Assembly Using Point and Composite Curves

I have a composite curve made from a helix. It appears that another component with a datum point on it cannot be made to mate with the composite curve. However if the composite curve is straight it can be. I am trying to assemble in such way that the component with the point in it can travel along the helix. Thoughts - suggestions?

SW 2006


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I think you can mate to the composite curve, but then the point will stick to the same segment of the curve, right ? The trick is to turn your composite curve into a real curve made of a single spline. You can do this using Tools/Spline Tools/Fit Spline...

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Philippe Guglielmetti

If I draw for example a 3D spline an then turn that sketch into a composite curve (as in my helix). If I then take that part into an assembly and select on the mate tool and select the composite curve which is 3D. SW returns cannot use for mate. However if I draw a 2d line an make that into a composite curve it will allow me to select for a mate. SO until I can actually select the 3D curve in assembly mode I am stuck.

What I am trying to do is a cam follower type of thing were the helix curve is the path I want to follow (the cam) and want a point on another part(the follower) to be mated to that cam path.

I may be out of luck.

Philippe Guglielmetti wrote:

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Sweep a dummy surface along the curve and use the surface's edge?

Reply to
Dale Dunn

Have you tried the combination of a concentric and a rack and pinion mate? The concentric would cause the part to rotate, and the rack and pinion would make it translate.

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If it is a composite curve, it is made form a helix AND something else, right? Otherwise, you would have just tried to mate to the helix without doing the composite curve.

If my assumption is right, try the following: When making the mate, do not pick the composite curve on the screen. Pick it from the feature tree.

I haven't tried this with mates (that I can recall) but I have done it (many times, for many years) with sketch relations.

If you have a point in a sketch and make it coincident to a composite curve by clicking the curve on the screen, you will only be coincident to the 'sub-segment' of the composite curve that you picked.

If you have a point in a sketch and make it coincident to a composite curve by clicking the curve in the feature manager, you will be coincident to EVERY segment of the composite curve - the entire curve.

If such a mate is posible, i would suspect it follows the same rule as the sketch relation

Please let me know if I my hunch is right regarding mates, or if I have my head firmly planted in my ass on this one. Thanks Ed

Reply to
Edward T Eaton

(OK, couldn't get to sleep)

Yup, head firmly up ass #1. I cannot mate a point to a composite curve picked from the tree, nor can I mate a point to a 3D sketch with edges converted from the composite curve if picked from the tree. But I CAN get the mate you are looking for by making a point in one part (origin in my simple sample) to a 3D sketch if I do a fitspline in the 3D sketch over the edges converted into that 3D sketch from the composite curve. I just have to pick the spline from the screen - not the curve from the tree.

Head firmly up ass #2 - I meant to say 'pierce', not coincident in my previous post with sketch relations to curves picked from the tree. It's late. Ed

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Edward T Eaton

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