Curve pattern - linked sketch start point issue

[GV_SVT]

I've consistently had this problem in Creo with curve patterns. You can see in the pictures that I have several sketches (3, 4, and 5) made to represent the horizontal curve of my bolting perimeter (shown by the rectangle). I'm doing this to control the bolt perimeter's major dimensions (length and width) but have the bolt hole pattern equally spaced along each side. I don't care about the hole center to center, I only care that they're equally spaced.

The intuitive approach is to make a sketch with a projection of one of the rectangle sides as I've done with sketch 3. I then use a curve pattern to generate the instances, but to my dismay the start point is at the opposite end to where I made the original hole and there doesn't seem to be a way to change the start point.

The inability to change the start point is very surprising considering most other features (sweep, datum point along curve) have the option to change start points. I've seen a solution previously to unlink the sketch during the curve pattern generation, enter the editor, and change the start point manually. This is not an acceptable work around because it is no longer parametric to the original bolt perimeter rectangle sketch so if I make edits to the perimeter the pattern remains static.

One solution seems using the line tool instead of projection tool to ensure the line is drawn from the left to right, seemingly triggering Creo to register the first clicked point as the start point when making the curve pattern. This is seen in Sketch 4, and inversely in Sketch 5 when I drew it from right to left. This is a mediocre compromise because it breaks down when skeleton modeling and using curves in the skeleton to generate patterns in parts. I should have the ability to change the start point upon pattern generation and not rely on me sketching it the proper way in the external feature.

Am I missing something here, or is it just the way Creo works at this time? Hopefully there is a way to change the start point without unlinking the sketch reference or relying on sketches being made in the correct click sequence.

[tbraxton · Accepted solution]

For the workflow you have proposed, do not use a linked sketch in the pattern feature. Instead of using a sketch, define the sketch in the curve pattern feature definition. If you define the sketch in the curve pattern feature definition, then you can change the start point.

This is how to change the start point while in the curve pattern feature creation UI.

• To change the start point and direction of the curve, click the References tab and click Edit to enter Sketcher mode.
• Select a curve end from the sketch as the start point for open sketches or select any vertex from the sketch for a closed sketch and click Sketch > Setup > Feature Tools > Start Point. The selected curve end or vertex is set as the start point.

[GV_SVT]

Thanks, tbraxton, for the great response! I am a bit ashamed, I forgot I can reference the external sketch through the internal sketch dialogue. It works great now.

[tbraxton]

This video shows how it works within the curve pattern UI.