Problems with Boolean failing

I’m experimenting with creating knurling but I was unable to union all of the individual pieces to subtract from the cylinder. It just said the union failed. So I resorted to subtracting them one by one. I can only get a few to work and then it either does not recognize the selection to subtract, fails or creates a totally misformed shape. Any idea how to do this? Why is it not working?

Not sure how to help you out with what you created and your current workflow. Here is a knurl I was playing with a few months ago. It consists of two variations.
And, here’s the Shapr3D file if it interests you.
Knurl.shapr (8.2 MB)