This is something that I've wondered about.
I generally have set up planes so that the frog in the same plane as the back of the mouth, so that the iron is supported there,
but to get a close mouth opening, the iron is supported only by the frog, about 5/16" back from the cutting edge in this example, and the chipbreaker/cap iron are in effect flexing the iron down.
What's the deal?
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