Burrman or Michael,

This should be fairly straight forward, but I don't really understand why the filleting feature is failing here. Any ideas?

Also, more valuable would be HOW YOU GO ABOUT UNDERSTANDING THE PROBLEM. Not looking just to fix this part, but rather how better to diagnose. Thanks!



https://altuit.cloud/web/dbpub/3D/filletproblem.3dm

Hi Chipp, usually my first step is to examine the "side walls" where the fillets are ending - dealing with how the fillet ends is frequently a problem area.

In your case here I notice that the "side wall" on the top is not just a simple plane surface (which is easiest for the filleter to deal with), it's a kind of wider surface. Having that did simplify topology but at the expense of not having a simple plane surface where there could be one.

If you go ahead and delete the top surface of the piece entirely (copy it to the clipboard first), just leaving a hole there, then the fillet that you want to do will succeed and then after you have done the fillet you can paste the old surface back in and rejoin it, and then fill in the hole that the fillet opened up using Construct > Planar.

So for that particular fillet that you wanted to do, it would have probably been better for that top surface to be segmented into multiple faces so that there could be a simple plane surface where the fillet ended, it looks like the place where the filleter is getting tripped up is something to do with handling the end of the fillet running into that top surface.

- Michael

Hi Chipp, also if you look closely at the top surface you can see that it has a bit of an undulating wave to it:



That kind of undulation is the type of artifact that often results from fitting one single curve that runs through a curvature discontinuity like you'll get at a juncture between a line and and arc. If that was the result of using the Rebuild command you could try using a tighter tolerance value like 0.001 units instead of only 0.01 units, which would reduce the undulations. But keeping it as separate arc and line pieces would give the most accuracy and keep the top to be a simple plane... It would also introduce more edges which makes for a more complex topology too though which may cause other problems later on at junctures where you've got a whole lot of edges coming out from one single vertex.

- Michael

Hi Chipp, so I think it mainly has to do with the undulations in the top surface being a bit too pronounced, here's a version where I just squished flat a wide region of the surface's control points and that also makes filleting behave better.

- Michael

Thanks Michael,

I was able to fix the problem by separating the surfaces, filleting, then combining and planar to 'seal' the solid.

That said, I didn't understand how you were able to 'flatten' the control points? Can you elaborate? It sounds like a helpful skill to have. Thanks!

Hi Chipp,

re:
> That said, I didn't understand how you were able to 'flatten' the control points? Can you
> elaborate? It sounds like a helpful skill to have. Thanks!

That was by surface control point editing. First select the top face and use Edit > Separate to break it off into an individual surface object.

Then I used Edit > Show pts to turn on control points, and selected the middle set of points about like this:



Then go to an elevation view like the Back or Right viewports, and use the edit frame to flatten the points using "flat snap". That's where you grab the corner sizing grip and drag it downwards until you see the "flat" snap point engage, like in this example here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3378.4

If you don't get any flat snap it means the thing was already flat, that's a way to test for planarity. Also it can sometimes be of diagnostic use to do the opposite and drag the corner sizing grip outwards to stretch it and amplify the wiggles to get a better idea where they are.

Hope that helps!

- Michael