I’m having trouble with one edge on a 3D model of a house key. The last thing I do before outputting an OBJ file is to bevel all of the edges. There is one particular edge that I don’t want beveled or at least not as much as the others.



I’ve had to modify this edge to get it to be filleted successfully. I’m not happy with it. The curved surface of the channel should meet the front surface of the key with a nearly sharp edge. In a perfect world the edge would still have a very small bevel on it. Any ideas on how this can be accomplished?

I’ve included the scene files. One before boolean and filleting and one after.

Hi Randy, so kind of the regular way to leave an edge sharp is to not fillet it. To do something like that you could select the edges that you wanted to leave sharp, then go push the Select > Invert button to flip the selection to all the other edges before running the Fillet command.

Was the fillet not successful when trying that? Sometimes leaving some edges unfilleted can make pieces kind of join up awkwardly.

Another way you could move forward is to just remove the fillet surfaces from that area where you don't want a rounded fillet, and instead model in some surfaces that have the shape that you do want to have there.

I've attached a version that is somewhat prepped for that, I deleted the fillets in those areas, and I drew in some line segments like this:



and trimmed the outer surface with those lines to kind of make a sharp squared off corner in those spots, is that a step towards the kind of shape you want? If so then the next steps would be to figure out what kind of a shape you want in the area that is now an empty hole and construct some surfaces to fill in that area using some tools like Loft or Sweep.

- Michael

Hi Randy, so one other thing that I'm not quite sure if I understand is if you're sure you want this little kind of ledge left by the cutting object here (the one outlined in yellow):



Do you possibly want something more like this? :





On that example the cutting object has a kind of outward swoop to it so that when it cuts it doesn't leave a little ledge or shelf in there...

- Michael

Hi, michael. Yes, ideally there would be no shelf like you modeled on your second reply. I added the shelf so it would fillet. Can you fillet the second one? I've had no luck filleting my key when I model that way. Thanks for your help!

Randy

Randy, I don't think you can fillet that with the fillet command, but you might be able to create some custom surface manually that fills things in there. I had to do with the light cycle model I'm working.

Yes, a custom surface seems necessary. I’m struggling because I know how I would fix it in a polygon modeler. Wish I could grab some points. I’m not sure how to get that nice sweeping surface to join with the face of the key but still retain the fillet on the other edges.

Hello,

I could do this with SCE. I defeatured the area first and then actually filleted the bottom joint and refilleted the sides. I couldn't get this to fillet correctly in MoI, and have to depend on other apps to make up for my lack of skill. Even at that I'm not sure of the quality of that corner fillet.

Hi Randy,

> Can you fillet the second one?

Yeah, a simple case like that seems to fillet, I've attached an example file.

It fillets at radius = 0.3 for example but you can kind of see how it's having some problems with putting in corner patches between some of the pieces. Those problems may have been even worse in your case.

If you leave the top edge unselected when you do the fillet it doesn't make for quite as difficult of a corner areas to patch in:





- Michael

Hi Randy,

> I’m not sure how to get that nice sweeping surface to join with
> the face of the key but still retain the fillet on the other edges.

Maybe something like this - since it sounds like the rest of the model is already set up how you want, it's probably easiest to do some surgery just in the localized area of it instead of trying to redo everything.

So that little shelf is kind of interfering with what I think is the kind of sloped shape you actually want so I deleted it, and put in a new sloped surface by drawing a curve here: (viewed here from the underside of the model with the back surfaces hidden)



And then extruding it:




Then I drew in a couple of lines and used those lines and also the edge of that extruded surface as cutting objects in the Trim command to trim that surface like this:



So if I understand correctly, this is a lot closer to the shape you want - a lot of times you may want to kind of get some bigger pieces set up the way you want and then take a look at what is going on with the surrounding areas.

One way to fill in the surrounding areas is to do a sweep.

To do that, select these edges and use Edit > Join to make a new curve that goes across all of them:



Now select that curve that was just created and also the top edge - these will be used as the profile curves for sweep:




Now run the Sweep command, select these side edges as the rails (I used the merge command to merge together 2 edge fragments on one side into 1 single edge but you could also use join for that as well):




So that will build a fill-in piece that takes the shapes at the ends of the fillets and slides them along those side rails while gradually flattening them into the end shape, it produces a result like this:



Is that close to what you were looking for?

The 3DM model file of that result is attached.

- Michael