Quaker City Grinding Mill 4. Choice of 4B Plates for fine grinding or 4CS Plates for coarse grinding. Choice of Tooth Feed for dry grinding or Worm Feed for wet or oily grinding. The QCG 4E Electric Disk Grinding Mill is used in fine testing labs around the world. The 4E electric grinding mill head construction is made of sturdy, durable cast iron. Free consultation 40 years of industry ...