Hi Defonten, that will happen if the object being booleaned is not a closed solid. When you select it, what does the object type indicator in the upper right corner of the window say, does it say "Solid" or "Joined srf" ? If it doesn't say solid then that's the problem.

The boolean commands are oriented around working with solids, they decide which pieces to keep and which to discard based on what volume they are contained inside of. If you don't have a closed solid which makes a volume then it will prevent that aspect of the booleans from working and it will function more like a surface trimming operation.

You can use the script from here to locate the open areas:
http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2

If you need more help could you post the 3DM model file of your object before doing the boolean so I could take a look at it?

Also you don't specifically say which command you are using, is it Boolean Difference or are you possibly using Edit > Trim instead?

- Michael

Hi Michael,

I sent you my model in PM. Also I'm attaching a picture where I tried to fillet an edge of a Solid but it gives completely detached fillet instead..
For modeling this I was mainly using Boolean - Diff and was slicing my mesh to pieces projecting various lines and curves onto mesh and doing Boolean -Merge. Is there a way to close hollow gaps of this model?

Hi Defonten, I'll check out your model shortly.

re:
> Also I'm attaching a picture where I tried to fillet an edge of a Solid but it gives completely detached fillet instead..

That means that the fillet engine was not able to trim the solid to make space for the fillet. When that happens but fillet surfaces were able to be generated, those surfaces will still be output so you can have a chance to use them and possibly trim some space manually to get them in place.

It's pretty difficult to guess at why it's behaving like that from just looking at the screenshot though, it helps a lot if you are able to send the .3dm model file as well with questions like these. My best guess is that it looks like you've got a previous fillet of equal or smaller radius that you're trying to make this new fillet also pass through. That tends to be a difficult calculation because a large fillet that tries to go around a smaller radius bend will have a type of bunching effect like this:



- Michael

Hi Defonten, I took a look at your model. It's a mixture of some open surfaces and some solids. If you hide the solids and leave only the open surfaces (you can do this by going to the "Types" section of the scene browser and clicking the eye icon on the "Solids" entry there), you'll see these are the open surfaces:


These pieces all appear to touch each other edge-to-edge so this is possibly the result of running Edit > Separate on something?

You can select all them and use Edit > Join to glue them together at their touching edges. If you then run the script from the link above you'll see there is still an open edge here:



So the bottom surfaces appear to be missing.

- Michael

Thanks for the quick answer Michael!

Ok.. but why can't I fillet edges of a solid like on a screen attached? It just creates separate filleted mesh which is completely detached from this solid. Thanks in advance.

Hi Defonten, please see my answer above for that part:
http://moi3d.com/forum/index.php?webtag=MOI&msg=8352.4

- Michael

Ok, thanks a lot. I will take a deeper look at my model then.

Ok, I checked this Solid with open surface Script - it's clean. I did Edit -> Join. And selected only one edge absolutely clean edge between two other edges - and it still creates separate geo not doing fillet at all. Ok, obviously there are some unseen errors in geo - is there a way to check for those other than just Edit-> Join?

Since you have the model can I pls ask you to try filleting one edge of this solid? You will exp. it yourself and will have a clearer picture. Thanks!

Hi Defonten, I don't think you have any errors in your objects, you're just running into filleting bugs especially for the case of fillets needing to be trimmed against each other.

You might try importing it into a different CAD program which has a more robust fillet engine like ViaCAD or OnShape.

To do it in MoI you'd have a better shot if some faces were combined together, like if this area here was just one face instead of many:



That then simplifies the fillet structure by quite a bit:




The filleter tends to have more problems if you've got small edges, like you've got here due to the segmentation in 2 directions coming close to each other:



I'll PM you back the model that has the larger faces in it so you can test filleting with that.

I made the larger faces by extracting those faces using Edit > Separate, then did an "untrim" (http://moi3d.com/forum/index.php?webtag=MOI&msg=444.4) by selecting all the edges of those faces and hitting delete to remove the trim boundaries and recover the full underlying surfaces, then joined the top edges of those to get back to the original generator curve for those extrusions, then ran the Rebuild command (http://moi3d.com/3.0/docs/moi_command_reference10.htm#rebuild) to fuse those segments together into a single segment curve, then extruded that into the one single face and used Edit > Trim to trim that against the edge curves of the main face followed by Edit > Join.

- Michael

Thanks a lot Michael, but could you pls clear this untrimming process up a bit more for me? I try to get rid of those edges and they're just won't be deleted. What am I doing wrong?

"You might try importing it into a different CAD program which has a more robust fillet engine like ViaCAD or OnShape."


I also had similar problem but also often running in some fillet issues mostly not wanting to
fillet at all not because of bad model but the fillet just don't want to do it's thing + it can be very slow.

When i saw how fillet works in Fusion360, it's just unbelievable what it can handle like "t-sections" or self intersections to name some.

I really hope that Fillet is on the priority list of Moi3D v4.0 - to make it way more robust and fast as possible.

Hi Defonten,

> Thanks a lot Michael, but could you pls clear this untrimming process up a bit more for me? I try to
> get rid of those edges and they're just won't be deleted. What am I doing wrong?

You're probably selecting just one edge and hitting delete - instead you have to select an entire trimming boundary and then push delete. A quick way to select the entire boundary is to select one edge and then use Ctrl+A for select all.

If you have a version of this file with your original curves in them you used to boolean against you can just copy/paste that over instead of doing the untrim.

- Michael