what size screens for diamond z tub ginder

I would like to know what size screens to get for a diamond z 8000tkt. first grind was done with 4x6". We tried a progressive setup with a 1.5" first sceen and a 3x5 on the second screen for the 2nd grind, but Im not happy with the product. This setup makes an inconstant mulch. I would like a fairly fine mulch with nothing over 3". I think the 3x5 is allowing too big of material through.

What would be a good combination? I'm thinking progressive is not the way to go.

Thanks!

what size screens for diamond z tub ginder