Helix fan duct (customizable, parametric) for Anet A8 and the like

thingiverse

Why do all fan ducts suck? This one sucks less (I hope!). There are several reasons: first, it doesn't restrict air flow (each branch cross-section is 1/2 of the inlet). Second, it maintains laminar air flow. Third, it provides even cooling from both sides (good for PLA plastic). Fourth, it's completely customizable - just load it into FreeCAD 0.16 and edit variables in cf spreadsheet. Designed for Anet A8 (Hesine, Omni, etc), but you can change parameters to fit it almost anywhere. Use a heat shield. This fan duct cools the heat block a lot, so insulate it or use some kind of heat shield (I made one from cotton stripes and kapton tape). Look at the temperature graph: without a heat shield, temperature swings cause serious wobble that looks almost exactly like z-wobble, but wobbling disappears when a heat shield is installed. There's a gap between heatblock wires and duct's right branch - the heat shield fits there just fine. PID tuning: don't skip this step! After installation of fan duct run PID tuning as described here: http://reprap.org/wiki/PID_Tuning with fan running at your usual fan speed and save new parameters into your EEPROM (or, better, create various PID parameters for various plastics types and set them in gcode startup scripts). How to customize: use FreeCAD 0.16 (install from web, don't use stale versions from repos). Open freecad source file, switch to cf spreadsheet and edit variables. If FreeCAD is too slow to recompute on the fly, install Lattice2 extension, turn off recomputes, edit spreadsheet (look at the drawing for variable names), click recompute. Export helix_fan_duct_v7 object as STL. Note that S3D complains about self-intersecting surfaces - this is due to how FreeCAD handles helix objects, but it doesn't matter printing-wise. It will print okay. Printer: Anet A8. Rafts: no. Supports: yes. Resolution: 0.2. Notes: print it with "build plate only" supports, upright. Both Cura and S3D support that option. Stock Slic3r fails to slice it - Prusa's Slic3r does work. It's an easy print, done on my junky Anet A8 with stock fan duct. I used PLA plastic, it works okay for PLA printing with bed temperature about 65C and fan 100%. But bed temperature over 80C is too hot for PLA duct - use ABS or something like that.