Looking for a new laser tube for your K40 laser machine? Check out Cloudray Laser!

Cooling your laser tube is one of the most important things you have to do 110% on your machine. The most expensive part in your machine is the laser tube and a new one will set you back 100-150 USD plus a month of waiting if you can´t find one locally or pay premium shipping.

With this article i want to go trough the watercooling, how to use it, what you need and how the optimal water cooling setup should look like.

A short notice, this article is not a how you must do it, just a article about how to do it properly to save money, time and keep the machine and parts alive for longer time. Less risk of anything happening. There is other takes on the cooling situation i will not go into just because the risk is high and i cant tell you to do it without feeling i mislead you.
So, with that said. Just because it isnt in my guide isn´t the same thing as you should not do it – just be careful and know the risks.

The coolant

Choosing the proper coolant for your tank is a article by itself, you can read it here.

The coolant tank

There is a easy way to explain this.
Your laser tube will create heat, the coolant carries the heat away from the tube into the coolant tank.
How big of a tank you need depends on the cooling.
If you have a active cooler, let´s say a CW5000 or similar, a compressor cooler you will get along nice with the built in tank of 3-5 litres for sure.

If you not have any cooling at all, the increase of the temperature in the tank will be quicker if you have a 5L tank than a 50L tank. The thermal properties of water can be used here to prolong the time you can use the machine before the water needs to be cooled down.

For peltier or radiator cooling types, the smaller amount of water you can have is better. The water will heat up quick but also cool down quick. If your cooling capacity is lower than the heating you want to have more volume in the tank.

To prevent growth in the tank it´s important to keep the tank out of sun light, and keep a lid on it.
Read more in the coolant type article how to keep the water fresh – here.

Flow, pressure and heat dissipation

Pressure is dangerous in our setups as the tube is very brittle and do not want high pressures, another effect may be that you blow off the hoses from their fittings with too much pressure.
Often the included pump is enough but if you want to grab another one there is some numbers you should check out.
Lift height: This is the pressure in some means, you want the pump to be able to lift the water out of the tank and into the machine. When buying a new pump, make sure the lift height is at least 5-10meters.
Flow: Either described in litres per hour (L/H) or litres per minute (L/M), use a free conversion tool from google if you have other standards of measuring the water to convert it 😉

My suggestion of a pump
12V based pump (you need a PSU for this, 2-5A)
Flow rate of: 10-20L/min.
Lift height: Minimum 5 meters
TE485 E 10 main1

Cooling types and solutions

There is three types of cooling solutions for your water, or four if you count the ambient air, but i call that ”no cooling” 🙂

No cooling – your tank is not cooled at all, just by the ambient air.
Peltier cooling – the tank is cooled passively or active by a set of peltier elements.
Compressor cooling – cooled by a refrigerator system
Air cooling – pulling the water trough a radiator or heat exchanger

Before i dive into the different cooling types, a well used solution to cool the water is to add frozen jugs of water into the tank, cooling down the water. This is a option but i do not use it myself due to the risk of cold spots. The temperature in the tank will differ and this is not good for the tube.
If you use frozen ice to the tank, make sure the water is properly mixed before using. This will be different for almost everyone so you have to check it.

No cooling
For this i would suggest as big coolant tank you can get. 25L+ as the ambient air around the tank is used to dissipate the heat from the water to the air. It will take longer for the water to come down to proper temps again.
Running the machine with temps greater than 25c can and will hurt the laser tube with time.

Peltier cooling – the tank is cooled passively or active by a set of peltier elements.
This cooling solutions is for the DIY nerds, its pretty advanced and you need to do a lot of tinkering and tweaking to get it right.
The efficiency of the peltiers are very low, on a 300w input you might get out 20-30watts of cooling, topps.
If you have cheap electricity and like to do DIY stuff, go for a peltier setup. You can make one to cool a 40w laser for about 50-60 USD.

Compressor cooling
cw5000 water chiller 110 volt cw 5000 chiller industrial water cooling system for co2 laser machine.jpg 640x640
This is the perfect cooling solution for all types of lasers. It´s also the most expensive one as the coolers will set you back 4-800 USD depending on the model.
You can, if you have knowledge how to make your of from a old refrigerator.
Just a note, whatever you do, do not buy a CW3000 cooler – they are not a cooler but just a small radiator with a fan, wasted money!

Air cooling
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Cooling down the water trough radiators is a pretty good option. It will double the time you can use the machine (depending on ambient temp) compared to no cooling at all.
Combine the radiator loop with some ice blocks in the tank and you have a pretty good setup.
If you live in a colder climate like i do, i have a long hose from a extra pump in my tank going outside the window to a radiator mounted outside the house at fall/spring/winter cooling down the water, free cooling and it works awesome.

