Hello! I try learn MOI and have some issue....I make a wheel and I need to union two solid elements and Union doesn't work for some reason.....
I don't have open surface or bad edges and it still not work.....




Can some one explain why?...

I can't get it to work here either. But it does work in Rhino.
cheers,
eric

Hi Igor,

if you scale your solids, so that they are smaller, it should work.



Regards
Stefan

it's strange no ?

Hi Igor,

re:
> Can some one explain why?...

It's most likely due to some kind of bug, I'll put it on my list to investigate. It doesn't seem to be a bug in the intersection process though because both Construct > Curve > Isect and Edit > Trim seem to be working fine.

Since Trim is working ok you can use that to complete your model instead.

To do that, select both objects, and run the Edit > Trim command. At the first prompt where it asks you to select cutting objects or push Done for a "mutual trim" just right-click or push Done to indicate the objects will be cutting each other. Then at the next prompt where it asks you to pick which pieces to remove, switch to Mode = "Keep" and click on the 2 large main pieces. That tells it that you're going to keep the big pieces and discard all the little ones. You can then right-click or push Done to finish the Trim command. Then select the 2 pieces and use Edit > Join to glue them together.

- Michael

Hi, Igor.
The problem is the star. See screenshots. The solution is to replace the rear surface or change the guide.
Vladimir.

Thanks Vladimir, yup it looks like that's the problem area.

@Igor - the back of the star looks like a surface of revolution where the revolve profile was slightly out of alignment with the revolve axis. This has made a small area there in the center where the surface crosses over itself and self-intersecting surfaces like that will tend to confuse boolean operations. The object doesn't have a well defined inner and outer region when there is a self intersection in it.

Also since that back surface seems to be planar it would be better for it to be a plane surface rather than a surface of revolution. MoI's revolve command will try to replace things like that with planes but maybe it wasn't able to do that because of the misalignment.

Some quick steps to repair it - select the back face of the star and delete it. Then select the star object and run Construct > Planar - that will build a plane end cap and join it in and then you can do a boolean union ok after that.

- Michael

Thank you Vladimir! It is works!
Thank you all for help! Very friendly community!:)