Granite Best motor cooling fan for Granite 3s.

[GaGranite]

My cooling fan on my 3s stopped working and it didn’t last long. What’s the best upgraded motor cooling fan for the 3s?

 

[dure16]

I'm a big fan of the cheap "rocket" fans on amazon

 

[Glitch]

I'm using YSIDO 30mm from aliexpress it reaches without the extender but pretty tight.

 

[GaGranite]

Do they screw right onto the Arrma heat sink?

 

[SrC]

Just get a 40x40x10 Rocket alloy fan like @dure16 stated and use a Fan mount only. Pretty much plug and play.
Toss that stocker Heat sink altogether. It is useless. Air blowing directly at the motor is best. Faster, more sustained cooling results . My temp gun doesn't lie.
A motor's alloy Can is already a Heat sink by design. A Heat sink is just Bling, and keeps the motor from cooling faster. What matters most is fast thermal transfer. Why add even more metal mass of a Heat sink to cool down?? They don't even fit precisely enough to motors. In theory it works. Just not in practice.
Want even more cooling, just run doubles of this fan with a double fan mount or 2 single fan mounts, one for each, Space, Clearance and Length of motor permitting.
>>>A heat sink alone without ANY fan could offer a slight benefit over having nothing at all.
Then it seems easy enough to simply mount a fan to a HS. I get it. Arrma does that as many other brands do.
It's just far from the best setup at all.

 

[Hector_Fisher]

To summarize:

You can buy upgrade "replacements" like the rocket fans and mount them on to the stock heat sink, same location. This may very slightly improve performance.
Or
You can ditch the stock heatsink all together, which is not very good anyway, and buy a fan mount and fan (size of your choice) having the fan blow directly across the motor for better performance.

 

[GaGranite]

What is a good fan mount to place the fan on top of the motor?

 

[Surchaufeur]

Just get a 40x40x10 Rocket alloy fan like @dure16 stated and use a Fan mount only. Pretty much plug and play.
Toss that stocker Heat sink altogether. It is useless. Air blowing directly at the motor is best. Faster, more sustained cooling results . My temp gun doesn't lie.
A motor's alloy Can is already a Heat sink by design. A Heat sink is just Bling, and keeps the motor from cooling faster. What matters most is fast thermal transfer. Why add even more metal mass of a Heat sink to cool down?? They don't even fit precisely enough to motors. In theory it works. Just not in practice.
Want even more cooling, just run doubles of this fan with a double fan mount or 2 single fan mounts, one for each, Space, Clearance and Length of motor permitting.
>>>A heat sink alone without ANY fan could offer a slight benefit over having nothing at all.
Then it seems easy enough to simply mount a fan to a HS. I get it. Arrma does that as many other brands do.
It's just far from the best setup at all.

Interesting. But would that apply to cpu chips then? Its metal on metal. How i see the heatsink is it pull the heat from the motor and is quickly cooled down by the surface area of thr fins

What is a good fan mount to place the fan on top of the motor?

That is a good question

 

[SrC]

I built custom PC's many times. The CPU is "perfectly ground Flat" as is the Heat sink's Flat surface, and uses a Thermal compound for rapid thermal heat transfer. CPU's have HUGE a HS Mass and Huge fans by comparison to the actual size of and surface area of a CPU.
These RC motors are round and not precision ground including the HS that merely "Clips" onto it. So the surface contact areas are poorly matched. They are cheap. Thermal Transfer is horrible. So that much heat remains in the motor for longer and not completely drawn away by by the HS.
I even tried PC $thermal Silver paste compounds$ on HS and motors and such. It can work to a very limited extent. Just that once I deleted the HS , it was apparent that cooling is way better. Just need very good fans. All evaluated by my temp gun. A bare Motor can cools quicker. Heatsinks become heat soaked, so fans offer a slower cool down, having to deal with more Mass.
Pro racers use motor fans but never with Heat sinks. Their electrics are pushed to the limits.
ESC Thermal cuts and overheated motors for them is a DNF Fail. With Overheated Motors, Braking fades when the Magnets get too hot . Sometimes irreversibly so..
Just some food for thought in the big scope of things.

 

[Hector_Fisher]

Interesting. But would that apply to cpu chips then? Its metal on metal. How i see the heatsink is it pull the heat from the motor and is quickly cooled down by the surface area of thr fins

That is a good question

That's a more nuanced discussion than we're getting into here unfortunately. Heat is spread through contact (conduction, or touching between two solid pieces) and convection (fluid like air or water moving across a surface). Convection is better over larger surface areas, which is why CPUs use a heatsink to effectively increase area, but they also have to use a thermal interface medium (thermal compound) between the CPU and heatsink in order provide the best conduction heat transfer. Metal to metal is not a good way to conduct heat, which is why the arrma heatsink is not the best option. You could make it better by using some sort of thermal pad, but that's another discussion for another day.

What is a good fan mount to place the fan on top of the motor?

Something like this works fine.
https://www.amazon.com/NHX-Aluminum-Cooling-Motors-30x30mm/dp/B0BKR2MSDT/
Or if you're patient, you can order something like this from aliexpress and save some money.
https://www.aliexpress.us/item/3256802649751439.html

 

[SrC]

If you already have a HS and fan setup in place already, and have some CPU thermal paste floating around to try , like I stated above, this will help with cooling a slight bit, from my experience. Thermal pads don't work. Been there. Not effective enough for rapid thermal transfer to the HS. A thermal paste Adhesive might be best, if anything.
I would not intentionally design my cooling solution from scratch in this way, using a HS.

 

[Neelis]

I am really happy with my 50mm fans, 3d printed bracket and 36mm clamps from aliexpress.

 

[GaGranite]

Good looking set up.