I got a note from a customer who wanted to understand better why GW Calculator works the way it does with Cut Depth on Ballnosed endmills. Specifically, he had a cut where he wanted to enter the full diameter of the tool, but he was being limited to effective diameter, which was smaller. When depth of cut is less than the radius of a ballnose, a little thought and perhaps a visual shows that the full diameter is not engaged, but just the diameter out near the end of the ball. Yet, he had a situation where the ball was down in a slot, and this is what was worrying. He sent this diagram to illustrate:
Is Cut Depth always the depth of the successive path is increased?
He wanted to enter “1.0” as the Cut Depth and still be able to get the full diameter as the Cut Width. Instead, G-Wizard treats this as though the top of the material was the top dimension line for the “1.0” dimension–less than full width.
Why is that?
The way to approach the geometry problem posed is to understand that Cut Depth is defined as the total depth of the tool that is actively making chips. For this example, it is equal to the radius of the cutter, not the distance the cutter has moved on successive passes. But let’s put definition issues aside and consider what the Cut Depth does to the calculations. That’s what matters and it will explain why we want to enter the full length of the cutter actively making chips.
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