RB3 Single Part Cooling Fan - Redux by DMCShep

Last crawled date: 3 years, 1 month ago

Adaptation of JP1's part cooling fan ductwork, designed to be easy to print and far sturdier so it's less failure prone.
Changes
Both bolt holes are 10% larger
Increases tolerance for bolts, which in my experience don't have to be super tight at all

Arm is thicker in Z and X axis (orientation described as installed in printer)
Alleviates over-torquing of fan mounting bolt from breaking the part at the mounting bolt

Arm starts at height zero as printed, so supports are not needed there
Main flat area now at height zero as printed, so supports are not needed there either
Last two items make for a FAR easier and visually appealing print

Inside fan lip thickened to 1.5 mm
Increased from original 1.0 mm, allows infill to strengthen area and prevent failures

Inside fan lip aligned with Z axis, rather than angled oddly, and also starts at height zero as printed
No supports needed until ridge occurs

Heavily cleaned up geometry that got murdered in STL export process
Blender file included to save any further remixes from major headaches

New in V2
After testing out my own design, two persistent issues cropped up: arm wobblyness and layer separation cracks, either on the arm itself or right where the bolt secures the fan. Both of these areas have been heavily fortified to ensure issues are no longer present. I did allow 1mm around the existing fan mount to ensure the exhaust square from centrifugal fans of irregular shapes will still fit fine in the print, however this won't affect structural integrity.
New in V3
Added support for Walter's low profile bearings, based on changes introduced in this adaptation
New in V4 [UNTESTED]
Adjusted M3 Bolt mounting area for better security (V3 changes made this a very loose fit. Highly advised to upgrade to V4 or stay on V2)
Outstanding issues

The hard stop on the fan ductwork doesn't want to use supports and requires manual cleanup after printing when using Simplify3D. May want to address this later, a gradual tapering might be a wiser choice than a hard edge given the fan seems to "chatter" against it if not secured well. A press-fit would likely fare better


Supports are still required on the arm due to the way I printed it, however if the arm remained level at Z height of zero, it would not be needed at all, and the fan would still fit correctly (I wasn't sure if this would work and played it safe to be cautious -- fan would readily fit fine if arm remained at zero Z height throughout) Fixed in v2

Mounting hole is still somewhat fragile and doesn't like torquing much. I may need to bump the Z down some more and thicken the area around the hole even further. Design fixed in V2, don't know how much torque it can handle however.
Recommendations

Print with supports. It shouldn't try to print any inside the ductwork itself, only in the bolt holes as well as the arm (and the fan lip if your slicer works that way)

PLA might melt being that close to the hot end, I printed this with PLA/PHA however which can withstand much hotter temperatures. Prior iterations with PLA/PHA have lasted a very long time
Changelog
2018-05-30
Initial Upload
2018-08-09 (v2)
Made arm print entirely on bed, rather than elevated, while allowing 1mm square cutout for fan should a thicker fan be used
Gave arm a triangular shape to stiffen greatly (reduces failures from layer cracks)
Lifted part off Z by 0.75mm and further completed semicircle around arm bolt hole to prevent cracks at hole
2018-10-25
Added pics comparing v1 and v2 (just noticed they were missing, sorry about that!!!)
While I was at it cleaned up verbage of changes for easier understanding too.
2019-02-20 (v3)
Made section touching bearing holder flush equally as recessed as section touching aluminum plate, to allow nearly any bearing holder to fit
Added remix source due to adapting geometry from a different JP1 design
Added pics of the comparisons
Fixed cover thumbnail
2019-03-10
Added a remix source since they randomly added a new source for the fan with a more relaxed license (CC-AT instead of CC-AT-SA).
2019-04-13
Fixed M3 mount bolt area -- no pics yet, should be self explanatory comparing STL's