Radix Heat sink

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Mr. Fring

Mr. Fring

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Location
South Florida
Corally RC's
  1. Radix
  2. Sketer
I installed this sink on the radix can... worked so well I don't think I even need a fan. It barely fits under the body but otherwise fit like a glove
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If it's loud, it's efficient! ;)

since the mot housing aren plain as e.g. surpass motors there is only a poor heat coupling between sink and motor housing.
So the sink may quite cool while the motor is boiling.
I'm using a fan just like @morrjr71 in exaclty this position, works out just fine…
 
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ol1ver said:
If it's loud, it's efficient! ;)

since the mot housing aren plain as e.g. surpass motors there is only a poor heat coupling between sink and motor housing.
So the sink may quite cool while the motor is boiling.
I'm using a fan just like @morrjr71 in exaclty this position, works out just fine…
Click to expand...

The sink seems to be extremely efficient at pulling heat out - instantaneous response... better than I would have guessed. Definitely keeping my motor 20 degrees cooler. It's also nice not having to worry about debris getting into a fan.

I'm wondering if it seems to work better in this particular model because the radix body has air inlets right in front of the motor. Seems like there must be a stream of air coming right thru to carry the heat away from the fins. Maybe if this inlet wasn't there it wouldn't work as well
 
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Question is:
where do you measure? The sink or the motor? I don't want to appear as as a smart *ss but the only value that is true is the one directly on the motor ant NOT the sink. Thermal grease can improve the efficiency of the heat sink -like it is done in most electronic devices- but that stuff is terribly disgusting and above that hazardous.
 
ol1ver said:
Question is:
where do you measure? The sink or the motor? I don't want to appear as as a smart *ss but the only value that is true is the one directly on the motor ant NOT the sink. Thermal grease can improve the efficiency of the heat sink -like it is done in most electronic devices- but that stuff is terribly disgusting and above that hazardous.
Click to expand...


I've used thermo paste and it's messy and I just don't see how much it would improve things when it's already quite good.

I measure at multiple points. Front ,rear and bottom of motor housing. I also measure sink at two points to see thr delta between it and the motor. Prior to installing the heat sink I measured the motor during at least 2 different runs on different surfaces. It's without a doubt making a difference.

I believe the air flow is entering and exiting like this and carrying heat with it as it passes by the tall fins

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Well, you definitely know what you're doing! (y) good to know a sink also works, but I might still prefer the fan.;)
 
Here's some temps from today... front of motor by pinion side was 145, sink was 147, and rear of motor was 147. So the sink is pulling heat. Without the sink I was pushing 165ish. I tried running without a body just as experiment and my temps actually dropped by 15 degrees. So perhaps a fan will improve the heat transfer because the extra wind flow really helped drop the temps even more
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Just as a comment - you have to be cautious when measuring temperatures with this kind of IR-thermometers. The measurement is heavily impacted by the type and color of the surface - the factor behind this is called the emissivity. Your model (as most of the budget ones) has a fixed emissivity factor of 0.95 which is a good compromise for many surfaces, but not for e.g. blank metals (like the heat sink). Therefore the measurements on the black motor surface should be ok (surface similar to carbon), but for the measurements of the heat sink I don't know how accurate they are. Here's some more detailed information:

Unbenannt.JPG


However, I agree that a heat sink does help significantly if there is enough air flow (especially your run without the body was a good test!).
I have seen similar results in the past (directly measured on the motor by using a thermocouple).
But at the end of the day, the simplest way is still to put your finger on the motor - as long as it doesn't hurt it is ok ;)
 
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I installed this setup to compare to the passive cooling system... these babies move some air! I'll take some measurements to see how it does against the sink.

 
Mr. Fring said:
I installed this setup to compare to the passive cooling system... these babies move some air! I'll take some measurements to see how it does against the sink.

Click to expand...
Those NHX heatsink and dual fans are awesome! I have one on my Traxxas MAXX and it works great. Just one piece of advice, put some spacers between the fans and the heatsink and the fans and the carbon protectors. Otherwise grass and stuff gets lodged in between the fans jamming them and breaking the fans. I speak from experience! Creating those gaps fixed the issue. I broke two fans before doing this mod. I bought aluminium spacers anodised to the same color so it looks great too.
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On my XTR I'm planning to put this heatsink and fans which is very similar, and I'm planning to do that same mod on them.

PS: You'll need longer screws too!!!
 
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