Alignment to offset holes?

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

Ironhoe over 14 years ago

offset line
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John Kingston over 14 years ago

Offset X 8
Offset Y 4

though those might be -8 and/or -4 depending on the print.
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Tested over 14 years ago

Unless you are perfectly aligned to the CMM offsetting X8 and Y4 will not do the trick alone.
You will need to do this process over and over again dimensioning the features after each try to see if you have achieved the offset you needed.

Example of an extreme case would be if you had your part setting at a 45° angle.
Moving X8 and Y4 doesn't give you the offset you are looking for.
Each part could theoretically be different and each need a different number of iterations to get the x8, y4 offset
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inspector212 over 14 years ago

Make sure you level to the DCC plane before you create the offset line, otherwise you will be in machine coords when you create the offset line and when leveled to the plane, your alignment will be slightly off. Is there a position callout to the offset hole? If so what is the tolerance zone shape, diameter or parallel planes? This may dictate which basic you offset.

You can offset 4 or 8 or trig the angle and all will be correct. You should clarify with the Engineer before you proceed.
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rsegriggy over 14 years ago

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

Why?
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Jimmy Hirsch over 14 years ago

Why?

exactly.......???
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johnP over 14 years ago

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

You've said what you don't want to do.

But you didn't say why!

What do you want from us?
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John Riggins over 14 years ago

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

Thanks,
Steve

I have found that doing exactly what you don't want to do yields the most forgiving results.
Parts will look better if you do the rotation based on the angle.
Easy to calculate with this: http://www.engineersedge.com/calculators/triangle_solution_menu.htm

The angle for your 8X4 example would be: 26.56505
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Lab_ratt over 14 years ago

I have found that doing exactly what you don't want to do yields the most forgiving results.
Parts will look better if you do the rotation based on the angle.
Easy to calculate with this: http://www.engineersedge.com/calculators/triangle_solution_menu.htm

The angle for your 8X4 example would be: 26.56505

there's a very important lesson for you here, weedhopper

I'd pay attention to it
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lambo over 14 years ago
Some CMM software allows you to rotate to hole’s coordinate, some don’t and PC-DMIS is one of them, but you can achieve the same result by using math in your part alignment and let PC-DMIS calculates it for you. Try this:

A3 =ALIGNMENT/START,RECALL:STARTUP,LIST=YES ALIGNMENT/ROTATE_CIRCLE,XPLUS,TO,CIR1,AND,CIR2,ABOUT,ZPLUS ALIGNMENT/ROTATE_OFFSET,[COLOR="red"]-(RAD2DEG(ATAN(4/8)))[/COLOR],ABOUT,ZPLUS ALIGNMENT/END
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