Improved hotend duct for Lulzbot Taz5. MUCH better cooling of the hotend. Cured PLA filament jams (grinding) as soon as I installed it. Uses a 25x25x10mm fan with a duct that surrounds the hotend instead of the small blower that is stock. Uses the same 2mm mounting screw as the stock fan.
This duct and fan keeps the upper section of the hotend cool and keeps the filament cool before it feeds into the heated section. Works like a champ!
We were having quite of bit of trouble with filament grinding (refused to feed, and jammed) especially with glow-in-the-dark PLA and metal-filled PLA. After a lot of experimentation, we discovered that we had what is called "heat creep" in the filament. The filament bulged slightly before it would melt and would get stuck in the hotend in the finned section. Very annoying. Countless ruined prints.
I modeled this duct after the E3D duct. The E3D hotend is longer and uses a similar duct, but the duct is also longer and uses a 30x30mm fan. I basically shrank the whole duct so it would use a 25x25mm fan and would fit the Taz Hexagon hotend.
Uses this "2510", 5 volt, 25x25x10mm muffin fan that I bought on Ebay:
Here is a similar fan (likely higher quality) on Digikey:
The fan holes in the duct are sized to allow 2mm screws to simply self-thread in. I had a supply of 4-40 screws, so I drilled (#43) and tapped the holes for the 4-40 screws I had and slightly enlarged the holes in the fan to accommodate.
It is a tiny part so you should set your printer for a medium to fine print. I made mine from Inova, but ABS would work as well. PLA or HIPS would likely soften or melt in use, but you could try it if that is what you have on hand.
Print with some sort of higher temperature filament, like ABS or Inova or Nvent or polyester copolymer.