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unequal segments after pattern along an ellipse

Phenom
Phenom

Hi,

I have a problem with pattern along a curve. I have a point on an ellipse and I do a pattern geometry with constant pitch of 20 mm arc length along this ellipse:

1.jpg

 

Then I use a divide curve command and divide it with my patterned points:

2.jpg

 

I don't understand why the segments of my ellipse have not the same exact length of 20mm?!?

3.jpg

When the path is a line or circle it works OK. But it gives me unequal length segments with conics, ellipse and even spline.

Also I checked the other methods rigid and offset. The problem still exists.

Anybody has any Idea?

Thanks.

 

4 REPLIES 4

Re: unequal segments after pattern along an ellipse

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Just wondering...

Have you looked at the chord length of each segment (distance between the endpoints, not along the curve)

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled


Re: unequal segments after pattern along an ellipse

Phenom
Phenom

chord lengths are not the same too:

2018-11-12_19-59-42.jpg

and the same story in NX12.0.2 (above picture)

Re: unequal segments after pattern along an ellipse

Siemens Esteemed Contributor Siemens Esteemed Contributor
Siemens Esteemed Contributor

Hi @robot139,

 

This appears to be the same issue reported in PR 7718451: "Pattern Geometry accuracy problem along splines", which was closed as EN (Enhancement) for the following statement:

 

"There is indeed an arc length accuracy problem for this PR scenario.  Further investigation shows that fairly significant enhancement effort is needed to address this problem. At this time, this PR will be closed as an enhancement."

 

You might want to look into alternative solutions, such as creating a Point Set.  If you're interested in finding out when the ER is implemented, please open an Incident Report with GTAC and ask that you're added to the ER.

 

Regards, Ben

Re: unequal segments after pattern along an ellipse

Phenom
Phenom

Thanks Ben.