Hi Jacobo, thanks for reporting this problem!

It appears to be a bug in Join. It may be a difficult for me to fix it right away, but it seems to be related to the small size of some of the pieces. Some bits are around 0.003 units in size.

A lot of small edges around this size to be joined tends to confuse the joiner, it seems to get some edges reversed. The joiner comes from the geometry library that I'm using, it's not actually in my own code that's why it is not too easy for me to fix it immediately.

However, there is an easy work-around in this case - scale everything up by 100 times before you join it. That seems to avoid the problem area of Join and makes it work properly.

To scale, after you import the IGES file, select everything and run Transform / Scale. At the "Pick origin point" prompt, you can just type in 0 [enter] for the origin, and then type in 100 [enter] for the scale factor.

After you have joined the scaled up objects, you can then create a mesh without those problems you showed. You can also scale back down after the join if you want.

So this scaling-up trick is something that you can try if you see this problem again and the model seems to be pretty small in size.

- Michael