Ciao to everybody!
Nice to meet you all! I'm Arian and this is my first post!
I'm new to Moi (i'm using it just from few days...)
I'm doing my second model with Moi and i'm playing a little with surfaces but i'm having a lot of problem with fillets...a lot of time i'm not able to do fillets :( ...i'm really new to surface modelling and to Moi too so i've a lot to learn...so i'm asking to you if do you have some advices about fillets....probably (99% surely :D) i'm wrong something...
I've attached two pictures to show to you my problems....
Thanks in advance for any help and excuse me for my very poor english ;)
Ciao
Arian

Hi Arian, welcome to the forum!

Can you also please attach the 3DM model file so I can examine your object in more detail?

Also what fillet radius are you trying to use? The first thing to try is to use a smaller value, maybe going down by 1/10 in size each time.

One of the easiest things that can cause filleting problems is if you're asking for a fillet radius that is too large for the fillet to actually fit in the available space...

But there are also a whole lot of other kinds of things that can also cause problems as well, like geometry that bunches up into tight folds or has a mix of smooth and sharp areas along shared edges (smooth edges makes fillets disappear), and various other things.

It's hard just looking at a screenshot to know which of these various things you might be running into.

Also the geometry library that MoI uses can have difficulties handling certain kinds of corner patch situations where different edges come together requiring a complex juncture to be formed in between them. Some other CAD programs can handle a lot more corner situations more easily, so some people use other programs in combination with MoI to help with filleting, ViaCAD is good companion for that.

But if you can please post both your 3DM model file and also let me know what fillet radius you are trying to use, that would help to give you some more specific advice.

- Michael

Hi Michael!
Thanks to reply me so fast and of course I can attach my 3dm file ;)
Thanks in advance for your time :D
Arian

I've attached a zip of the 3dm file ;)

Hi Arian, it looks like there will probably be a lot of things to clean up in the model before it would have a chance to fillet very well. That's a lot of edges that you are asking about and it looks like there will be some simplification or fixing up to do in many of those areas. It will take me a while to review so many edges that you are asking about.

I started with just one particular edge out of the many that you had arrows pointing to, this one here:



There's some problems in the structure of the object in that surrounding area which is probably preventing the fillet from being able to be calculated correctly. Fillet is a rather sensitive operation that involves a lot of tricky calculcations, if there geometry is malformed it can make it much more difficult for the filleter to do a good job.

Some things that I noticed in this area, is that the side pieces are not joined to one another, there are 2 edges here with some gap space between them, rather than that being a unified "side wall":



Also down in this area here I saw this anomaly:



If you zoom in more closely you can get a better view of it:



That sort of strange disruption in a surface usually means the trimming boundary is malformed in some way, like it's criss-crossing over top of itself which will then mess up the sense of what's inside and what's outside the boundary. In this case zooming in even further reveals this bottom edge has a strange hook shape on the end of it:




I guess it may help to know how this area of the object was constructed, it can help if for example you build pieces from a shared common curve to make sure the pieces join together well after they're constructed. If you have pieces that are constructed by only using curves on one side and leaving the other side to kind of wiggle around that can make for this kind of slight deviations between shapes at what you want to be unified edges, and then when joining together things that are sort of close to each other it can make pinching or awkward forms at juncture areas.

So probably these pieces need to be reconstructed to not have these problems before it will be possible to get a fillet on something that is in that same area of the model.

I hope this gives you some idea of what to look for. Later on today I can check out some other area of the model to try and give you some feedback about other areas. It might help if you could indicate just one particular edge to discuss next...

- Michael

Hi Arian, another kind of problem area in general is having sort of "stressed" surfaces that are bunched or compressed in awkward ways.

There's one such surface here:




Note that the surface looks somewhat irregular in it's shaded appearance? It means the surface has a kind of lumpy quality to it rather than being a nice smooth simple surface.

Usually to get high quality surfaces you need to make the surface to a more regular simple 4 sided outline. If you try to directly build a surface to an irregular outline with pieces pinching down or one side a lot longer than the other, etc... it will make for a stressed surface and later on when you try to fillet it, the filleter will be going crazy trying to track along teeny tiny little bumps in the surface.

So generally instead of trying to build surfaces directly to fill in an irregular boundary, you instead need to build larger more extended surfaces to start with, something say that extends more out into this area here:



Then use cutting operations (either Edit > Trim if you're working at an individual surface level, or booleans if you're working with solids which can save time if you're able to keep things as solids more throughout the process) to slice off some parts to form the final shape, rather than trying to build individual surfaces to the final boundary in every single spot.

So for example something like this type of big broad cutting surface to slice off the ends of the extended shape:


That's not quite exactly right, just a very quick example to hopefully give you the idea.

If you can form more pieces by cutting operations especially with many pieces cut by a common surface or also constructed from a common edge it will make for a much better quality model both with better alignment between pieces and also smoother and higher quality surfaces that are not stressed by trying to be initially constructed in a stressed way.

Hope this makes sense on some things you might try for a better overall approach!

- Michael

Thank you very much for the detailed explanation :)
I'll work on it!
Now i'm modelling a brake caliper (i'll open a thread too) and i'm following your advices from the beginning.....and i'm working better! :)
Then I'll try to doing again my mouse!
Thanks Michael!