Cooling like a Pro...

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Preben Hovedskou
Posts: 104
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Location: Haarby, Denmark

Cooling like a Pro...

Postby Preben Hovedskou » Thu Sep 01, 2016 12:51 pm

Hi freinds of lasers..

Do I need a chiller for my machine.?


Some of us live in hot areas, and for sure need a real chiller. Others live in colder climate and have to fight against the water freezing.
But a lot of us live right in the middle (like Russ)..: A few months the temperature is high, and a few month it can go a few degrees below zero (Celcius).
We dont really need a real (expensive) chiller but can normaly run with a simple jar with 20-40 liters of water. In the beginning I made one of a plastic box with a lid, containing about 30 liters. But I had some problems in the summertime with this design. I also had air-bubbles in the tube every time I started the machine.
If we just put a little bit of design into this simple jar, we can optimize the cooling quite a bit, and maybe save us from buying a real chiller.


1) Separate the water.!
I have seen a lot of pictures in here, where the hose for returning water is placed right in front of the pump.
The hot water is sucked directly into the pump again, and dont get time to cool down and mix with the whole tank capacity.
If you divide your tank into more sections, you force the water to flow a bigger distance and mix slowly into the colder water.
Make some dividers in your tank to form a "labyrinth" for the flow.

2) Deep is better than flat.
Heat will seek upwards, so a pound with water will always be coldest at the bottom.
Therefore we can bennefit a little bit of making our tanks deeper.
I also found out that the pump start very hard, and is actually capable to suck down a little wortex of air from the surface, if the tank is too low.
After making a deeper tank I never have air in the tube anymore.

I made my new tank in a old camping coolbox. NOT because I think it can keep my water cool, but I just had one on my store and the shape and size was perfect.
So why not..? It will for sure not make the water hotter.!
And as an ekstra bonus it have wheels and handles and the colors perfectly match the machine.. ;-)
Preben
50W KH5030 TL (blue/white)
RDworks 8.01.19 Win10
Qcad (qcad.org)
15 years experience as service-technician for industrial lasers.
( http://www.bystronic.com )

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Preben Hovedskou
Posts: 104
Joined: Wed Jul 13, 2016 6:49 am
Location: Haarby, Denmark

Re: Cooling like a Pro...

Postby Preben Hovedskou » Thu Sep 01, 2016 12:55 pm

1) The cooler was nicely fittet with two separators.

2) I made some new ones in 5mm acrylic, one with holes in the top and one with a port at the bottom.
Mounted the separators in the tank and sealed them with silicone.

3) Then I mounted the return-hose near the surface in the right compartment, and the pump in the left compartment.
I drilled holes in the lid for two pieses of 12mm plastic pipes, and connected the hoses. I also mounted a sensor for a cheap temperature-controller to monitor the water temperature and control the cooler. (and later I will also add a heater)

4) On the outside of the lid I mounted a pair of push-in fittings for the hoses. Then I can easily disconnect the hoses if necessary.

collage01.jpg


The hot water comming back from the laser now goes to the surface in right chamber. It now have to go all the way to the buttom before it can flow to the next chamber. Here it again have to go to the surface, before it can flow to the pump-chamber. Once again it have to go to the buttom before it reaches the pump.
During 20 min cutting at full power, I measured the temperatures between the "hot" and the "cold" chamber, and I read a difference between 2 and 3 deg(C). (whithout the cooler running!)
When I make a pause in the production, the temperature fall very quickly again. This never happened with my old tank, it just got hotter and hotter.
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Preben
50W KH5030 TL (blue/white)
RDworks 8.01.19 Win10
Qcad (qcad.org)
15 years experience as service-technician for industrial lasers.
( http://www.bystronic.com )

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Preben Hovedskou
Posts: 104
Joined: Wed Jul 13, 2016 6:49 am
Location: Haarby, Denmark

Re: Cooling like a Pro...

Postby Preben Hovedskou » Thu Sep 01, 2016 12:57 pm

5) Mounted a very cheap temp-controller to monitor the water-temperature at the return hose. (ca.12$)

6) The controller have two relais, one for cooling and one for heating. I hooked up the power for the camping-cooler over the controller.
Later this year I will mount a heating-element for aquarium in the tank, and hook it up via the controller too. In this way I can avoid freezing.

7) After heavy production I have 20 deg. at the return and 18.5 deg. at the pump. (the two thermometers are calibrated together)

8) My new tank fit nicely into the design of the machine.. ;-)



collage02.jpg


Keep cool out there... ;-)

-Preben-
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Preben
50W KH5030 TL (blue/white)
RDworks 8.01.19 Win10
Qcad (qcad.org)
15 years experience as service-technician for industrial lasers.
( http://www.bystronic.com )

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Jay Wrightson
Posts: 63
Joined: Thu Jul 14, 2016 6:21 am
Location: UK, Belfast

Re: Cooling like a Pro...

Postby Jay Wrightson » Sat Oct 15, 2016 3:18 am

Why does this work though? I understand the concept and the logic well enough - but where does the heat go?