Antifreeze and cold ambient temperatures


I often hear ”i use antifreeze and it works”.
The person mentioning this is not lying, it works for him. But the statement is at fault.
Compare this to
”I use spices on my meat and it always turns out good”
Now you think, what spices, what amount? If i pull out fish spices on my steak, will it be perfect?
This statement is made as antifreeze is the same all over the world, and every brand is the same.
They are not, at all.
Some antifreeze has metal additives to help the heat pickup into the coolant and this can destroy your tube. Others has a mix that will increase your water conductivity by the thousands, while some made for RV, truck or machine use may be perfectly good.
If you want to go the route by using antifreeze, ask the user who told you what brand he uses, amount in the mix and the ambient cold temp he has to get a similar setup yourself.

I do not suggest antifreeze at all, not even RV-antifreeze just because the risks. I do not want anyone coming back to me, reading what i said and blame me for destroying something for them.

So, how can you use your machine in a cold area in the winter?
You shouldn´t, thats the boring answer.
Electronics, water and the machine itself won´t like it at all.
But, if you want to do it – heat is the best solution.
There is aquarium heaters to buy cheap, use them into the cooling tank and wire heaters or regular light bulbs inside the machine a hour before use to heat the electronics a bit.
This will put less stress on the electronics, and keep the water flowing.
Some kind of alarm or watchdog on the heaters is a good idea, they often has a built in thermostat.

Security and warnings

Knowing the water is flowing is a good thing to know, there is numerous reports of people forgetting to turn on the water before firing, me included and this will destroy the tube within minutes, or even seconds.

Flow indicator
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A simple spinning impeller can be found at PC cooling stores, use this to see the water is flowing trough the tube fore running the machine

Flow sensor
A flow sensor is a electrical sensor you install on the inlet hose to the tube. When the impeller turns the two cables have a open loop, its a NO circuit.
Connect this sensor to P+ and GND, or WP and GND depending on which power supply your machine have. If the water stops flowing the laser cannot fire.

Arduino security warning system
This is a bit more complicated, you need to be experience Arduino user to get this to work.
But its a beautiful setup who can monitor temperatures, flow and other details you want information about on your machine and trough relays it can stop any firing if there is a problem.
I will do a own article about this further on, how you can build your own and all code needed for it.

You can install a relay to kick the water pump at the same time you turn on the machine.
Buy a 240v relay, use the live main wire inside the power button to kick the relay and connect to the water pump. Use a 12v relay if you have a 12v pump and use the 5V to trigger the relay.

Have a suggestion on something i forgot, how is your cooling setup made – comment below!

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F4VSJ, Hans

I preview to add an electrical simple beer cooler (around euros) as chiller. Contains up to 5 liters of cooled water and the (beer)-cooling systel I use for the water of the laser tube.
As fast as it is installed I will send some pictures and my experience with it


Do you have recommendations on replacement tubing for the water cooling system? The silicone tubing that came with it is too flimsy and kinks easily. I’ve bought some more silicone tubing but it’s just as bad. The inner diameter seems to be about 8mm.


Here’s my thought, you have tank of water and pump.

On the return to the tank, the water is running through a coil of copper tubing in a bucket full of ice water.

That water is cooled by the ice water then returned to bucket.

A bypass valve would allow the amount of cooling to be controlled.

Any thoughts?


in response to a peltier controller, I’ve made myself one. The board is a PIC based one and it can control 4 peltiers (even more, since it only drives gates of FET’s), monitors flow and right now two temperatures. Panic button, SSR based on/off, manual or automatic operation. 4×20 LCD or OLED display to give you info about temperatures and flow. FET’s are not implemented on board because of the high currents involved. It prevents K40 to start if the temperature of the water is too high or if it doesn’t flow. It shuts it down K40 if the water temperature is too high, panic button was pressed or the water stops flowing.It is mostly made with through hole elements because i don’t like soldering SMD’s. Right now I’m tinkering with the optimal setup of timings and temperatures and also with the setup of cooling tanks on coolers.

Daniel Bottner

I added a 1/6 HP Submersible Utility Pump -1600 GPH – 8 meter lift – to increase water flow from 1/4 liter a minute to 3 liters per minute. I had to create an adapter to reduce water outlet size. Epoxied together a 3/4″ PVC elbow, with a PVC reducer & a brass hose fitting. This centrifugal water pump is said to produce 15 lbs. of pressure. Make sure you secure each hose connection at least on the water inlet side of the system. I have read elsewhere that 1 liter per minute should be sufficient.

