I was so tired of sifting my crushings through hand held sieves that I broke down and tried this machine, I put it together and put my first 10 LBs of ground up ore in the top screen and turned it on and in less than 2 minutes it has separated all of the sand into two different sizes. Then I got to thinking and looking at the size of the screens that came with the unit. I then got a couple of my plastic screens that I had been using and they fit perfectly into the unit, now I can do seven different particle size custs, with the 2" screens from Keene, and they fit and worked perfectly.