This is a tool and cutter grinding fixture designed for use with a shop bench grinder.  The design is by N.W Tinker, and I obtained the plans from Guy Lautard.  This tool allows you to do a surprising amount of tool sharpening with a minimum of tooling in your shop.  The most likely need is resharpening end mills.  It is designed with a mounting block which incorporates the end geometry of milling cutters - that is, primary and secondary end relief and the 1 degree or so depression towards the center which provides more tool life for the cutting corners.  The rod with ball handle in the center is actually marked as a gauge for setting height relative to the grinding wheel center for flute grinding.  My only modification from the original design is to change feed screw design to incorporate a micrometer-like setting (seen on the right).  This does make it easier when grinding a lot of material off a chipped cutter.  Although this is the barstock version, built partly from scrap, there is a larger (more robust) design built from castings which you can purchase from Guy Lautard's site.