Boolean Modifier Mesh Geometry

I'm trying to make a shower drain and am using a Boolean modifier into a very flat cylinder. I was able to get the circles where I wanted them, but the geometry is weird. When I add a subdivision surface modifier, it gets all messed up. I've been trying to dissolve edges, and re-mesh but I just can't figure out what to do now. And frankly, I don't really understand the root of this problem. Any thoughts?

Thanks!

• – Duarte Farrajota Ramos Sep 23 '18 at 23:50
• Possible duplicate of Boolean modifier combined with Subsurf modifier creates weird shapes. How to Fix? – Duarte Farrajota Ramos Sep 23 '18 at 23:59
• – Duarte Farrajota Ramos Sep 24 '18 at 0:04
• could you please share your file? – moonboots Sep 24 '18 at 9:19
• The reason for weird result are Ngons which are made by Boolean. When just cut out they look badly because of smooth shading though they still keep the original form, but with Subsurf the model goes crazy as Subsurf isn't really suitting wit Ngons, especially in these complex cases. Try to select all Ngons at once, then inset them with I. Then tringulate only Ngons (for quick and dirty solution) – Mr Zak Sep 24 '18 at 11:36