This adapter allows you to fit a 60mm fan in place of the stock 40mm fan on the Wanhao Duplicator i3. It also allow you to tighten the whole extruder-motor assembly really well which is not possible with the bolts going through the fan. The adapter has ventilation holes which help to blow the hot air away from the heat sink and holes to keep your extruder wires cool if they're located behind the fan.
There is also a version without vent holes. Designed not to interfere with the belt or any other part of the printer. Fitted with the stock bolts to the heat block and motor, You'll need four normal fan screws to attach the new 60mm fan to the adapter to complete the assembly.
If by chance the new fan interferes with the X-axis stop switch remove more off the inside screw poles before assembling or print this spacer: http://www.thingiverse.com/thing:1448241
An ideal Fan cover for the 60mm fan is found here: http://www.thingiverse.com/thing:1655833
Prints with minimum supports