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Hexalobe bone screw iterative rotation tolerance

lovethepirk
We run profile of a surface on a hexalobe for several bone screws. Our quantity of checks per order just doubled. When we do an iterative alignment to cycle thru how well the screw hexalobe is oriented we commonly get an iterative error on the rotation. I do not program the part, but have discretion to make changes within reason. All the rotational tolerances are set to .006mm for the iterative tolerance, which is crazy too low in my opinion.

Even if the error pops up at .02mm on the rotation, every operator enters thru the error and the program works fine. Would it seem reasonable to set this at a max of around .0254mm or 1 thou? I don't see how a 1 thou error couldn't be allowed for the program to proceed without an error msg popping up taking a 3min program and turning it into a potential 10 min program if the operator is doing other things.

The vectors on the rotation of the hexalobe rotation are not clean either, they are far from a pure X plane direction, they have plenty of Y in them as well.
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  • Based on what you said, if this is nothing more than a rough alignment (should try to get away with a read point if that is the case instead of iterative) then you need whatever precision is required to make the real alignment find the part with a minimum of probing error (if the part is way off so its measuring a plane at a 30° contact instead of plumb, for example, that would be bad).

    Just enough to ensure your hits are close enough to true (perpendicular to the surface being hit) that you don't have error that the math can't compensate for.

    If it always runs at 0.025, and the program doesn't use that alignment for any measurement, I'd agree it is safe to change.

    A lot of ifs there, but I'm having to trust what you are saying, and I'm not known for trusting people... not even myself usually lol
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  • Based on what you said, if this is nothing more than a rough alignment (should try to get away with a read point if that is the case instead of iterative) then you need whatever precision is required to make the real alignment find the part with a minimum of probing error (if the part is way off so its measuring a plane at a 30° contact instead of plumb, for example, that would be bad).

    Just enough to ensure your hits are close enough to true (perpendicular to the surface being hit) that you don't have error that the math can't compensate for.

    If it always runs at 0.025, and the program doesn't use that alignment for any measurement, I'd agree it is safe to change.

    A lot of ifs there, but I'm having to trust what you are saying, and I'm not known for trusting people... not even myself usually lol
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