Boolean union sees one item vanish why?

two closed surface objects, union them and the bolt head vanishes.

Not sure why.

BOLT 0.5inch head fail Boolean union.3dm (1.5 MB)


Hello - the parts are not all closed. use ShowEdges to check, or SelOpenPolysrf.


Hi Pascal,
you just beat me to it, i did that and see the sliver, now wondering how to fill it as its a 4 sided gap.
surface from 2 3 or 4 edge curves doesnt work , bulged result.


solved it dupedge, sweep2 and use point.

As this was a download I wish folk were more careful with their work.