EDITS ARE LISTED AT THE BOTTOM!!
Comments are greatly appreciated!
This is a remix of @ktapper's lovely Duet Maestro Case. It was inspired by @Ajlockhart's "Extra Vents" case.
Although they're both nice, neither addressed the airflow properly, IMHO, so I reworked it.
A BIG shoutout to @ktapper for supplying the original CAD file in his post so I didn't have to wrestle with editing a mesh file!! :-)
- Smoothed the airflow in the intake vent (front) to reduce turbulence.
- Added vents on the side for better cooling of the main board area.
- Added a second wall to direct most of the intake air under the drivers, the only part of the board that really needs cooling.
- Reworked the original wall to allow a path out to the exhaust fan. This should cause most of the air to flow smoothly front to rear under the drivers.
- Enlarged the front & rear vents a bit.
I haven't printed this yet! I did slice it in Cura 4.0 and it looked fine, long print with .2 Layer & .4 nozzle (over 10 hours) due to the details. I'd use .6 nozzle and .4 layer (Still over 5 hours).
There is a lid posted in the Comments section of the original by @ktapper:
I intend to post a lid of my own design for this soon.
THIS IS DESIGNED TO WORK WITH A LID!
Not having one will significantly impact the airflow!
I'll state right here I'm NOT an airflow engineer, but have had Heat Transfer & Fluid Flow training in the US Navy Nuclear Power program (MANY years ago, LOL!) so I have some instinctual understanding of it.
As I see it (without some smoke tests to be sure), the major airflow is from front fan to rear fan across the drivers. A secondary air flow will move from the vents across the board to the exhaust (partially driven by the suction the primary airflow path creates). The upper front vent hole also helps.
Just as an aside, the Maestro works fine with just air cooling unless your bed is being driven by the Maestro (not controlled externally by MOSFET or SSR) and exceeds 14 amps (per @DC42, the designer ...). If you're running near the edge of the Duet's 18A limit on the bed, the bed's driver (back right corner by the bed connectors) might run hot with this design.
Although two 40mm fans don't move much air, together they should handle it fine unless you're really driving the board with NEMA 23's, two extruders and a bed all running controlled by the Duet.
Even then it should be fine, but if not, you might look into hosting a Wind Turbine ... :-)
Comments welcome, but I don't always get back here frequently (it's on and off) so cut me some slack if I fail to respond to you, I'm NOT ignoring you ;-) !!
I have printed this now. Had a tangle on the filament near the end so came out crappy :-)
That said, there were a number of places for improvement.
Air holes on front, right, and back sides are completely reworked. In particular, this should give better flow to the bed driver.
The wall inside the front fan did not print properly, so I reverted it to a mostly flat piece.
The walls were thicker than needed and were not optimized for slicing at .4 (or .6) layers, so I thinned them out.
Made other minor cleanups and ran it through NetFabb repair to ensure no silly errors.
- Curu's support system is pretty broken, even in the new 4.0, so I did a version with supports in Meshmixer and baked them in. It's listed as WITH SUPPORTS. As of now I haven't printed it, will post back when I do, but you have two versions to play with.
The reworked model is showing 4hr 31min for print time in Cura 4 with .6 Nozzle & .4 Layers. I have the speed cranked up to 70mm/sec with 40mm/sec on most other items, so using a standard 60mm/sec with others defaulted gives 5:19, just to give you a baseline.
After printing again with changes (used eSun PLA+, .6 Nozzle, .4 Layers, 2 Walls 20% Infill)
I discovered a problem (remember, this is a remix).
The screw holes for the fans were too big! I reduced them to 2.75mm which should allow tapping (or just screwing in) 3mm screws.
I also reviewed a concern expressed on the Duet forums about the airflow. If you click "Thingiview" on the picture you can rotate the object (left click & hold).
You'll see there's a small divider wall inside the front (angled) fan. If you peek through the hole you'll see the air flows under the wall into the air channel below the board.
I considered enlarging that hole but it can't be changed, since it would then blow OVER the PCB, not under the drivers.
Some concern had been expressed about the airflow being low, which I addressed above
Another solution, if you still have concerns about this, is to use bigger fans
One possibility: a 40mm blower (on front fan port)with adapter like this: https://www.thingiverse.com/thing:891740
or even 50mm blower on the front with an adapter like this: https://www.thingiverse.com/thing:2719213
There's some more discussion of fans in Post Printing section below.