Trouble with capping boundary blend

[pimm]

I have a troublesome rib that I'm developing.

The contour is variable through the length but towards the 2 ends the opening is a true diameter.

I can throw an axis on the edge of the opening and revolve a diameter, but unfortunately there is tangency angling into the end opening and the resulting diameter doesn't cross the true center of the open diameter, meaning the Revolve is not tangent with the Boundary Blend.

I've tried applying a Sweep through the red intersect curve shown in the attachment using the edge of the opening but could not get a result that worked.

I tried ISDX but it didn't allow tangency at the intersect with the edge.

I've also tried different combinations of Boundary Blend with no success.

In our other CAD software we would only need to use the Fill Gap command and as long as there was good tangency the problem was over with 2 clicks.

In my opinion this should be simple yet it's got me at wits end.

Any ideas in how to close this up with a tangent round surface?

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[TomD.inPDX · Accepted solution]

You can do a boundary blend between a "true dome" segment and the edge of the rib body.

Be sure to select the intent edge of both features.

[pimm]

This sounds like a very good idea Antonius.

As long as I can establish a true position for the dome feature I'm thinking this might get me past this difficult feature.

I will give this a try.

[pimm]

Antonius: I was able to successfully apply your suggestion. I had a little more curvature than I would like just because of how the directions of the dome and open end applied with each other. I could have got something a little more perfect in shape but I tried to match the intersection with the highlighted red curve.

What I like about your suggestion is that it doesn't place a converge on any corner. Thank you for helping me get past this bugger.

[TomD.inPDX]

Glad I could help, Paul.

Have a look at the "stretch value" (1st image in the previous post). Setting this at less than 1 will make the transition "sooner".

Boundary blends have other very useful options such as guide curves and alike. I am no expert at this, but overall, this is a very powerful command for such challenges.

[pimm]

I tried the stretch value. In this application it didn't seem to get the desired effect but I'll certainly keep this in mind as I build models.

Boundary Blends are without a doubt one of the best ways to put the detail you need into a part. I've got a long ways to go. I do appreciate getting a different approach to using this tool.

[Patriot_1776]

Nice gearshift knob!

[Inoram]

Frank, that's what I was thinking.

[TomD.inPDX]

Purely an accident

[pimm]

Hi Steven,

Yes, the opening is a true diameter. Everything along the boundary blend however is not true to any shape.

[TomD.inPDX]

I think what Paul was conveying is that the surface leading up to the circular edge was not "normal" to that edge. Therefore, the revolve could not be defined Tangent as the transition varied. A case could be made for variable section sweep but it would require a linear transition that could be followed as the sweep progressed.

[pimm]

Unfortunately this wouldn't work as the tangency coming into the open edge varies; otherwise this would be the preferred method.