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Old 02-01-2018, 11:32 PM
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M&J M&J is offline
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Join Date: Dec 2004
Location: So. Cal
Posts: 890
A 3/64" is spec for ~75% as you state. The #55 is the adjusted size for the 0-80 threads with about 53% engagement. A 1.25mm would be better mid ground spec between them. Broke many taps in the Tapmatic with the 3/64" holes in those early days. Seemed intolerant of the slightest wear with Ti. Used a variety of taps to experiment too. (Read that as noob-unskilled.)

That frustration led me to the Brubaker and Greenfield stalls at Westec to get advice tapping these small holes. For non critical outside of aerospace and biomedical he mentioned a #55 was sufficient for this application, tap life would be much improved. Initially had approached them about some blue nitride coated taps which they can do. Those were the few that would cut clean and allow good longevity. How many thousand did I want to order? LOL The guys at Tapmatic and Procunier were helpful too. After those discussions tapping holes was night day. The Tapmatic CS is great! I'd called them on other occasions to dial in RPM speeds for other applications. They'd follow up to see how it went.

The rest are clearance holes for through hole and socket head.

Thinking of tap breakage along with screw breakage. Had a person ask me how I became adept at removing broken screws. That was through enough occasions extracting broken 0-80' taps and stripped screws without ruining the piece they were in. In his case these were much larger size like 1/4-20 or 1.5-1mm which to me is easy in most instances unless they have had some form of Galvanic corrosion. Saw that also with carbon fiber seat posts and aluminum bicycle frames. Sweat is nasty stuff when it seeps into tight spaces with some metals. Whoops, became side tracked there.


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