How to create those anti-slip on watch crown?

I tried to create some cutting tools and perform boolean difference but failed. I cannot find any problem with the model, any hints?watchcrown.3dm (2.5 MB)

extend the edge of the surface, create a pipe, radius as desired (0.12) ,array polar the pìpes (40 or more) , boolean difference (delete input)
Filletedge (select all the ones created along , try different radius)

Hi Hungwai Lim,

Assuming you want to subtract the red objects from the crown with Boolean Difference, you need to make them all closed for this to work (ie they need to be solids).

In this case you can select them all and use Cap Planar Surfaces to close them. After this the Boolean will work.


Yes after Cap Planar Surfaces, Boolean Difference works!

Thanks a lot!