We bought the brand new Limelight 3G for off season this year, and was initially impressed by its CNC body without noticing its fanless design like a MacBook. While we are tuning autonomous, it got so hot that the 3D printed PLA support kind of melted. I wander whether it’s common for 3Gs to go overheated, and if so how everybody address that issue?
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The 3g uses passive cooling somewhat similar to the new radios, I’d reccomend printing the Limelight mounts out of a more heat resistant material like ABS or PC
Also, like the new radios, mount the back to metal if possible so it can be a heatsink.
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At least the limelights have mounting holes. On the new radios it’s like “Mount this to metal… but also, your only attachment methods are VHB tape (which acts as an insulator) and Zip Ties (unsecure).”
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We ran 4 of the Limelight 3G on our bot this year and didn’t experience any sort of overheating as described. Our mounts were PLA+ if I recall correctly. (Later made of aluminum, but for rigidity, not due to overheating)
I would definitely be skeptical of PLA melting. How long was the robot running when you noticed this?
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but be careful because the limelight 3g electrically grounds to the case.
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How dare you besmirch the good name of Zip Ties! /s
I agree this does seem like a bit of a design flaw. I’m expecting to see third-party heatsink/mounting cases made by vendors this upcoming season or the year after that. It will become a problem eventually and I’m sure teams wouldn’t mind shelling out a little extra to ensure their radio doesn’t fly across the field.
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I believe by Champs, inspectors were aware of this and were not faulting teams for it. Otherwise yeah we covered our mounts in electrical tape.
What does this mean
I wouldn’t fault teams for it either (I wouldn’t blame them), but they would need to fix it so that they don’t electrical fault through their frame…
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On 3061, we used a combination of thermal tape and tie wraps with the hope of getting better thermal conductance from the radio to the robot structure for the new radios at Worlds.
Something along the lines of Amazon.com (though I think we used individual strips - when we made this call, we were in a hurry and went with what we could get the fastest).
Did it make a difference? All I can say is that it didn’t cause a problem and better thermal conductivity from a surface that the vendor is already telling you to heatsink can’t really be a bad thing…
We didn’t count on that tape for retaining the radio - it’s for heat transfer and not mechanical mounting - so we used zip ties as “recommended”. As @cbale2000 inferred, mounting holes would have been a nice option for secure mounting of the new radios.
Sounds like this might be a good practice for the Limelights as well.
Meaning failing inspection for it. My recommendation is just wrapping things in e tape (including all mounting holes).
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Ugh - say it ain’t so (though you just said it was and I believe you) - ugh.
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“for it”
for it existing on the robot as a case-grounded component, and therefore requiring it to be removed in order to compete? (seems unreasonable, not the first and won’t be the last case-grounded component)
Or for its mounting method resulting in grounding some frame components, and the team being kept out of match play until its taped up and the frame components are measured floating? (reasonable, I would do this as an RI)
To be clear, I’m pretty sure we’re violently agreeing, I’m just genuinely confused by the usage of “failing inspection” and whether you intend it as a permanent vs transitory state
Failing inspection is a transitory state, at least in my experience. I usually phrase it as “haven’t yet passed inspection” or “have some rework”.
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Passive heating and higher temperatures than you expect is not necessarily “overheating”. It very well could be in its design parameters, and unless it was thermal throttling with passive cooling it likely was within design parameters.
It’s just hotter than you expected. Add some thermal tape and mount it to something metal, or design a heatsinking case and you should be good to go!
I’ve had enough PLA parts succumb to heat deformation (sometimes when I left in the car) that I try to print parts like electronics cases or ones that are against mild heat sources out of PETG instead.
Well I’m sure the thermal environment then was also a factor. The occasion happened when the robot it running under like around 30+ deg Celsius with sunlight shot from windows above the field. I’d consider it some ‘extreme’ work environment for our bot colored in black if that’s really the case.
What did you guys do for mounting and heat dissipation?
We just used electrical tape, and nothing specific for heat dissipation. #8-32 bolts with heat shrink over the shank to isolate the mounting bolts from the case as well
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