Suppliers

http://www.conveyco.co.uk/

http://www.screw-conveyors.co.uk/

http://www.ajax.co.uk/feeders.htm#

http://wwww.guttridge.co.uk/product.php?id=16

http://www.dowsongroup.com/screw/conveyors.asp

Mathematics of archimedes screw

http://www.cs.drexel.edu/~crorres/screw/screw.pdf