I really wanted to be able to use Triffidhunter's parametric herringbone gears ( http://www.thingiverse.com/thing:10707 ) as recommended by Richrap, but they were just too tall to fit on my X-carriage. This adapter will raise the Wade's block by 2 mm which is just enough to allow the large gear to fit. Read more at http://mynext3dprinter.tumblr.comPrint the adapter and the herringbone gears. I had to trim my prototype to clear the X belt. The modified STL file should fit perfectly. Replace the old gears in the Mendel90 with shiny new ones. Don't forget to recalibrate your Z-height and E steps/mm.