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View Full Version : Small taps: How are they made



Rotate
11-20-2002, 02:52 PM
I bought a 1M HSS tap for a repair job, and I've been wondering how they are made? Is it first rolled like a screw, hardened, and ground? I thought taps had hollow grinding, so is the thread profile machined using a profiled cutter?

Picture (http://members.rogers.com/rotate/small_tap.JPG)




[This message has been edited by Rotate (edited 11-20-2002).]

Thrud
11-20-2002, 08:41 PM
Albert
You can make taps either by grinding the profile or turning. The flutes are cut afterwards. So if you needed a custom tap, say a LH .500"-13 you get some O-1 thread it and then harden it. The last step is to grind the flutes out so the cutting edge has a slight hook (positive). Works beauty.

Only cheap crappy taps are rolled formed (carbon steel).

Forming taps (no flutes) are cam ground and usually plated with chrome or TiN to lubricate the tap somewhat - they someimes have a single thin groove along the tap to allow lubricant to get deep into holes. These work great in Aluminum and other soft metals.

[This message has been edited by Thrud (edited 11-20-2002).]

kgarver
11-21-2002, 08:35 PM
I have actually audited the manufacturing process of Greenfield Tap & Die in the south where they actually make the taps. BTW ALL Sears taps, dies and drill bits are made by GT&D. Or were about 5 yrs. ago. The large taps were rough turned and the flutes cut in them before they were hardened and then finished ground. The small ones were hardened and the teeth ground on them and then the flutes were ground out. Better to have the "meat" on the side to get good ground teeth before cutting away the flutes which added lots of support.
Regards,Ken