New to MoI 3D, but *really* loving it. Quite a simple problem: I cannot fillet this shape.

I'm not even mad, I just want to know how to solve this problem. I have attached the .3dm file below.

Hi cjwidd, what areas are you trying to fillet?

One thing that would give it a better chance for filleting is if your model was constructed out of more simple pieces, for example this surface here is planar but instead of it being a simple 4 point surface plane that's trimmed, it instead has a whole ton of surface control points:





It looks like you may be trying to start your model by getting 3D edge curves in place and then building surfaces from those - instead with NURBS modeling you want to try and construct as much of your model as you can by using 2D curves directly rather than patching in surfaces between 3d curves. See here for some tips for people coming from a poly modeling background: http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

- Michael

Hi cjwidd, so the other thing that can help to simplify your model is if your original profile curves didn't have unnecessary segmentation in them. For example this area here, instead of having several segments to this part of the profile curve you would want to have just one single line across that entire area:



That will also help with filleting later on a lot - filleting will be calculated along that face structure and if you have multiple faces it means more work for the filleter and also it tends to not like it when you have 2 coplanar pieces next to each other rather than one single larger plane.

- Michael

Hi cjwidd, so here's how I would recommend constructing your shape to get better quality geometry which will help with filleting.

So to start with your base profile curve should be as simplified as possible - every piece of the profile that is in the shape of a straight line should just be a simple 2 point line curve and not a lot of smaller segmented pieces:



Then use Construct > Extrude with "Both sides" option to make your base shape:



Now you want to use the other profiles you've drawn in the Top view:



Select your extruded piece and run Construct > Boolean > Difference, then select your 2 top-view profiles as the cutting objects.

That will slice your extrusion up into 3 pieces, discard the outer pieces and you'll be left with your result:



So notice there how the whole process was driven by 2d profile curves, and the final curved edges are a result of doing a boolean with the first solid against another 2D profile curve. That's usually the best way to do things, you don't want to try to build the 3D curved edges first and try to patch things between those piece by piece for mechanical parts, that's something that you'd only use for more semi-organic shapes that aren't well defined by 2D profile curves.

So then with this cleaned up result you should be able to fillet it although another fillet "gotcha" is that it can be surprising how much space fillets eat away from the model when curving pieces are involved. For your case here you will only be able to go to a maximum of 0.04 units before fillets in this area of the model will start to run into each other and cause the fillet to fail:





So you might want to leave the little circle out and cut that out with another boolean after you've done a larger radius fillet across everything else.

Hope this helps!

- Michael

So after Michael gave you a good "how to model it, here is a video of fixing your solid to fillet easier, if you are "receiving" solids like this......



You'll see me cut the end piece off and do it separately. Michael points out reasons for issues there....

Thank you so much for your help! I had seen different comments of this issue wherein polygon modelers seem to have a hard time reprogramming their thinking to better leverage NURBS modeling.

I took your advice and tried approaching the shape differently. I redrew the curves based on the silhouette of the object, and then boolean those curves into an oblong ellipse. You were right, and it worked this time (see attached). In fact, the 'nose' piece, that contains the rounded curve at the tip, was also causing some issues where the fillet was too large. Of course dialing down the size resolved this. Thanks again for your input (from the man himself no less (!)

WoW! I was busy trying to remodel that shape and noticed there were new responses. Really incredible support you all, thank you so much!

@BurrMan, I just watched your video and thank you for sharing. It was good to watch a more experienced user approach the problem from a different angle. I noticed your use of network to address a lot of the curves, good call.

No worries cj,

Michales response is the one to REALLY pay attention to for your future endeavors...

Peace out.