New Easier To Print
It has been TOO LONG in the making, but I have finished an update to the duct work that should solve some of the printing problems that some folks have had with it. It still has good structural form to hold it shape when printing, but now it requires much less bridging to get the print done. You still need to flip it 180 on the X or Y, and print with support from the bed only.
Dual Fan Version
And after promising enough people I would do it, I have done it. There is a dual fan version of the duct and a mounting brace included now. It adds a second 4010 fan. This does not mean I think you need it. In fact I think the single fan version with an upgraded fan is a much better upgrade because of less weight on the print head. However, for those that want more fans Tada! Note the small pegs on the mount line up with the access holes for the linear rod bearings, and there is a little cutout on the inside face that is just the right size for a small 3M Command Strip to fix the brace in place. Good luck, and I would love to see this installed on your printer.
I have seen several dual fan blower assemblies for the Monoprice Ultimate / Wanhao D6, but the all seem to add unnecessary weight. This model is based on some of the ring ducts seen on other printers / extruders. It seems to do a good job without the extra weight.
The one modification I might make would be to slightly increase the diameter of the duct to give the heater block a bit more clearance so that you do not have to print it in ABS (in PLA the heat can cause the outer edge to sag and collide with your prints). Otherwise I am pretty happy with this part.
I have added a new design that increases the ring diameter to 70mm from 60mm. It turns out my concerns about the ring sagging and colliding with the prints were well founded after a couple of days of use. The larger design in PLA is continuing to work well even after a few days of use. The smaller diameter design is still available for those of you willing to print in higher temp material and who want the closer air flow. I continue to be pretty happy with this part.
A third design has been added. This one provides a full ring and a more square-ish ring profile. Both of these features are intended (and are working) to make the ring more stable when things get hot and keep the duct from drooping into the print. Also, to provide a larger cooling area, I removed the directional vents and added lots more outlets. This lets the unit cool an area much larger than just the point of extrusion and seems to work much better.
I will be grateful for your feedback and suggestions.
A quick update is in order. A couple of Thingiverse folks have commented that this part is better when printed "upside down." They are absolutely correct. Turn this over so the fan port is oriented down in your slicer to reduce the amount of support required and to improve the overall print results. Thanks EasySt and others who pointed this out. Your feedback is appreciated.