Hi Warren,

> OK, thanks for the info. I downloaded the ViaCAD demo version and the interface is ... challenged,
> I guess is the way to put it. Every time I have to use it, I predict I will be irritated. :P

It's not so bad if you use it just for filleting, that just involves picking edges.

It's filleter is significantly better at handling more complex corner cases.


> So is there a best practices for Filleting thread somewhere that I could read through
> or is it just an experience thing?

There are so many different kinds of things there isn't really just one thread that covers every kind of geometry, it somewhat depends on the particular shapes that you are dealing with.

In the future I would like to try and license one of these other geometry libraries that has more sophisticated filleting to help out with this.

Some general things to avoid - it can help to have more simple edge topology with fewer edges coming together all at one single point. Also having things meet up at a very shallow angle can make things more difficult, it's usually best for shapes to be more distinctly sharp to one another or more fully smooth to one another.

Sometimes doing an initial larger radius fillet to smooth out one area of the model can then help to make the fillet generation easier in the original area - surfaces that are smooth to one another are easier to fillet because the fillet surfaces meet up directly and don't have as difficult of a corner juncture to have to be figured out.

Like for example in your case here, rounding off this edge here with a larger radius:





Will then make this area actually easier to fillet after that:






Another area to watch out for is fillets can easily fail if they just don't fit within the given area, especially when things are at sharp angles to one another fillets will want to eat away a lot of space and if they try to eat away an entire face or edge that will cause them to fail too.

Filleting is definitely a finicky area in MoI, it's a lot harder problem than what it might seem like to get different kinds of corner junctures handled well.

- Michael

Hi Warren,

> Actually, you know what? Maybe the problems I'm having are inherent to how I'm building things.
> I'm, by force of habit, building the larger shapes and then trying to fillet everything at the end
> that needs it. Is it better to fillet as I go along? Maybe that's less stress on the calculation engine?

Well, it sort of depends - ideally you would actually wait until the end like you have been doing, so that's not "wrong" to do that.

But if you have the possibility to reduce edge topology complexity (reduce the number of edges all colliding at any one single point), or smooth out a broad area of the model with a larger fillet or sometimes by just incorporating some rounded shapes into the initial profiles, it can be good to do that so that you avoid getting into difficult to handle fillets later on. That kind of takes some experience to sort of proactively plan for filleting in advance like that.

- Michael

SO GOOD, thank you! That worked. I'll try to keep that in mind in the future then. Now I want to dive back in and see what I can get away with. :P

Thanks a ton for your awesome replies! You're really going above and beyond here and I appreciate it.

Random question : Are the bolded lines important in terms of how easily one will be able to work with the mesh? Like, should I be trying to hide those behind other geometry when possible or anything like that? Or are they purely decorative?

Hi Warren, you're welcome!

> Random question : Are the bolded lines important in terms of how easily one will be able to work with
> the mesh? Like, should I be trying to hide those behind other geometry when possible or anything like
> that? Or are they purely decorative?

Well, they're not exactly decorative - they're a normal part of the NURBS geometry. The way NURBS objects work is you have a bunch of surfaces and those surfaces have "trimming boundaries" on them that define which areas of the surface are active and which part of the surface are holes or cut away portions.

When you do boolean operations the actual "underlying surfaces" stay the same and only new trimming boundaries are created that then trim away more parts of the surface area.

Those bolded lines are the edges of your model, the edges are what make up the trimming boundaries.

It's a pretty different geometry system than a polygon mesh object, with a polygon mesh your object is made up of all little facet elements and there isn't this same concept of a bigger "underlying surface" and "trimming boundaries".

So it's not like you necessarily want to get rid of those, it's normal for your objects to be made up of various trimmed surfaces.

- Michael

You can also use some external free monster for capricious fillets in Moi like Fusion 360! ;)
And come back to Moi! ;)
(you can renew after the end of each year! ;)
https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/How-to-get-a-Fusion-360-Enthusiast-license.html

Why not use a Variable Fillet for keep the original "sharp edge" before the last Fillet? ;)
Of course here you must make that in 2 passes due the little angle of some edges as shown above posts!



Don't press Done after the first Fillet(s) here 25° before make the Variable Fillet(s) of 0° of the 2 points on the right of the yellow "curve line"!
You can make and erase any number of different Variable Fillet(s) on the same curve(s) first selected as long as you are not exit of the Fillet function!

Variable Fillets are a little tricky but with a little training that is very easy and powerful! :)



Here a general last Fillet of 5° for example!


And careful for the second Point of the Variable Fillet of the Back faces of your ob!ject!
Maybe a zoom must be made because you have very near closed points!!!
So the Variable Fillet (s) or normal Fillet will be not work on the bad point!