Thoughts on Smash Cooling?

[MountainStorm]

I've been thinking about how to get some cooling into my Dual Sidewinder Micro smash. I understand Smashed electronics are for comping, short runs, yada yada. Well I am also aware that even the comp guys are likely to run their rigs during shake down longer than a few minutes at a time. And for the rest of us casual crawlers a smash is a convenient sized package but has obvious problems with heat soak. Many of the better chassis barely have room for the electronics so running a pair of cased ESCs with sinks just isn't an option.

My thoughts on this are to develop a slim Smash optimized aluminum "I Sink" almost like the plastic FXR mount in the stock XR10 chassis. It seems to me that the weight of a solution would be negligible compared to the security and convenience of having semi cool ESCs.

For instance my buddy Spiitz has a temp probe on his RX and monitors his HH BRXL smash and it gets up to 160F right away. It idles at 140F. So he is constantly stopping to let his rig cool down. I am sure most of us are pushing well past that temp with no probe and no real notion of how hot our stuff is getting.

The sink I am visualizing is a chunk of aluminum "I" beam with the PCBs attached with Ceramic Thermal Adhesive to either side of the upright and a pair of small finned sinks stuck on the outside of each PCB and one more on the top of the "I" beam section.

Nothing huge...just as tall as the PCBs are wide (maybe 25-30mm) and only as long as the PCBs (maybe 45-50mm). Thin gauge...1/16"...just enough to let the heat move through it and dissipate into the finned sinks.

I've been cooling hot blooded electronics for about 10 year now and there are even more elegant solutions (like heat pipes) and of course itty bitty fans...but I figure anything is better than wrapping the hottest stuff we run in plastic and shoving it as far out of the air stream as possible

What do you guys think?

[Calderwood]

I fail to understand why smashes have become so popular. Sticking the ESCs to each other and then wrapping them in insulation just doesn't make sense to me. They don't need to be against each other and they don't even need a full covering of insulation. Smashes seem to me like a problem rather than a solution.

[SilmarilS]

Any cooling solution is better than no cooling!

[SkaldidDog]

I de-smashed and went back to heat sinks. Cooler electronics perform better.

J

[MountainStorm]

Glad to know I am not alone in wondering about all this stuff.

I fully intend to test out my idea. I just want to see if I can make the whole thing small and light...compared to running two cased ESCs. Sometimes I tend to over think and over engineer things...so I am waiting for my common sense to kick in before I cut the heat shrink off these babies.

[Master Basher]

a pair of decased mmp with the heat sink left on, the heat sinks can be pushed into each other a slight amount for a small footprint and be placed sideways so that the heat may rise up out of it.

[tapped-out]

I'm thinking of trying these




http://www.ebaypa.com/albums/20140007/sku123674-12-.jpg


Details about 5Pcs Copper Heat Sink Laptop GPU CPU Heat sink Pad Shim 20mmx20mm 0.3/0.8/1.2mm from ebay.

5pcs Copper Heat Sink Laptop GPU CPU Heatsink Pad Shim 20mmx20mm 0 3 0 8 1 2mm | eBay

not sure how good they will work but worth a try.

[ROWDY RACING]

Swapping my heat stroked SW micros for Micro pros, the heatsinks should prove valuable.

[MountainStorm]

The stuff I like to use for gluing on heat sinks is a non conductive epoxy that passes heat from the part to the sink with no fear of shorts and the potential for potting the whole thing to make it waterproof. Arctic Silver Aata 5g Arctic Alumina 5g Thermal Adhesive Epoxy Set | eBay

I know copper is awesome at conducting heat (so is Sterling Silver) but the weight is too much IMO. Some finned aluminum heatsinks would be my choice. Dirt cheap from China Aluminum Cooling Fin Heat Sink for LED Power Memory Chip IC 40mm 40mm 11mm | eBay

[Trubble]

I just replaced both my Micro Sidewinders, but I doubt I'll be going back to a smashed setup. I do want to get in there and re-route some wires, though.

I picked up some flat steel (.08 x .250, I think) and cut them down to just shy of an inch long. My thought was to lay them across the back of the FETs when I re-install the shrink wrap. I'd like to do both sides of each, but I don't know if I can get the solder point for the positive wire small enough / don't know if it'll even cause a problem if the heat sink touches that point. Didn't figure it would be anything revolutionary, just a small 'something is better than nothing' gesture.

I had also had the idea for a couple of blocks (material unimportant) maybe 1.500" wide by 2ish inches long with two channels milled into them. I figured I'd remove the shrink-wrap from both ESCs and set the edges of the PC boards in the grooves and then they'd be stacked like books on a bookshelf. Then with no wrap on each ESC, but just one piece around the whole kaboodle, they'd be separated a little bit and able to shed some heat from at least one side. Make the blocks wide enough and the shrink-wrap doesn't even need to touch the ESCs, they can shed heat off both sides. I was going to ask if anyone knew if one side got hotter than the other, but it doesn't look to me like it matters much. Any opinions?

Or, I may just not go smash, and put 'em in wherever I can find room. The stock XR chassis doesn't look like it's got much room in it, so I may use the Ringer II chassis for the MOA, and take advantage of the open spaces it has. Sounds like a good 'over-winter' project.









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[MountainStorm]

I know Wisconsin and cooling won't be a problem for you in a few months...

