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Posted by Don Young on January 13, 2008, 11:11 pm
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> 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
> previously.
>
> 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?
>
> Alan
>
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)
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> (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
> previously.
>
> 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?
>
> Alan
>