topic Re: fillets with triangular patches in Inventor Forum

fillets with triangular patches

Anonymous — Wed, 09 Dec 2015 21:48:07 GMT

Hi all-

I'm using inventor 2016, relatively new to it. Very experienced with both SW and Pro.

I noticed that quite often, when creating a fillet, Inventor will use a triangular patch.

This doesn't seem to be an issue for inventor, but it may cause some issues when using stp files to export for use in other packages.

Is there some way to adjust or avoid the triangular patches?

Thanks!

Re: fillets with triangular patches

JDMather — Wed, 09 Dec 2015 21:58:38 GMT

Can you post an example?

Re: fillets with triangular patches

Anonymous — Thu, 10 Dec 2015 14:29:41 GMT

Sure- here's a quick part which I added some fillets to.

When a fillet is created with just two edges on the same plane, you get a diagonal edge between the fillets where they meet at the corner.

When a fillet is created with three edges that meet in a corner, there is a small triangular surface that is formed where the fillets meet.

Attaching images and a quick part with fillets added.

Re: fillets with triangular patches

WHolzwarth — Thu, 10 Dec 2015 15:32:59 GMT

You can get other looks by switching off the continuous edges option

Walter

Re: fillets with triangular patches

Anonymous — Thu, 10 Dec 2015 16:09:32 GMT

Danke!

Interested in other solutions if they exist, there are some cases where the corners may not be acceptable visually.

Re: fillets with triangular patches

PaulMunford — Thu, 10 Dec 2015 19:43:40 GMT

You can use the curvature analysis tool to approximate the isoparms on that surface. Is it a triangular patch or a trimmed surface?

Re: fillets with triangular patches

Anonymous — Thu, 10 Dec 2015 20:09:18 GMT

Thanks, that's great info too. That's a cool tool I didn't see until now.

I'm not sure how Inventor creates the triangular surface. I'm assuming its a patch? Or possibly it goes either way depending on the order of operations.

My question actually has as much to do with how the surface is read by another package upon import, as it does about what options are available inside Inventor.

Other packages can be really picky about importing 3 sided surfaces, patch/trim aside, especially if the accuracy settings are mismatched.

I don't pretend to completely understand the math but I was told that they will often result w/ "divide by zero" error.

The example I posted is very simple compared to a typical part with lots of fillets and corners, but now I think you all know what I mean?

Regardless, the info you all have posted is very helpful and much appreciated.

Re: fillets with triangular patches

WHolzwarth — Thu, 10 Dec 2015 20:30:55 GMT

Ohh! Ohh! That's looking like task for Johnson.

Normally this triangle would be - in theory - nothing more than a quarter of a half sphere.

But when placing a half sphere in the corner, I noticed differences between the sphere shape and the fillet.

A projected sketch at the top can't be dimensioned, too.

2016 file attached.

Walter

Re: fillets with triangular patches

WHolzwarth — Thu, 10 Dec 2015 21:09:01 GMT

Hmm. No task for Johnson, but time for a new pair of looking glasses.

I've just seen that the G2 option was used in Fillet6.

That's good for complex surfaces, but with simple geometry?

Re: fillets with triangular patches

Anonymous — Fri, 11 Dec 2015 14:39:05 GMT

Thanks WH. Who's Johnson?

G2 was enabled while I was checking to see if it made any difference in terms of how many sides the surface has or not. It didn't, but did change the curvature of the surface, as you noted.

I left it that way, since this is just a quick example.

Easy to go off on a tangent here (joke intended), but this is the root of my question-

"is there a way to control how many sides a corner fillet surface has based on settings or workflow?"

The answer is yes, but unfortunately IMHO the only solution so far will not meet many look and feel requirements. If there's other ideas, I would love to hear them.

So far I have learned some really great info from my post, hope others do too, and again appreciate all comments.