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ptc-46314451-Visitor
1-Visitor
February 16, 2015
Question

Issues when offsetting a boundary blend

  • February 16, 2015
  • 1 reply
  • 4197 views

Hello -- I am wanting to create a surface for a cam follower to run on. The cam follower is making a complicated motion relative the stationary cam surface -- it is not moving in any one plane. I created 5 points on the cam axis, enough to cover the surface of the cam follower. Then I traced the curve of each point relative the future cam surface material. At that point, I created a "boundary blend" of the 5 traces. Now the problem: I have to offset the boundary blend .625" 'normal' for my 1.25" dia. roller. When I do this, I get only 1/2 the surface. If I drop down to .25" offset, I get a full surface, but it is not close to being accurate (which scares me!)

I have done this same procedure before with success. The traces make an egg-shaped path. The difference is the size of the small-end radius with my new version. My previous instance had large radii. The one I am having issues with has a very small radius on one end. One would think it is quite possible to offset this boundary blend to the outside, but it fails.

Of course, after I offset the proper amount, I "solidify" that quilt, and cut-out the path for the cam roller. I can do this with the boundary blend of the traces, and then offset that cut surface by .625", but that also fails to work. Am I overlooking something?? I am not a 'surfacing' person. Thanks for any help.


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1 reply

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ChristopherLewi12-Amethyst
12-Amethyst
February 16, 2015

IMO, these issues are always a function of the math of the original surface (your particular surface may have some kind of wrinkle in it that is ultimately confusing the systems ability to calculate the offset nicely). Even if you cut off the top a bit and attempted to offset that (to isolate the area of the surface giving you the issue) you'd still ultimately be constructing the result. One idea would be to make the patch math different using an independent geometry and modify. Maybe if you can share the data you'll get someone stepping up to send you an answer. With you stating that the offset at 0.25" being totally inaccurate, that would feel like some kind of bug that needs reporting to tech support (we should all have confidence the numbers we stick in result in those numbers being 'truths' don't we!)

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ptc-46314451-VisitorAuthor
1-Visitor
February 16, 2015

Thanks. Your question as to the surface being complicated, led me to making a boundary blend using only 2 adjacent traces, which would seem to be a simple surface, yet is representing points making traces that are rotating abut a 7" radius. Same problem: won't offset the entire surface.

Since I can "boundary blend" and solidify the 5 traces seemingly OK, I am trying to understand if it is possible to offset that cut surface somehow in my cam block? One is supposed to be able to turn a solid surface into a "quilt" and then offset that quilt, but I get a "greyed-out" offset command when attempting that.

What is the "Import Data Doctor" all about? Is that applicable here to correct the quilt?

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ptc-46314451-VisitorAuthor
1-Visitor
February 16, 2015

I am attaching a JPEG of my part. Don't see how to attach a file.Screen Capture.jpg

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