How much heat do CO2 lasers generate?


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    Member SerMumble's Avatar
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    Default How much heat do CO2 lasers generate?

    Building or buying a laser is great and all but to get the maximum efficiency in power and longevity, the tube needs to be kept cool to room temperature and preferably a little below. Ice cubes in a water bucket is an ugly solution to me because of maintaining an ice cube supply and it stops being viable with laser tubes longer than 800mm. I do not trust CW-3000 or various water radiator/chillers for their high cost and noise and questionable internals. I would like to build my own water chiller and integrate it into the case of my laser. For that, I am looking at CPU AIO radiators, Peltier TEC 12709 cooling modules, and refrigerator copper tubing. That brings up the question: how much heat do CO2 laser tubes generate so I know how much cooling that I need?

    CPU AIO radiators are a quiet solution and at $11 a 120x240x30mm piece (I already own the other parts), I could get 4 of them and some cheap 120mm fans at low rpm's to cool the water like a conventional CW-3000 but without the noise. But are 4 radiators enough? Too many? Should I consider 6 or 8 AIO radiators? Without any method of quantifying thermals I'd be guessing in the dark and mis-accommodating the number of radiators needed in the build.

    Peltier TEC 12709 modules for around $3 plus some cooling towers and 12V 30A PSU's are an immediately cheap solution because while being very inefficient on their own. The benefit of TEC's over radiators is while radiators cool and warm water temperatures to room temperature, TEC's can push water temperatures below the room temperature and significantly so if so desired. This brings up a system of cooling water flowing out of a laser tube by the radiators and bringing that temperature back down to room temperature, then having the TEC's chill the water temperature below room temperature just before entering the tube. A simple Arduino, thermistor, and mosfet rig can regulate the system.

    4mm to 1/4" diameter copper tubing is pretty cheap for $20 you can get 50ft of tubing and with a hobby pipe bender, you can make really elegant tubing through the machine. A combination of plastic/rubber tubing and copper tubing can really let you control heat breaks in a system or make your own radiator if you are so bold.

    If anyone knows of the TDP or some unit for quantifying the heat a CO2 tube generates between 700mm up to 1500mm that would be a big help! Thanks!

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    Default Re: How much heat do CO2 lasers generate?

    I'm in the same boat; I've got a K40 that's in pieces pending installation of my Grbl-based controller. It's going to need a cooling solution...

    You can measure the maximum heat you need to dissipate by measuring the electrical power the machine pulls from the wall when the power output to the tube is turned up to the maximum. For making the measurement; I'd just temporally rig up a bucket with some ice water in it. One of those "kill-a-watt" meters comes in handy here if you don't have a clamp-on current meter or a convenient place to clamp it on.

    There will be some power that's pulled that never makes it to the laser tube which goes into inefficiency of the electronics; as well as some that goes into the optics transport motors; but this should give a ballpark figure to shoot for when sizing the radiators. If you have "too much" cooling capacity; you will just have better performance out of your laser; if you have too little, you'll cook your tube - so shooting high is a better idea than shooting low.





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    Member WayneHill's Avatar
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    Default Re: How much heat do CO2 lasers generate?

    Make a DIY cooler from an old refrigerator on Craigslist. Punch holes through the front door to avoid puncturing the coolant lines. (Not making that mistake again). Have the lines go into a series of cooling buckets inside the fridge. A CPU cooling is not enough for the "coolage" you require for a laser.

    Wayne Hill


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    Default Re: How much heat do CO2 lasers generate?

    Hmm good ideas, well, this is a half hearted crack at the numbers and I'll use an 800mm(~40W) laser tube for example:

    Working Voltage:15KV (Trigging Voltage=22KV)
    Working Current:18-22mA
    Efficiency of energy not turned into heat: 5-20%
    Factor of Safety: 2

    Calculating the highest amount of heat and energy the laser produces:
    P=IV so Power = 22mA * 22KV = (22*10^-3) * (22*10^3) = 484W .... hang on, wasn't this a 40W lasers? Oh well,

    484-(484*0.05) = 459.8W of joules/second which is roughly equal to 459.8W of heat generated/second

    30x120x240mm radiator with heat dissipation:
    No solid numbers but it's recommended one 120x120x30 radiator block with a fan per 200W as a rule of thumb cited by this mathmatical fellow username Lephron:
    https://forums.evga.com/Radiator-Rul...b-m437039.aspx

    The number is a bit high so I'm taking it with a grain of salt to maybe 150W per 120x120x30 radiator

    459.8/150 = 3.06533 so in theory double 120x240x30 radiators would be plenty

    If we include my factor of safety of 2, then we get (2*484-(484*0.05))/150= 6.292 which seven 120x120x30 radiators would be plenty or four 120x240x30 radiators. I hope my math makes sense even if it isn't professional.


