Rush 132 Drill Grinder - Grinding Taps

In this video, Bill Freese grinds the lead on a four-flute tap using the Model 132 Drill Grinder.
He uses a #8 cam for the righthand drill, sets the latch in the righthand slot, sets the tap as close to the chuck as possible, and sets the lip right on top of the setting blade. The angle is determined by whether you want a taper, plug, or bottom-type drill.
These angles aren't too standard and depend on the size of the tap and the pitch of the thread, but roughly, a taper-tap on the righthand side of the scale will be set to 152 degrees for taper with cam relief set to 16; a plug tap would use a 145 degree angle and a 12 or 14 on the cam relief; and a plug lead would use an angle of 120 degrees and a cam relief setting between 0 and 4.
Keep in mind, these settings very quite a bit so specific parameters of angles and cam relief will be unique for each application.
In this case, Bill grinds a plug-lead using the side face of the wheel. After the lead is ground, the workhead can be swung over, the cam can be removed, and the face can be spun down.
It's important to get the teeth perfectly flat to the same height so they all engage at the same point in the hole and won't chip or break the tap.
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Rush Machinery
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www.RushMachinery.com
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Rush Machinery specializes in manufacturing, servicing, and marketing a line of production and support machinery for the cutting tool industry since 1983.