Martin, Pawel & Neil's double axial fan shroud v6.2 for the Wanhao Duplicator 6
PARTS YOU WILL NEED:
You will need a total of five m3 cap head bolts (three 20mm and two or three 8-16mm), and two or possibly even three additional 24V 40mm axial fan (two for use in the actual double axial fan shroud mod and you may also need a third fan to be used/cannibalised for its parts, specifically the extra length of wire/cable it will provide so that the double fans can reach the fan power supply connector ontop of the extruder carriage of the D6. The wires on 40mm axial fans i purchased were too short and so i need to cannibalise lengths of wire from a third fan to make it work and i had luckily purchased a pack of five 40mm 24V axial fans so i have three spare to cannibalise as needed). And lastly, a print out of this double axial fan shroud. (You can use the three black coloured 20mm m3 cap head bolts that secure the stock D6 single fan+fan shroud in place that came with the printer, so that leaves you with just needing to acquire two or three 8-16mm m3 cap head bolts).
ABS is more heat resistant than PLA so it will always be advised over PLA. Though you can give it a try to see if it will work with your specific brand of PLA but ABS is the surest option.
HOW TO INSTALL:
More than likely, you will find that the 40mm axial fans you've purchased or that you had spare lying around won't work when plugged straight into the print cooling fan power connection at the top of the D6. The reason for this is that the wiring of the pins in the female power connector for the 40mm axial print cooling fan on the D6 are in reverse polarity as compared to the majority of (if not) all axial fans on the market. So in order to get an externally sourced axial fan to work with your D6, you will most likely need to reverse the wires around inside the male power connectors of the axial fans. Ordinarily you can pull each end of the axial fan wires out of their male power connectors and simply switch them around to solve this issue but that won't be necessary here since you'll need to perform soldering anyway to get two fans working on the same power feed, so you can just solder the wires in the reverse polarity needed so that they will work on the D6. Now, whilst every person i've spoken with whom has tried using alternative 40mm axial print cooling fans on their D6 has found that the polarity of the wires needed reversing in order for them to work on their D6, i think it would still be wise for each person to check for themselves whether the wires do indeed need reversing or not for any additional fans they purchase by simply plugging it into the fan power connector ontop of the D6 and turning on the cooling fans via the D6 LCD menu screen (via MAINTENANCE>ADVANCED>Set fan speed>increase to 100%) and seeing if it spins properly or not for a short duration. If it does not spin, turn off the fan speed on the LCD menu quickly and remove the fan (as there have been some reports of people purchasing 40mm axial fans with the wrong polarity and yet they partially/intermittently worked for a short time before shortly damaging something on their control boards due to the reversed polarity). If the externally bought fan does not spin as powerfully as the stock fan provided by wanhao for the d6, then perhaps the wires/pins in it's connector are indeed the wrong way around. But usually if the wires are wrong, the fan should not work at all (as was the case for me with the additional fans i purchased). Once you know the polarity needed for each fan, you can proceed onto the step of soldering the wires and connections up.
Once you know the correct polarity of the wires, simply snip the ends of each axial fan wire. Then snip a good 10cm of wire off the end of your third spare axial fan to be used for parts (10cm off the length of wire with the white coloured male power connection still attached from the third axial fan we are cannibalising for parts). Solder the two axial fan ends together and soldering on the additional 10cm length of wire will probably give you way more wire length then is needed but better to be safe than sorry later as when you come to cutting away sheaths of insulating plastic around the wires, you can accidentally damage and strip away the copper wire on the inside off as well and thus need to try again a few times but each time you do so, you end up reducing the available length of wire remaining, so it's better to be safe than sorry and have extra lengths of unnecessary wire to reach the top of the D6 power socket than it is to have to purchase another pack of axial fans unless you are really competent with this type of work, then go ahead and make the lengths just right the first time). Then, proceed to solder the ends of these two axial fans in parallel (i.e. red wires together and black wires together if both fans share the same wiring polarity). Then, solder these two newly joined ends of the axial fans to the 10cm length of wire with the power connector that you cannibalised from the unnecessary spare/third axial fan. If both fans require reverse polarity, then simply connect the red wire of the newly joined (via soldering) axial fans to the black wire of the 10cm length of wire and then do the same for the remaining wires (i.e. black to red). Now go plug it in and check to see if your dual axial fans work.
After confirming it works, you will want to wrap the soldered bits of wires with some electrical insulation tape to prevent them from accidentally touching and thus shorting the circuit (which is a big no, no). Then, install the double fans onto the printed double fan shroud using the assortment of m3 bolts (three 20mm and two or three 8-16mm). Look to the pictures attached as guidance (if needed) for how to assemble the mod. You won't need any m3 nuts (anymore) to secure any of the bolts to the shroud because the m3 bolt holes on the left side are now small enough for the bolt to thread itself into the shroud creating a tight and secure fit.
And that's all there is to it. Enjoy! :)