    Also, this guy cooled his 80W laser with only 2 radiators


    Keep in mind I am constantly adding safety throughout my calculations and aren't even near the low voltage of a continuous load so maybe loading up 6 to 8 radiators is not a smart thing. I might even want to consider running only two radiators and one or two peltier modules as shown by this fellow:
    https://www.instructables.com/id/CO2...Water-Chiller/
    Who used two of the same modules for his 40W laser.

    Which gets me thinking what if I have two water cooling loops, one for the laser, the other for the peltier modules. I mean, the radiators would cost the same as fan towers and would take up less space in the laser. I'd also enjoy less noise while getting that sweet sweet below ambient water chilling. The options are a bit overwhelming.



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    Default Re: How much heat do CO2 lasers generate?

    As for cannibalizing a refrigerator, I will consider it, but not a clue how I could cram something like that in something the size of a K40 or glowforge laser, maybe I need to look in the mini fridge department but even at that point why I am not buying an industrial water chiller is a good question.



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    Default Re: How much heat do CO2 lasers generate?

    Quote Originally Posted by SerMumble View Post
    I am not buying an industrial water chiller is a good question.
    I have a 6040 60W Co2. You 'need' a water chillier for those Co2 for production (+60min operation time). If you just need to make one-cut on a Sunday afternoon then a bucket filled with cold water and an aquarium pump is sufficient really.



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    Default Re: How much heat do CO2 lasers generate?

    Quote Originally Posted by Mecanix View Post
    You 'need' a water chillier for those Co2 for production (+60min operation time). If you just need to make one-cut on a Sunday afternoon then a bucket filled with cold water and an aquarium pump is sufficient really.
    That's really good advice, what type of chiller and temperature do you chill to for reference? As for the quote, out of context. [The reason why I would buy a fridge and why] I am not buying an industrial water chiller is a good question. Run on sentences are confusing and a bad habit of mine.



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    Default Re: How much heat do CO2 lasers generate?

    Quote Originally Posted by SerMumble View Post
    That's really good advice, what type of chiller and temperature do you chill to for reference? As for the quote, out of context. [The reason why I would buy a fridge and why] I am not buying an industrial water chiller is a good question. Run on sentences are confusing and a bad habit of mine.
    I simply use a 1/16HP water chiller (CE certified) which was designed for aquarium, a side container for the distilled water and a small pump. Inexpensive kit (<$300 for the whole kit if memory serves correctly). Temperature is set to 18dC, not-super-cold but not-too-hot (near room temp); meant to avoid thermal stress on the tube. Works perfectly fine for the type of cutting I do.

    You could also fabricate that thermoelectric cooler as per your initial idea although I personally wouldn't go that route as this may end up being unreliable and adding-up a(nother) potential hazard. Mind you I have no experience/knowledge with it (only assumptions). If you end up cracking on this idea let us know how it all worked out.



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    Default Re: How much heat do CO2 lasers generate?

    I simply use a 1/16HP water chiller (CE certified)
    Which one? Got a link?



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    Default Re: How much heat do CO2 lasers generate?

    Quote Originally Posted by __Britt View Post
    Which one? Got a link?
    I don't, even if I had that mfg would need to pay me to carry out their FREE online marketing. You trying to make me appear as a chiller shiller? ;-)
    Picked it up from my local specialized aquarium supply store, so is the pump, tubing, clips and the container. All fishy-happy stuff...
    Any type of water chiller would do the trick I'm pretty sure.



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    Default Re: How much heat do CO2 lasers generate?

    You trying to make me appear as a chiller shiller? ;-)
    I dunno, man... that cooler deal seems kinda fishy to me, if ya' know what I mean...

    Any type of water chiller would do the trick I'm pretty sure.
    Well, if it's an actual heat pump with the requisite tons of cooling (er... considering the load... pounds of cooling? kilograms of cooling?), and not just a fancy radiator... yeah. Just a radiator won't work here in the summer - the ambient temp gets too high, even with the AC running.

    The ones on Amazon seemed to fall into two categories: Chinese imports which cannot be serviced if something goes wrong; or good ones that are kinda' expensive. The whole K40 was only 400 bucks delivered...

    I'm starting to get the feeling that this thing is kinda like an inkjet printer... yeah, the main unit is cheap; where they get 'cha is on the accessories and consumables... oh well, in for a penny, in for a pound, I guess...





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    Default Re: How much heat do CO2 lasers generate?

    Can't remember how much I paid in all honesty, was like 4~5 years ago already. Think it was that, close to $300 but certainly not more. Are you trying to say the frontdesk clerk punched it all wrong?!
    You've checked with your local aquarium fishy-supplies like I did? Who knows maybe they'll hook you up a cracking deal. Might be a bit more today maybe, dunno.

    Depends really, for hobby maybe better with the cold-side tap water bucket and pump kit? (rinse/refill hourly type thing).



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How much heat do CO2 lasers generate?

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How much heat do CO2 lasers generate?