You are collecting all the warm water returning from the laser in one compartment, keeping it away from the pump and making it hard for the warm water to get near the pump. But why and how is it cooling. Is it essentially being neutralised by the larger cooler body of water in the other two compartments?
-Jay

-------------------------------------------
50W Blue and White Chinese Laser, 500 x 300, TL
RdWorks V8.01.18
N Ireland, UK

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Preben Hovedskou
Posts: 104
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Location: Haarby, Denmark

Re: Cooling like a Pro...

Postby Preben Hovedskou » Sat Oct 15, 2016 4:54 am

The heat can only escape via the surface. The cooling-box sucks in fresh air and blow it via a cooling-unit over the surface and out of the box again. So you always have a chilled airflow over the surface. The idea by separating the water and force it through a "labyrinth" before it goes to the pump again, will give the water more time to chill and make full usage of the tank capacity. I've seen many fotos in here where the return-hose is placed right in front of the pump, whitch will just recycle the hot water and make it hotter and hotter.

-Pepsi-
Preben
50W KH5030 TL (blue/white)
RDworks 8.01.19 Win10
Qcad (qcad.org)
15 years experience as service-technician for industrial lasers.
( http://www.bystronic.com )

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Jay Wrightson
Posts: 63
Joined: Thu Jul 14, 2016 6:21 am
Location: UK, Belfast

Re: Cooling like a Pro...

Postby Jay Wrightson » Sat Oct 15, 2016 8:21 am

Ah ok, so the cooling box you used has some sort of powered cooling ability. That makes much more sense indeed :D
-Jay

-------------------------------------------
50W Blue and White Chinese Laser, 500 x 300, TL
RdWorks V8.01.18
N Ireland, UK

User avatar
Preben Hovedskou
Posts: 104
Joined: Wed Jul 13, 2016 6:49 am
Location: Haarby, Denmark

Re: Cooling like a Pro...

Postby Preben Hovedskou » Sat Oct 15, 2016 11:47 am

Yes but it's absolutely not capable to cool down the water..!
It just blow a small chilled wind over the surface, so the heat can escape the box.
The issue here is the seperation of the water.! This system take the whole volume of the tank into action, and give you a much better effect than just using a big jar. The same teknique is used in some industrial lasers. (but here we are also talking 300 liters of water and a very effective chiller!)
Before I made the separation the water just got hotter and hotter. Now I have a quite constant temperature, and the compartment with the pump is 2-3 degrees(C) colder than the "return-chamber". For people living in my area (Denmark) it can be exactly what we need to avoid the need for a expensive chiller. Now the winter is comming closer, and I need to deal with the opposite problem. To avoid the water freezingovernight I now also mounted a aquarium heating element to the tank. This element use only 25W, have a built-in thermostat and will keep the water at ca 20 degrees(C). I can also control it over my temperature-controller witch have a relay for heating also. So If the water goes under 10 degrees(C) I start the aquarium heater, that will stop heating arround 20 degrees(C). If the water goes higher than 20 degrees(C) the chiller in the box will start.
Simple and cheap system that works very well for me. (but maybe not for people living in other climates?)


http://www.ebay.co.uk/itm/Trixie-Aquari ... cQwl2PUdFg


-Pepsi-
Preben
50W KH5030 TL (blue/white)
RDworks 8.01.19 Win10
Qcad (qcad.org)
15 years experience as service-technician for industrial lasers.
( http://www.bystronic.com )

Kevin Rodden
Posts: 75
Joined: Sun Oct 02, 2016 2:32 pm
Location: Leigh, Lancashire. UK

Re: Cooling like a Pro...

Postby Kevin Rodden » Sat Oct 22, 2016 1:32 pm

What a great idea, found the thread to be very informative thank you.
Can i ask what is the ideal water temperature for a laser tube?

Cheers
Kev
60W 700x500 TR
Kev

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Jay Wrightson
Posts: 63
Joined: Thu Jul 14, 2016 6:21 am
Location: UK, Belfast

Re: Cooling like a Pro...

Postby Jay Wrightson » Sun Oct 23, 2016 2:11 am

Kev, I spent some time looking into the ideal temperature myself and there does seem to be a range of opinions. The safest most generally agreed consensus I could find was to keep the water temperatures between 16C and 18C but people were reporting using their laser with temps of up to 25C+ long term with no problems.
I like the 16C to 18C theory personally, it's disconcerting when you dip a finger into your water reservoir at 17C and it feels warm to touch. Hard to imagine how it can be taking heat away from the tube when it gets too much warmer.
-Jay

-------------------------------------------
50W Blue and White Chinese Laser, 500 x 300, TL
RdWorks V8.01.18
N Ireland, UK

Kevin Rodden
Posts: 75
Joined: Sun Oct 02, 2016 2:32 pm
Location: Leigh, Lancashire. UK

Re: Cooling like a Pro...

Postby Kevin Rodden » Sun Oct 23, 2016 9:27 am

Starman wrote:Kev, I spent some time looking into the ideal temperature myself and there does seem to be a range of opinions. The safest most generally agreed consensus I could find was to keep the water temperatures between 16C and 18C but people were reporting using their laser with temps of up to 25C+ long term with no problems.
I like the 16C to 18C theory personally, it's disconcerting when you dip a finger into your water reservoir at 17C and it feels warm to touch. Hard to imagine how it can be taking heat away from the tube when it gets too much warmer.


Thank you so much for the reply.
60W 700x500 TR
Kev


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