Sorry guys I am stuck again on my motor mount.

I have a solid object - at least in the details box it says it is a solid.

However I want to shape one end of it to match the shape of the motor mount.

If I trim it using a curve, and delete the piece I don't want - the remaining part suddenly becomes hollow and reports itself as a set of open joined surfaces.

I have tried a simple line as well as the closed curve that outlines the motor plate. Both do the same thing. I have tried extruding the motor plate shape into a surface and then using trim and Boolean intersect. Same result.

I have read the documentation which shows both 3D and 2D intersections with solids producing a "carved" solid. It did work at the top end of the part. It doesn't at the bottom.

There is something about my solid that I don't understand. Can you help my understanding please. I attach a simplified model with the curve and straight line.

Thanks in advance

Hey wisty,

What you need here is merge (boolean command). Check out your line, there are two points in weird positions, if you inspect them (show points) you will see that your line has a portion that is "double", these points are folded. If you delete one of them (select and delete), merge command completes successfully here.

Let me know if this solves it!

Hi Wisty, yes the solid seems to be fine, it's that back-tracking loop in the cutting curve that is problematic like nameless shows.

Self intersecting areas like that will tend to mess up surface/surface intersections and volume based processing. The self intersection will make various kinds of containment algorithms to become ambiguous.

- Michael

Thanks. How do you spot something like that? Is there a "console" that reports errors etc, or is it simply a question of searching.

What confused me was that If I tried to trim the part with a simple straight line, I got the same effect.

Thanks again.

Hey wisty,

In this case, the indication for me was a subtle thicker line on that segment in viewport, that made me inspect closer and "show points". Overlapping lines or segments appear thicker/darker in MoI viewport, but it is subtle. For the Joined surface "degradation" of a solid without the user realizing, from what Michael has shared in posts here, I think he is considering a more direct notification system if something goes wrong or a solid becomes joined surface, but for now, the details window on top right is your friend.

In general, after some time with the program, you will start to have an idea of what the problem is most of the time. There are many informative posts (Michael's answers are nutshell encyclopedias usually) and video tutorials on youtube from several creators that show workflows and problem solving, when things get tricky. :)

Hi wisty,

> Thanks. How do you spot something like that? Is there a "console" that reports errors
> etc, or is it simply a question of searching.

There isn't any console for error checking as of yet, that is something that I do want to work on in the future though.


> What confused me was that If I tried to trim the part with a simple straight line, I got the same effect.

Well it is normal for the result of Trim to be surfaces instead of solids - Trim is a surface operation and cuts up just the surface skin of a solid or surface alike. It's the boolean commands that can work to preserve solids making "side walls" for cuts.

So using a line in boolean difference will produce the kind of result you want, Trim will break it from a solid into surfaces.

- Michael