Improved Chamber Cooler / Barrel Cooler | 6015 USB Fan

04/08/2025:

I was going to print a barrel cooler using the 5015 fan when I saw the 6015 fan was a little cheaper and flowed 50% more air (2.9cfm vs 4.5cfm)! That's a big jump for only 10mm growth in size. These 3D printer fans flow much more air than the MagnetoSpeed RifleKuhl (<1cfm, $70) and don't use expensive batteries that only last an hour or so. I have seen designs using the portable mattress air pumps, but they seem very loud, annoying, and don't last very long. For less than $30, you have enough material to make TWO barrel coolers that outperform the competition.

This design uses a single fan, 3/8" vinyl hose, and a printed hose barb to fit into the chamber. The chamber barb Outer Diameter (OD) is at 9mm, which is about 0.5mm smaller than a 223 case so it should fit most chambers. I recommend PLA+ minimum for the chamber barb, PETG or ABS are better. Typically, the chamber doesn't get as hot as the barrel. 

[I'm not responsible if you get melted plastic in your chamber!!!]

***Note: I used the Wathai brand fan; it is unknown if other brands have the exact same bolt hole pattern.***

I plug this fan into my old, portable Anker 20,000W USB charging bank. It only draws a maximum of 1.28W at full speed in my testing, and 252 mAh after 1 hour. It will last a LONG time:

20,000mAh bank: 80 hours

10,000mAh bank: 40 hours

5,000mAh bank: 20 hours

2,600mAh rechargeable AA Eneloop Pro: 10 hours 

At the range with my earplugs in, I can't even tell that it's on without looking at the fan spinning. I measured 51 dB at 1-foot distance. It definitely won't bother anyone around you or draw attention to yourself. I usually just leave the fan on and use it in-between shot strings.

BoM:

1. 6015 USB 5v Fan (I used Wathai) ~$14 for 2 pack
   1. Possible single fan alternative w/switch?: WDERAIR ~$10 (bolt pattern not checked)
2. 4x M4-0.70 x 25mm Bolts (#8-32 x 1" also work) ~$2.50
3. 4x M4x6wx4d Brass Inserts (#8-32 also work) ~$7 for 50 pack
4. 1 foot of 3/8 vinyl hose (local hardware store) ~$1
5. 1x small 4" Zip Tie
6. Optional 1x Inline USB Switch ~$8 for 3 pack (fan does come with a dual switch controller)

Printing:

1. Main Body - tree supports on build plate only for the hose barb; use 3 walls minimum for 0.4mm nozzle, 5 is better; 5 top/bottom layers; I prefer adaptive cubic infill.
2. Cover - no supports.
3. Flat Elbow - print vertically with brim as shown.
4. Angled Barb Elbows - print with a brim as oriented; no support needed; use enough walls for solid infill.
5. Straight Chamber Barb - no support needed if printed upright as presented; brim not required if you have a good bed.

Assembly:

1. Use a soldering iron with a proper tip to melt the threaded brass inserts into the main housing just below flush. Alternatively, purchase bolts that are slightly longer and use washers & nuts/cap nuts. The total thickness of the box is 1 inch/25.7mm, so 1-¼" or 30mm should work.
2. Place fan inside housing and route the cable through the notch. Use the small zip tie as a cable strain relief on the inside of the case. Get the zip tie nice and tight.
3. Align the cover and screw it on.
4. Enjoy your new barrel cooler!

Closing thoughts:

If someone makes this with the WDERAIR fan, please let me know if it fits!