Chris Hansford

Im just setting my unit up for the first time …can I make a cheap suggestion…you can buy computer temperature monitors for around £10 on ebay.
The normally fit into a 5.25 Bay and have a very nice digital colour dusplay giving everything from HD temp to processor temp to fan speeds …even a clock on most of them.
The last one ive just bout has 3 type K thermocouples on long wires….use these for your cooling radiator…water temp (make sure there completely waterproof first….thin heat shrink with a sealed end works well for me
You can fit 12vdc fans to the radiator x2 normally and best of all these little unit not only cheap but tun on 12vdc from the computer supply …so rewire to a computer style power supply and they look great and work a treat.
Tip…the 12vdc power supply for your water pump…if that’s what your using also being 12vdc so wire the temp unit to the pump circuit.
As for power…the laptop style power supplies come with a kettle lead and normally have a plug fitted….cut the plug off fit an in line fuse for added safety (3amp max) the connect the earth to the chassis earth point where the supply comes into the back of the cabinet and run the brown and blue (230vsc live and neutral) up to the main cabinets on off switch.
Connect accordingly to the switch side of the switch and use a few small tywraps to hold the cable neatly in place.
Every time you turn the power on the pump will start up automatically and the nice colour display shows you the temp of water….fans etc.
Because these type of power supply’s give out at least 2 to 3 amps if not more uou can also fit an led stick on internal cabinet light …I recommend fitting an inline switch to this light and again you can drill the main control panel and fit a nice push button with latch to allow you to turn the light on and off.

Caution note…mKe sure all connection to the main control switch are insulated after wiring complete and please remover power to the entire machine before you start.
If your not sure ask someone yo help that does….
Have fun.

R and S

I can’t seem to get my laser to cut much of anything before it overheats. Takes hours to cut 5mm wood.

Last edited 3 years ago by R and S
Michael Pyman

I run the power for the water and exhaust fan from a short extension lead. Laser water and fan all switch from one socket so all on at same time, the laser not powered up until I turn it on from control panel.

Wagner F.

Whats with the IKEA mini refrigerator Tillreda ? Its a compressor fridge.
In Austrian we have up to 35 centigrade in summer and up to -10 centigrade in winter.
May be this fridge should do the job at warmer periods, or not?!

Eduardo Barriga

Hello, I am using ordinary distilled water and it is cooling fine. I live in Bogotá, Colombia at an elevation of 2.650 meters above sea level. Our climate here is average 20 degrees C. Is the system I am using enough and safe? I am using a tank with 8 liters capacity, is this enough? Thanks a lot


I got a peltier chilicube from chilipad, I know this sounds made up but goto ebay and get one. The overall product is a water cooled mattress pad they work great FYI. On ebay you can usually get just a cube for say $100 or less. It simply works perfect for this application. An all in one solution for cooling a K40, keeps mine at about 17-18c. PERFECT and it looks nice.

Terry Perraut

how to you connect hoses to the chilicube? using the drain plugs? Something else?


what about running your water through a coil of hose in a Magnasonic Portable 6 Can Mini Fridge Cooler & Warmer (cheap), start fridge and pump awhile before using to cool whole tank of water, to get the right temp i figure if it not cooling enough just a longer hose coiled, hose is cheap and a few feet would be a minimum amount,,i have been thinking of getting one, drill 2 holes, in and out, run hose through coiled inside then to my 25ltr container , still keeping the water container should keep larger amount of water cooled ? start with 3-5 feet of hose coiled inside and if needed add a longer hose for more cooling..less hose for less if to cool ? anyone try anything like this ???


sorry, forgot to mention, it says on the mini fridge it keeps inside 35 degrees below ambient temp, other reason to still use 25ltr container, so not to cool, sweating in laser tube shouldnt happen then ? thoughts anyone..


thx for input, it is not a compressor, but thought if I still kept 25ltr tank and cooled it before firing laser., and big enough coil of hose inside mini fridge it might work, but I don’t want to waste my time either on anything..thx


Great article, thank you! I’ve got a question about the CW-3000. I live in a cold part of the world (northern Scotland) where ambient temp is about 15°c for the summer and 5°c in the winter. I don’t think I’ll need active refrigerated cooling and should be able to get away with fan assisted radiators. With that in mind, is the CW-3000 a useful ideal for a simple closed system? I can get one for about £80, which isn’t that bad. Is this unit better or worse than doing a DIY computer cooler approach? I’d like to keep it simple and I’m wondering if the CW-3000 might be a way to do it in my context? Thank you!


Many thanks for replying so quickly. Really appreciate your time and help.


Hi Håkan!

I live in a tropical country where the dew point hovers around 25-28 degrees celcius (ambient air temp is around 28 to 32 ish) and hence I get some wicked condensation on my tube with the ice block method! (inlet/outlet temperature at approx 12/14 degrees)

I was wondering, if it might make more sense to run it say at 20-25 degrees but with a higher flowrate? What do you think?

Appreciate your ideas on this!

Thank you!


Ah! like to clear the condensation by evaporating / blowing it off yes. Got it will give it a try!