Think I found a bug related to supports

[wrwindsor 0]

Picked up a STL of a phone stand from cults3d (dot) com with a drop-down overhang in the design.

 

Rotated it back 15 degrees to change where the supports drop down and the supports went away.

 

I think this pic tells the whole story.

[fvrmr 73]

Try changing your support overhang angle and see if that helps. 

[kayakbabe 12]

I think I would print that as two pieces and weld it together. I don't think you'd need any supports then.