Having tried and designed several dual fan mounting systems for the Wanhao D6, I came to the conclusion that all of them have their own problems and having to re-print the whole thing just to make small adjustments (or if the thing started to deform) was a pain. In my view the stock, right hand cooler isn't actually bad, it's just the lack of left and cooling that lets the printer down.
I've taken a different approach, retaining the stock cooling and designed a mount that is fixed using the unused M3 tapped holes in the head block. This provides a significantly more stable platform on which to mount the additional 40mm fan. The design also separates the mount from the fan shroud/nozzle so you can try different designs of nozzle or just re-print that part should the nozzle become deformed. The mount also allows for height adjustment so differing nozzle heights can be catered for.
The mount worked great. Rock solid and with zero deformation. I was however still having problems with the fan nozzle deforming when printing ABS. All the left hand side fan mounts suffer from this issue. They are fine when printing PLA, PETG and other filaments that extrude with a hot end temp of 200° C or under and a bed temperature of 60° C or less. When you ramp that up to 230/100° C the nozzles just start to get soft and deform, sometimes to the extent that the nozzle starts hitting the print with disastrous results.
It’s generally accepted that cooling isn’t required with ABS, so why not get the ‘warpy’ component out of the way? Obviously, having to undo bolts to remove the nozzle each time is a right old faff (believe me, after switching filament about 5 times in a week and doing this each time, I know!) so I have designed a nozzle to work with this mount that simply slides on and off. You just need to mount the fan with the two rear bolts only and slip the mount on from the front.
After some people reported issues with this mount fouling the left hand rods and preventing homing, I have modified the mount to remove additional material and increase clearance. I've included 2 STL's for the new mount, one with supports included, the other without.
Print with the base (fan mount plate) on the build plate.
Supports required for the mounting arms.
I removed the automatically generated supports from the screw mounting slots. The screw slots will probably need some filing - I made them quite tight.
Print in PETG or ABS.
Print with the base on the build plate. Supports required. Try and make sure the slide on 'ears' are supported as they need to be quite accurate. Removing supports from the nozzle opening can be a pain. Be patient to avoid damage!
Print in PETG or ABS.
You will need 4 x 5mm M3 Machine Screws to fix the mount to the block and 3 x 20mm M3 Machine Screws (2 if using the slide on nozzle) with nuts to mount the nozzle and fan. I've also used nylon washers but those are optional. If using the slide on nozzle, mount the bolts with the heads on the underside. The nozzle has clearance intended for the bolt heads and may not clear nuts (if you were to insert the bolts from the top).
You will also (obviously) need an additional 40mm fan and if this is the first mount you have created, do yourself a favour and replace the stock one at the same time with a ball-bearing fan. You will either need a 'Y' fan lead adapter or some soldering skills. The fans are wired in parallel but you MUST make sure the polarity is correct as it is reversed on the stock fan. There are more detailed wiring instructions available, check out the D6 Facebook Group: https://www.facebook.com/groups/470637449795481/
When fitting the mount, assemble the whole thing first and hand tighten the mounting screws. I would suggest using a steel rule or other straight edge to get the bottom level with the existing right hand nozzle.
Some people have reported issues slicing the slide on nozzle with Cura. I have no idea why this would be as it slices without any problems in S3D. To help out, I have included a PETG GCode file for the nozzle that has been tested on the D6.