Lulzbot Mini Double Cooling Duct by jim2386

Last crawled date: 3 years, 1 month ago

UODATED 12/11/16 - Linked to a new 15mm blower. The original one, for whatever reason, wouldn't run at speeds below 100%. This new one has a much wider speed range. I've updated the STL files to match the new blower, which was slightly narrower than the original 15mm blower.
UPDATED 12/3/16 - Design complete! 15mm blower duct confirmed to fit and function as designed! Thanks BMEmike for building it!
If your printer needs a slight tweak in the design, please contact me.
UPDATED 11/30/16 - Fixed 15mm blower holder, downtube, and right and left duct to fit the 15mm blower. Thanks BMEmike!
UPDATED 11/28/16 - Added site link to smaller quantity heat inserts. Thanks BMEMike
UPDATED 11/20/16 - The ductright20mm and ductright15mm have both been updated to -2, I moved the nozzle away from the hot end by 3mm. It was just a bit too close for me. The down level nozzle will still work as it is in the exact same position as the stock nozzle. Please use the -2 from now on.
Added assembly images.
UPDATED 11/19/16 - Added (hopefully) helpful images showing the assembly process step-by-step.
Please read the entire description where I cover the details of this thing.
The Lulzbot Mini is a great printer. However, one of the areas where it can be improved is in the area of part cooling. The printer uses an axial fan, which are not very good and building air pressure behind a nozzle. The other issue is the cooling is only on one side of the part, which can lead to uneven looking prints depending on what side of the part is directly facing the fan.
This modification adds a second duct and a blower. This allows for much more efficient cooling. Both sides of the print are cooled at once and the airflow is much higher.
The modification uses the same holes and screws that are already attaching your stock cooling duct. However, you will need a few parts:
M2 heat inserts for reattaching the limits switch:https://www.mcmaster.com/#94180a307/=14zapiq
If bulk inserts aren't your thing, you can order them in smaller quantities here:https://itworks3d.com/product/metric-brass-heat-set-insert-plastics/
50x50x15mm blower:http://www.digikey.com/product-search/en?keywords=BFB0524HH
Note: This particular blower operates on the mini between M106 S40 and M106 S255. Tranlation: in your slicer, zero blower speed is 16% or less and full blower speed is 100%.
Note: I used a 50x50x20mm blower I had laying around my shop. Unfortunately is has been discontinued so I modified the thing to accept the 15mm blower. Since I have not tested the new blower, there's a chance we may need to modify the blower holder slightly. If you give this a try, please let me know if the blower doesn't fit. Do not assemble anything until you check to blower fit into the blower holder. It doesn't have to be a tight fit, but it shouldn't allow the blower to rattle around. Please contact me if modifications are needed. Thanks! Alternatively, you can design your own blower holder and attach it to the rest of the duct.
Please download the STL files for the blower size you use. When complete you should have the following files:
mount.stl (common)
cover.stl (common)
blowerholder15.stl
downtube15.stl
ductleft15.stl
ductright15.stl
or select the 20mm equivalent parts.
Do not mix 15mm and 20mm parts. Pick one set or the other.
Double note: On the part labeled "mount.stl" and "blowerholderxxmm.stl" there are two holes on the front about 2.7mm in diameter. Ream these out to 2.85mm diameter and use your filament in the holes to assure your blower holder is aligned with your mount when you start gluing (or acetone welding in my case).
NOTE ABOUT SUPPORT MATERIAL: All parts can be printed without supports EXCEPT "Downtubexxmm.stl". It requires minimal supports. Please see the image showing how to orient the parts on the bed to eliminate support material.
You can run the blower off the same wires that power the stock fan. You can either cut the wires and solder on the new blower or add your own reusable connector on the wires. Just make sure your blower is 24V.
WARNING! I've tested this design and, while the clearances are tight due to space constraints, my version worked perfectly. Please please please make sure the first time you try it you are ready to power the printer down just in case there is variation printer to printer.
Results: I've attached an overhang using the same Gcode model. One with the stock duct, one with the new duct and 20mm blower (only running at 50% speed, 12V right now). The improvement is quite good. I'll hopefully have it hooked to 24V in a few days.