels (kinda like a cannon barrel is attached to its wheels) and then rolling the whole thing across the stone work? You would have to carefully set the angles but that should hold it steady. I saw such an arrangement for sharpening jewelers' screwdrivers. It might be possible to make it three-sided somehow so that it would only have to be set once. Maybe just a triangular block without the wheels.
Don Young (USA)
Reply to
Don Young

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