Sweep2 knife handle problem

Knife_8"Chef.3dm.zip (305.7 KB)
I’m modeling a handle that needs to taper smoothly towards the blade but I’m getting portion that drops like a canvas between two of the profile curves. Is there something that needs to be modified to remedy this?

Try _NetworkSrf with a central driving curve.

Knife.3dm (98.4 KB)


Thanks Andy!

I :heart: NetworkSrf.

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One thing that helps avoid ugly sweeps is to keep the cross section curves as close to perpendicular to the rails as possible. In this case that means extending the sweep past where the last cross section is not perpendicular and then trimming back to get the straight edge. To maintain control of the shape down the middle I would do the handle as two surfaces so that you have a defined edge down the middle. .

In the file below the green surface is made as a loft and then extended and the 2 rail sweep is then tagent to the surface edges that are the rails.

Knifex.3dm (232.2 KB)

Hi, I’ve been at it and I’ve run into another issue. As you can see from the ss there’s a problem with a component displaying.

This is the second time I’ve remade the parts hoping whatever was a problem wouldn’t be the next time.

but no.

Knife_8"Chef.3dm.zip (2.0 MB)

I exploded it and then ran join again and it seemed to fix it?

Knife_8_Chef_2.3dm (1.8 MB)

My usual workflow is: _ShrinkTrimmedSrf _MergeAllFaces _Check

If there are strange errors I _Explode (no pun intended) and then run _Join again and repeat the first part.


Thanks Andy, I’ve been away for a month and I’m feeling rusty already. The explode rejoin worked just fine. It’s a rather weird anomaly - the display issue. I was trying to remember how to get back bits that had been trimmed and I finally remembered after reading your post. I’m working on the embossed graphics on the blade today.


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That’s a nice approach Jim. I went through it and I was wondering how you got a cleaner surface than I did sweeping the two edges.

To simplify the surface I used the rebuild cross section option - set to 8 or 9 points.

Ironically, the way to get the simplest surface is to use the “do not simplify” option. But in order for that to work all the cross section curves have to have identical knot and point structure. The easiest way to do that is to have all the cross sections single span curves. If you need more shape control than a single span can support then you can make all the cross sections as a copy of one curve and point edit to get the required shapes.

It is also a good idea to use RemoveMultiKnot after making a sweep2 surface.

Hi Jim,

I’ve progressed to another point that you may have an opinion on. That is how to best created voids of letters into a surface. I thought using some solids to do a boolean subtraction would do, however I get a fail notice. Is there some tool that’s used for such tasks?

Knife.min.3dm.zip (2.1 MB)

Letters on end of handle: The umlat symbols are not closed on the bottom. Use Cap to close them. Problem found by looking for naked edges using ShowEdges.

Lettering/logs on blade: Some of the lettering/logos do not intersect the blade surface, and a portion of the lettering/logo surfaces may be coincident or nearly coincident with the blade surface. My guess is the coincident surfaces are the problem. Found using IntersectTwoSets.

Thanks David,
It was the umlauts needed capping. I missed it. The lettering on the blade is supposed to be painted so there’s no issue with boolean.

My usual procedure for diagnosing Booleans which don’t work:

  1. Properties > Details of the objects to check that descriptions, etc are as expected.

  2. Intersect and look for intersections which are closed or run to edges,

  3. ShowEdges for naked edges and non-manifold edges


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