Tool table convention on radius end mills

[BGHansen]

I'm still a strictly G-code guy, though this applies to CAD too.

If I have a 0.125" radius end mill (for example), I mic the OD of the tool for cutter diameter (say 0.500 for my example) and touch off on the bottom for tool length. In use, I use a G41.1 or G42.1 with a "D" parameter of "0.500 - (2 * 0.125) + 0.005". I'll use a Z of "0.125 - 0.005" when cutting. That keeps me 0.005" in X/Y and Z off the surface and edge of the part so the cutter doesn't gouge.

Curious if that's how the rest of you define those tools? I could see setting the cutter diameter at the bottom of the tool and doing a "D" parameter of the diameter at the bottom + 0.005" to stay a bit off the work.

Thanks, Bruce

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[shred]

I'm still a strictly G-code guy, though this applies to CAD too.

If I have a 0.125" radius end mill (for example), I mic the OD of the tool for cutter diameter (say 0.500 for my example) and touch off on the bottom for tool length. In use, I use a G41.1 or G42.1 with a "D" parameter of "0.500 - (2 * 0.125) + 0.005". I'll use a Z of "0.125 - 0.005" when cutting. That keeps me 0.005" in X/Y and Z off the surface and edge of the part so the cutter doesn't gouge.

Curious if that's how the rest of you define those tools? I could see setting the cutter diameter at the bottom of the tool and doing a "D" parameter of the diameter at the bottom + 0.005" to stay a bit off the work.

Thanks, Bruce

You can define ball- and bull-end tools in Pathpilot, but I don't know what it does with them after that in conversational or cutter comp.

I declare them in CAD with the actual tool diameter and radius. Generally I only use them for roughing or when I want to take advantage of the radius, so I think it works best by telling the CAD system what they actually are and going from there.

Hm... on further reading, I may have misunderstood and you are probably asking about concave-radius cutters. Those are quite variable from where they are supposed to be, and one to another in my experience. Usually I'll start them pretty far off using the listed bottom diameter and tweak them in. I try not to use either the very top or the bottom of the radius if possible.