Item MA4 -  Micrometer Ring.  With Three Brown & Sharpe Micrometer Thimbles

Engaging, once again, my penchant for finding uncommon and unusual tools, I’ve obtained this heavy steel “micrometer ring” that is hand stamped, “for measuring 3 flute staybolt taps.”  The three micrometer thimbles are marked by Brown & Sharp, and read to thousandths.  They are fixed in the top of the ring, which is also marked “BS”.  This was likely a special order item from Brown & Sharp.  Staybolt taps are oversize taps that may range from 16” to 42” in length.  They include a lower tapered reaming section, followed by a tapered threading section, followed by a straight threading section, and topped with shank.  The varying diameters along the length of the tap, require careful machining—hence the need for a caliper like this one.  It is an interesting tool, and is in Fine condition. Incidentally, this tool will accurately measure the radius of any cylindrical object with a radius of less than 1 inch.   I’ve never seen another one, and will probably not find one again.  For the machinist who has nearly everything!  Fine

Price -  $50.00

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