International Association of Penturners - View Single Post - Parker Duofold section to body threads?
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Old 11-09-2017, 08:41 AM   #5 (permalink)
duncsuss's Avatar
Join Date: Jun 2012
Location: Wilmington, MA
Posts: 1,292
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Glad you posted, I'd forgotten. Here's what I find when I measure mine:

The diameter of the un-threaded portion behind the threads (which looks the same as the major diameter of the threads) is 8.72mm (0.343", 11/32")

The diameter of portion which slips through the barrel threads (which looks the same as the minor diameter of the threads) is 8.06mm (0.317", 41/128").

Attempting to line up the peaks of my M9 x 0.75 tap with the valleys in the section, it looks like 0.75 is a very close match. My eyes (even with a x10 visor on) aren't good enough for me to say if it's an exact match.

If this really is a metric tap. I'd be inclined to guess at M 8.75 x 0.75.

Duncan Suss
website: FruitOfTheLathe | facebook: FruitOfTheLathe

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