Fan duct for RepRapPro Mendel
by ambrop7, published
This piece is a fan mount/duct/nozzle for the RepRapPro Mendel with the updated x-carriage design. It mounts to a head slot next to a print head whose nozzle is to be cooled. The nozzle directs the air flow just below the extrusion point.
UPDATE: added a version which mounts opposide to the head, as opposed to next to it.
The fan mount is to be screwed the same way as a print head, though you should first put nuts into the hexagonal nut slots. Screw the fan directly into the plastic; because the holes are not very deep, you may have to cut the screws or add washers on top of the fan.
Print this in ABS, not PLA. If PLA is used, the nozzle will suffer from melting due to the proximity to the resistor wire, heater block and the heated bed.
I was having problems printing this using Slic3r; the bridges on the bottom (top) are not anchored properly and fall down. With Cura generated g-code the result is very nice; the part in the picture was printed at layer height 0.25mm with 0.5mm nozzle.
You may have to reduce the Y range of your printer, such that at Y=0 the bottom of the duct doesn't bump into the clips holding the bed together.
Make sure that the part is not too high, or it will rub into your print bed. The distance to consider here is from the top of the bed (when head is lowered to Z=0) to the bottom of the plastic where the fan mount will be screwed. This distance should be strictly more than the total height of the part. In the precompiled STL, this is 27.5mm. If you need to make the part lower, in the openscad source, adjust the total_height. You will also need to move the nozzle appropriately; to do that, adjust the Z (third) coordinate of tube_start and tube_end by the same amount in the opposite direction (since these two are negative, this means to adjust their absolute value in the same direction).
The tube_start and tube_end parameters define the starting position and the direction of the nozzle. The tube_end will ideally be a few millimeters below the extrusion point (so as not to cool the heater block too much). Note that tube_end only controls the direction of the nozzle, its length is defined by tube_length.
NOTE: Due to the use of a minkowski sum the recompilation will be very long (~30 minutes). You can greatly reduce that by changing the resolution of the sphere in the sum to something lesser than 12, though that will make the width of the duct walls more incorrect.