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Tool grinder recommendation for fly cutters

MrStretch

Hot Rolled
Joined
Mar 20, 2017
Hello all, I am looking at eventually acquiring a small or benchtop tool grinder that can grind symmetric forms in small (1/8"?) Square hss tool bits. I would like to be able to make reasonably accurate clock wheel and pinion cutting bits, so i need to be able to grind internal radii, side clearance and circular clearance at the tip.
Would a Deckel-type tool work?

Thanks.
 
An SO-style single-point tool grinder would not be your best friend for this sort of thing, no.
Machines like the Cinninatti Monoset or the Pratt&Whitney R8/R8 are the best platforms for this kind of thing, but even they would have need some assistance in the form of dressing grinding wheels with custom forms to do involute or cycloidal cutting surfaces.

If I were equipping myself for this task, I'd focus on dressers to shape the desired radii/forms on conventional grinding wheels, and make or obtain a fixture that can provide the necessary circular/axial clearance, and probably index the tool for an appropriate number of flutes. Something like a Royal Oak form relieving fixture or a Weldon Model S relieving fixture. I'd use a conventional surface grinder or a tool-and-cutter grinder like a Cincinnati #2 to spin the wheels.

Added in edit: If your focus is on fly cutters specifically, then you can shop-make a pretty simple fixture that will grind your cutters with the necessary relief. For the sake of discussion, suppose you will mount your cutters in their arbor with zero rake. The top surface of the cutter blank is on the centerline of the cutting arbor. Make a grinding arbor that clamps the top surface of the cutter blank below the centerline. (How much below determines how much clearance you will grind.) Dress the desired profile on the grinding wheel. Rotating the grinding arbor, plunge (gently! gradually!) the cutter blank end into the grinding wheel. When you remove the cutter from the grinding arbor and replace it on the cutting arbor, it will have clearance. That very brief sketch ignores the variation of form you get from offsetting the top surface from the centerline, but the necessary compensation was understood by form-tool makers 100 years ago.
 








 
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