Illustrator :: Allow User To Control Size Of Halftone Dots

"Can Illustrator allow the user to control the size of halftone dots?" Just to be clear, for silk screen, the dots must be course. I have read several posts on the subject and still there is no definitive answer. The PPD file has been loaded. The document is a CMYK. In the print menu the separation menu has only very fine settings available (The lowest is 56 lpi/300dpi) which if selected makes very little to no difference in the dot patterns.
 
Just to reduce confusion, often a silk screen printer will try to get two colors for the price of one. The simplest example would be to get Black & Gray with one screen. If I set the Gray to 50% and the Black to 100%, still no change. If I use spot colors like PMS Cool Gray and Black, no change. Moving the files into Photoshop may work but fundamentally speaking PhotoShop in my opinion is for constant tone images or Photos, and it seems counter productive to add in a extra step (and software) to the work flow.
 
I like Illustrator and have invested hundreds of hours learning and promoting it's virtues. When I was asked by a local shop how to do this task, I responded,Can I do this or do I need to tell my associate to keep using CorelDraw! 7...