The idea you have about mounting them in slots like shelves is something I tumbled around in my head too. A small fan forcing air through the gap would probably be as effective as using sinks with no fan. Where I crawl it can get dirty and dusty...there is crud in the smash trapped under the shrink...I can just imagine what blowing a fan would do for getting that grit all over the ESCs...which is why I am leaning toward a waterproof passive cooling solution.

[Master Basher]

Steel is a horrible choice for a heat sink.

Originally Posted by Trubble

I just replaced both my Micro Sidewinders, but I doubt I'll be going back to a smashed setup. I do want to get in there and re-route some wires, though.

I picked up some flat steel (.08 x .250, I think) and cut them down to just shy of an inch long. My thought was to lay them across the back of the FETs when I re-install the shrink wrap. I'd like to do both sides of each, but I don't know if I can get the solder point for the positive wire small enough / don't know if it'll even cause a problem if the heat sink touches that point. Didn't figure it would be anything revolutionary, just a small 'something is better than nothing' gesture.

I had also had the idea for a couple of blocks (material unimportant) maybe 1.500" wide by 2ish inches long with two channels milled into them. I figured I'd remove the shrink-wrap from both ESCs and set the edges of the PC boards in the grooves and then they'd be stacked like books on a bookshelf. Then with no wrap on each ESC, but just one piece around the whole kaboodle, they'd be separated a little bit and able to shed some heat from at least one side. Make the blocks wide enough and the shrink-wrap doesn't even need to touch the ESCs, they can shed heat off both sides. I was going to ask if anyone knew if one side got hotter than the other, but it doesn't look to me like it matters much. Any opinions?

Or, I may just not go smash, and put 'em in wherever I can find room. The stock XR chassis doesn't look like it's got much room in it, so I may use the Ringer II chassis for the MOA, and take advantage of the open spaces it has. Sounds like a good 'over-winter' project.









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[Dostradamas]

That is a good point.

Aluminum would be much better choice.

Believe it or not Titanium would even worse than steel.

Thermal Conductivity of Metals

[MountainStorm]

Originally Posted by Dostradamas

That is a good point.

Aluminum would be much better choice.

Believe it or not Titanium would even worse than steel.

Thermal Conductivity of Metals

As I observed when cutting and sanding Ti rod. Only the cut portion woud get hot...the rest of the rod would stay room temp...very strange.

If money is no object Sterling Silver would be awesome for heat sinks. I owned a "rare" Storm water block produced in the late 90's by pioneer water cooling guru Stew Forster that was Sterling....what a piece of work. Jet impingement technology.

Copper is next on the list and most good PC heat sinks are copper where it counts (heat density greatest) and aluminum where space permits (fin array). I anyone wants to see state of the art cooling they only need to do some cursory research on PC heat sinks from 2000 to 2010...they went from little aluminum grids with tiny fans to giant complicated heat pipe arrangements with massive fin arrays using multiple large fans.

One of the crazier notions I have is to use phase change (heat pipes) to wick heat from the electronics to a little "radiator" of fins placed behind NACA style ducting. I was thinking of this for a Vorza type 6s basher...our crawlers move a little to slow to be pushing air through a radiator lol...and have no room for fancy pipes and fin arrays

Although liquid cooled MOA motors would be fun to look at...wrap some small OD soft copper tubing around each motor...or maybe Holmes Hobby could machine water jackets into the cans

[BC-Brian]

Thing you need to worry about with a smash and heatsinks is shorting them out. I think trying to get some air out is a great idea though, just have to be careful how you do it.

Forced cooling typically does a lot more than passive cooling. You could find a small 20mm fan and design a smash mount for it. A fan would go a lot further for cooling the electronics and probably weigh less than a heatsink. pickup the 5V line from the onboard BEC and power it that way. A little fan should not have much impact on runtime. Make it super easy to remove so you can take it out when you are doing a comp run if you want.

just my $0.02

[MountainStorm]

I think you are onto something there.

[BC-Brian]

Originally Posted by MountainStorm

I think you are onto something there.

Maybe I am onto something.

20mm x 20mm, 4.5 grams, .1A draw @5V 1.2CFM and only $8

Sweet Fan Action

[Trubble]

Originally Posted by MountainStorm

As I observed when cutting and sanding Ti rod. Only the cut portion woud get hot...the rest of the rod would stay room temp...very strange.

......Copper is next on the list......

Once in a great while we'd get a customer at work that would need some copper fabbed up. Finding some nibs of 3/4" solid copper rod in the scrap bins was a rare treat. I don't think we've had a copper job come through this year, though.
And as soon as that stuff even so much as touched a deburring wheel, the whole thing was instantly too hot to hold. I don't have any machining capabilities at home, so they really weren't of much value to me.
Now and then I'll have the wife see if she can pick up some small scraps of .125" AL sheet. Kinda limited in how small of parts I can have her make, though, as the big shear she uses at work isn't really up to the task of making small enough of strips to make micro-sized heatsinks.

So while the steel is FAR from ideal as a material, it was a) available, and b) in the size/profile I could use. But to be honest, I'm kinda likin' that stacking idea. I think that may get looked into this winter.

[Ohioskills]

Originally Posted by BC-Brian

Maybe I am onto something.

20mm x 20mm, 4.5 grams, .1A draw @5V 1.2CFM and only $8

Sweet Fan Action

thats the same place for brushless motor senser plugs

[BC-Brian]

Yea, DigiKey has a bunch of stuff.

I am thinking that you could 3d print a tray that holds the smash and the fan to blow on both units. Use a Servo wire passthrough to power the fan whenever the speedos are plugged in. should still have plenty left to fire up the receiver if you don't happen to have a BEC.