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Alignment to offset holes?

Stephen McMillan
Hi all. First post. Sorry if it's a rookie question.

I want to do a Plan-Circle-Circle alignment.
The first hole is the x0 y0 origin.
The second hole has some given coordinates, say x8.0, y4.0.

I don't want to have to calculate the angle and use the "Offset angle" in the "Rotate to" field.
I also don't want to use an iterative alignment.

Any ideas?

Thanks,
Steve
Parents
  • TK, what is your basis for your statement? And where is your angle? You're using an angle, but no angle is indicated. I'm very serious here, if I'm wrong I'll admit it again (I had to admit I was wrong when I was schooled on this topic many years ago and learned this method), that's why I'm asking for reasoning. What I've seen is that the rotation method is tribal knowledge, it's the method used by most programmers because they encountered it before they knew how to do an offset line, which many people still don't, and this is the method they figured out (me, many years ago), or they were trained that way by the same.

    Where did you learn that this is the correct method?

    An angle is used because it's basic in two axes. If it was basic only in Y, you'd have a diamond parallel to the DRF (like a slot parallel to the DRF). With two basics, you have a right triangle, (functionally equivalent to a slot that is parallel to line BC. The diamond would be parallel to line BC. Thus, offset rotation.

    Your method is entirely correct when the basic dimension is only controlling the offset of C in a single axis. Which would normally mean your C feature is a slot or a target point. It is sloppy to attempt to control a circular hole in a single axis, because a circle is a closed feature where every point is equidistant from the center point. A circle/cylinder should never be assigned a single axis (even though, it happens too often).
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  • TK, what is your basis for your statement? And where is your angle? You're using an angle, but no angle is indicated. I'm very serious here, if I'm wrong I'll admit it again (I had to admit I was wrong when I was schooled on this topic many years ago and learned this method), that's why I'm asking for reasoning. What I've seen is that the rotation method is tribal knowledge, it's the method used by most programmers because they encountered it before they knew how to do an offset line, which many people still don't, and this is the method they figured out (me, many years ago), or they were trained that way by the same.

    Where did you learn that this is the correct method?

    An angle is used because it's basic in two axes. If it was basic only in Y, you'd have a diamond parallel to the DRF (like a slot parallel to the DRF). With two basics, you have a right triangle, (functionally equivalent to a slot that is parallel to line BC. The diamond would be parallel to line BC. Thus, offset rotation.

    Your method is entirely correct when the basic dimension is only controlling the offset of C in a single axis. Which would normally mean your C feature is a slot or a target point. It is sloppy to attempt to control a circular hole in a single axis, because a circle is a closed feature where every point is equidistant from the center point. A circle/cylinder should never be assigned a single axis (even though, it happens too often).
Children
  • in reply to VinniUSMC
    Well said, Vinni.

    RJ, we're not saying you're wrong, only that it depends on the print. Tell you what, if I had to correlate my CMM readings with the gage you describe I'd be forcing the the axis (offset line) to do so. I haven't seen a print so I can't determine if the gage is correct to the print so we haven't been discussing a known hence the "it depends" answers. Vinni takes more time than I have to spend here hashing what I know (started CMMs 1980s) so read it again, he said it right.

    TK
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