Cooling Drum

Re: Photos - don't know 'why' they're distorted but, you get the idea...

Cooling roasted coffee beans quickly is an important part of the roasting process... This is how I cool them (can also be used to cool roasted nuts)

See below for Roasting info..

The Parts (refer to General Assembly cartoon):

3D-Print Parts:
For Manual Rotation
Drum-Drive (Hub) for the drum
(Manual Turn knob, if not purchased)

For Motorized Rotation - Also Print the following
Mount Parts (A & B)
SwingArm
GearDrum
GearDrive
Switch Mount
Battery Mount

Other Parts (as needed):
Manual Turn knob - use whatever you want that fits (including Drawer knobs, a chunk of wood or other printable’s... or a gear)

Spacers as needed for maintaining Drum and Gear position
Drum: “Zehui” brand
(I removed the Tabs on each side but, that’s my preference...)
Frame: 1-Inch (O.D.) PVC cut to desired size, 90º Elbows and Tee’s
Hopper: Cardboard Box cut and glued as needed
Axis Shaft: 1/4 Inch diameter Alum or Steel rod (from HomeDepot)
Spacers: Hollow tube (plastic, alum, steel...from HomeDepot)
Motor (if using): Nextrox 30RPM Mini Gear Motor, High Torque

Screws (motor mount, attach and hub), washers, Spring/RubberBand... etc
Self-tap screws or, Tap the threads (8-32) on gear boss
Battery or Power Supply
Wire and Toggle Switch (I was lazy and just used Jumper’s in prior photos)
(FYI- Sheet-Metal screws also work well as self-tapping screws)

Tips:
Make the stand as Large/Small as desired (provide room for a Bean and chaff tray).
Ensure hopper and tray do not impede drum rotation.
Install so drum’s door opens in usable position.
(Can drill small hole in the SwingArm and PVC and use a Nail or Cotter-Pin to hold spring.
This will enable pulling gear back for clearing gear engagement to manually rotate as needed)
Switch Wiring: If using a Switch, it's just a simple hook-up and suspect you'll figure it out...
(reversing +/- will rotate drum in opposite direction so, wire it for desired direction and consider how the drum's door will open...).
If Mounts rotate on PVC, shim with sandpaper or thin card-stock...

Printing: Printing Gears can be tricky, do some testing...
Gears: 2 Top, 2 Bottom Layers, 2 Shells.
(Note: I print gears with two processes - One for teeth and one (with 6 shells) for the Bosses that get thread-tapped. If not able to print in two-process, consider gluing gears on shaft after all is setup and working.)

The Motor (reference, not an endorsement)
https://www.amazon.com/Nextrox-30RPM-Electric-Motor-Torque/dp/B00O7IHVIA/ref=pd_cp_60_1/147-7670202-9355718?_encoding=UTF8&pd_rd_i=B00O7IHVIA&pd_rd_r=954f0bfa-9d61-4851-ba78-d0fd62168fd6&pd_rd_w=NT6TT&pd_rd_wg=WNmgD&pf_rd_p=ef4dc990-a9ca-4945-ae0b-f8d549198ed6&pf_rd_r=23CK7VRYKA6M0E0HZ9G5&psc=1&refRID=23CK7VRYKA6M0E0HZ9G5

The Drumr (reference, not an endorsement)
https://www.amazon.com/dp/B078RFYM4T/ref=psdc_13791161_t2_B01JRTRZNO

Roasting Info
If needing a Cooling Drum (such as in this post) then, perhaps you already roast beans or, are interested in doing it...

Don’t get hooked on the idea of needing a roaster that is useless, non-user friendly and a waste of money.

Start out simple by using a Hot-Air popcorn maker (watch some YouTube vid’s).

Then, consider buying a Bowl-Type (various brands), or a Fresh Roast. Avoid Behmor!!!

I have several different roasters and always, always prefer the Bowl type. Next favorite is my Fresh Roast (older model but still works great for small batches).

Though not endorsing any brand, my favorite for large batch (up to ≈ 1 lb) is
https://www.amazon.com/Household-Roaster-Durable-Electric-Roasting/dp/B07GX78398/ref=sr_1_5?crid=3S95CA8N2G3VF&keywords=coffee+roaster&qid=1569703355&sprefix=coffee+roas%2Caps%2C221&sr=8-5