Relief Grinding Fixture

[msrm]

This question relates to the tap sharpening
fixture question. Will a relief grinding
fixture grind taps the proper way or are
the tap sharpening fixture and a relief
grinding fixture two totally different
animals? Are these used on a surface grinder
and/or a tool and cutter grinder?

[kgarver]

Tap releif grinding fixtures are designed to grind/regrind the ends of the taps. Say you chewed up the end of a tap or wanted to make a bottoming tap into a plug tap or even a taper tap. You would use the that fixture. They use adjusting cams (Hybco heads) or fixed cams (Weldon's tap attachemnt) to do this.

Now suppose you have a dull tap that just needs to be resharpened. You do that by radiusing a thin grinding wheel to the same radius of the tap's gullets (round undercut area of the tap where the chips go when in use) and pass the front of the flutes past it. Taps are a form ground cutter and their correct shape is ground into that "form".
FYI you resharpen all form ground cutters (gear cutters, taps, roughing shell mills [corn cob], etc.) on the front face of the cutter. Clear?

Regards, Ken