Theoretical Circle Tangent to 3 Lines

[[An...]]

I'm trying to create a theoretical circle inside a triangular-shaped machined pocket in order to give an X/Y position for the pocket. The pocket is dimensioned with a profile tolerance, but that doesn't help the machine operator make adjustments, hence the want for X/Y position. I'm taking several points on the wall of the pocket for the profile (then calculating manually) as we don't have Curve. I then recalled these points into three 3D lines, then recalled the lines into a circle with Max Inscribed Element selected under evaluation. This doesn't work though and gives me this result:

I've tried creating 3 lines (not recalling points), then creating the circle from those and get similar results. I've also tried just selecting the points that I used to make the 3D lines. What am I doing wrong?

For reference, the pocket is only .035" deep with a nominal circle size of .408".

Thanks,

Andrew

[[Ma...]]

What would recalling your lines into a point do?

[[Ch...]]

I think there are easier ways to get the location of this triangle.

However, I have an idea boiling it down to points, its pretty length, if you don't have any luck, let me know I'll try to explain.

[[Ma...]]

Recall measured points into circle and check inscribed circle

[[Ma...]]

Another method ( based on your CAD model - shorter line is not over center ) :

• Make symmetry from line 1 and 2
• Make symmetry from line 1 and 3
• Intersection them to get center point

[[Da...]]

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That will only work if there are measured points at the tangent points. Otherwise it will fail. But your second idea about the symmetry lines was good.

[[Ja...]]

How are you checking the profile? The graphics of the profile do not help?

[[Da...]]

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Now construct a perpendicular from center point to 1 original line and double the value. 😉

[[Ma...]]

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I think author didn't ask for diameter/radius - only origin.

[[An...]]

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I tried this and it does not work. The circle is not fit to the pocket.

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This works, but is a bit messy/complicated. I guess it will have to do though.

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We aren't actually using the Profile characteristic because you can only use it with a curve (which we don't have) or circle/arc. We use a Result Element and calculate the profile based on the min and max points. This means no graphic display sadly.

[[Ma...]]

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Well one last thought.
Since you don't have a curve opt i wonder how it would work with similar steps.

• make geometry alignment
• use all three lines
• allow translation and rotation.
• make theoretical point with nominal in center of a pocket
• set point's alignment as previously geometry alignment.
• recall element into base alignment

This will give you that origin with bestfit ( our it should be possible to report that origin with Result element )

[[Cl...]]

If you know the theoretical size of the circle you can measure the two
planes opposite one another, offset them by the circle radius and intersect.
That should give you the center.