Auto-Cylinder vs Circles Constructing a Cylinder: For Perpendicularity

Which is more accurate, the auto-cylinder to plane OR 3 auto-circles (constructing a best fit, least squared, cylinder) to plane.

Essentially they should have the same result, correct?

When I run it I have a 0.0009 difference between the results.

Which number should I trust?

(I am building off of an IGES file)

Looking at previous posts I made sure that I had it set to Perp to Datum

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AndersI over 6 years ago
(Cylinder Construction)

Constructing a cylinder from circles seems to be a special case in PC-DMIS, as this will always use the hits from the circles, not the center points! Can easily be seen by constructing a cylinder from a circle pattern. A cylinder from the four center points would not have a form error of 14.2701 (and would not have 12 hits)...

CYL1 =FEAT/CYLINDER,CARTESIAN,OUT,LEAST_SQR,NO THEO/<123.857,50,0>,<0,0,-1>,86.921,0 ACTL/<123.857,50,0>,<0,0,-1>,86.921,0 CONSTR/CYLINDER,BF,CIR1,CIR2,CIR3,CIR4,, ASSIGN/V1=CYL1.NUMHITS
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AndersI over 6 years ago
(Cylinder Construction)

Constructing a cylinder from circles seems to be a special case in PC-DMIS, as this will always use the hits from the circles, not the center points! Can easily be seen by constructing a cylinder from a circle pattern. A cylinder from the four center points would not have a form error of 14.2701 (and would not have 12 hits)...

CYL1 =FEAT/CYLINDER,CARTESIAN,OUT,LEAST_SQR,NO THEO/<123.857,50,0>,<0,0,-1>,86.921,0 ACTL/<123.857,50,0>,<0,0,-1>,86.921,0 CONSTR/CYLINDER,BF,CIR1,CIR2,CIR3,CIR4,, ASSIGN/V1=CYL1.NUMHITS
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