Hello,
I have difficulty that stops my work.
I need to extrude bottom part for 2 more milimeters on the object attached.
Attached is original and extruded to see what has happened.

I tried to select the bottom side and extrude.
Also tied to make another object from copied bottom plane and do a boolean union with that object (also tried with 1mm overlap).

What happens is that every time I try one or more corner (filleted) walls will dissappear.

Also tried to mirror those walls from those that were left and join everything (also union) but it's clear it will not join.
I select the main objects (it says solid in description) but copied walls remain unselected.

I also tried with MoI v4 but it does almost same thing.

Any idea how to properly extrude this without artifacts?

Thanks a lot

Hi Mr. Yuri, it will take me some time to study and figure out why those fillets are disappearing, something seems to be messed up with them but I have not been able to determine exactly what yet.

In the meantime I have attached a file here where I've rebuilt those fillets by doing an extrusion from the bottom up, then trimming it and joining it. This version seems to behave properly now.

Hopefully that should solve your immediate problem and I'll put it on my list to investigate what is going on with your original model.

- Michael

Thanks a lot Michael

You're welcome! There does not appear to be anything wrong with the original fillets, I think it is a bug in boolean union between fillets when one of them has an extended "underlying surface" that goes a ways past the current trim boundaries and the second one is contained inside that extended underlying surface area.

I've been seeing the after effects of this bug for quite a while now but I didn't have a good way to reproduce it but I do now with your file. That should give me a good chance at fixing it.

- Michael

Hi Mr. Yuri, I've been able to track down the bug which was causing this - it is in boolean union where it is attempting to merge 2 cylinder surfaces into single larger cylinder but is making a wrong result when the 2 cylinders have opposite axis directions.

I've been trying to find this bug for quite a long time without success until now, I had thought it was a bug in filleting since all the cases where I've seen it have been on fillets. But until now I've only had examples of it after it has already gotten messed up which made it difficult to figure out.

Thank you for posting the file especially with the "before" and "after" states, it helps a lot to be able to repeat the problem instead of only seeing the end result. It will be very good to get it fixed up.

- Michael

I'm happy to help

whats interesting is that if you extrude the base upwards first to then reselect it and go down it works without a problem and stays solid












cheers
shayne

And maybe you can also use this by Max Smirnov for eliminate some lines contours...after the extrude...

http://moi3d.com/forum/index.php?webtag=MOI&msg=7912.4