View Full Version : Unplug laser unit cooling fans for cold garage?

Mike vonBuelow
12-01-2011, 7:54 PM
Anyone know if the laser will perform better if I'm in a non-heated garage, and I unplug the cooling fans?

Or maybe all but 1? Max temp in the garage is 'maybe' 60F, probably more like an avg of 50F during these upcoming winter months...

Is there a way to monitor the laser unit's temp?

Just wondering about options as last year I just totally shut down for the winter. :(

Mike Lassiter
12-01-2011, 8:46 PM
my understanding with our laser is there is a fairly small temperature range recommended for storage or use. Too cold affects the seals which could cause gas leakage, too high and pressure builds up and not good for seals. We keep our building in 65 -70 degree range. Purchased laser mid 2008 and so far still going strong. I hope I didn't jinx it.

Joe Pelonio
12-01-2011, 10:04 PM
I agree, read the manual. It should show the operating temperature range, and more likely you should use a heater to warm up the garage.

Frank Corker
12-02-2011, 6:10 AM
I'm afraid I would never risk knocking off the cooling fans, you have no idea how fast and how hot it would get, I think it would be a mistake and could prove incredibly expensive for you.

Rich Harman
12-02-2011, 6:47 AM
This may be obvious but remember that air blowing across something will not cool it down further than the ambient temperature. The cooling effect only happens when there is evaporation taking place.

Dan Hintz
12-02-2011, 7:54 AM
To add to Rich's comment... a heat source (i.e., laser cartridge) will not be as effectively cooled by simply sitting in cold air as it would if a fan were blowing air across the cooling fins. Even in a cold environment, you could overheat the cartridge without proper airflow.

Mike vonBuelow
12-02-2011, 1:49 PM
To bad the unit does not have the technology to modulate fans as required by temperature... like CPU fans.

Glen Monaghan
12-02-2011, 4:43 PM
This may be obvious but remember that air blowing across something will not cool it down further than the ambient temperature. The cooling effect only happens when there is evaporation taking place.

Umm, depends on what you mean by "the cooling effect." The term "convection" refers to a cooling effect which has nothing to do with evaporation. Moving air cools an object faster/more effectively than still air does. You probably know this effect by the common name "wind chill". (Same thing works in reverse, ie moving hot air heats faster/more effectively than still hot air, hence convection ovens that allow you to cook quicker and with less risk of burning than possible in conventional ovens without raising oven temperature).

Rich Harman
12-02-2011, 6:13 PM
What I meant by "cooling effect" is cooling below ambient temperature. You can move the air as fast as you want over an object and it will not reduce it's temperature below the temperature of the air, assuming that no evaporation (or pressure drop) is taking place.

Moving air will certainly cool something faster, just not below the temperature of the air itself.

In the case of the fans cooling the laser in a 50 degree garage, you can leave all the fans on and the laser will not cool below 50 degrees.

Glen Monaghan
12-03-2011, 1:00 PM
The issue is not that you won't cool the laser to below ambient room temperature; the issue is that you may overheat the laser even if the room temperature is relatively low when the fans aren't running to move air over the fins.

Heat moves from warmer to cooler, so the ambient air temperature MUST be below the laser tube's fin temperature for there to be any cooling of the tube by ambient air alone, regardless of whether the air is stagnant or moving. While moving air won't cool the tube below the temperature of the air itself, moving air DOES cool _as though_ it is cooler than the air actually is because the rate of heat transfer is proportional to the temperature difference. As still air absorbs heat from the fins, it warms up, reducing the temperature difference and so lowering the heat transfer rate and cooling less effectively. Warm air rises, so normally there would be some turnover and some cooling would continue. However, if the air can't circulate easily through the box by natural convection, it will eventually warm to nearly the tube temperature and provide essentially no cooling at all, EVEN IF the room air is quite cool.

No laser engraver I've seen was designed for natural convection alone; they all rely on a fairly significant volume of forced moving air (and/or water, but the OP's machine is air cooled) to cool the tube, power supply, motors, and circuitry.

Moving air continually absorbs heat at the maximum rate allowed by the temperature difference between ambient and the fins because, as soon as the air contacting the fins absorbs some heat and starts to warm up (lowering the temperature differential and reducing the heat transfer rate), it's replaced with fresh ambient temperature air. Again, that's why we have "wind chill" readings and why convection ovens work. For example, when the air is 50 degrees F and moving 5 mph, it cools as though it were 48. But, the big thing is to have moving air because stagnant air, even if it starts out at 50, will soon rise to near the tube's temperature. As the air temp approaches the tube temp, the lower heat transfer rate will allow the tube temp to rise higher and, without adequate convection to waft the heat away, the stagnant air and tube can eventually reach a temperature where the laser fails.

(On the other end of the temperature scale, 100 degree F air blowing 1 mph will heat you as though it were something like 105. Cranking your oven above 350 in an attempt to bake your cake faster is more likely to simply burn it, but if you can blow the air over 350 degree heater coils and around your cake at 3 feet per second, you cake will bake as though you set the oven to about 380, except without the burning risk.)

Sorry that I got wordy, and I promise to keep out of this topic from now on... Bottom line is: Cooling below ambient temperature is a red herring. The point of a fan system is making the air cool more effectively than ambient temperature would do by itself. Our laser machines are designed to have a significant air flow to remove damaging thermal energy. As Dan noted, "Even in a cold environment, you could overheat the cartridge without proper airflow."

Mike Lassiter
12-03-2011, 4:29 PM
it seems to me the condern should be the laser being in too cold an enviorment for it's well being. tht was how I interputated the condern. I was taking unhooking or disconnecting the fan being done to avoid blowing the cold air over the laser cartridge.

Now the direction the thread seems to be going; while interesting seems to be missing the point of concern.

Mike vonBuelow
12-03-2011, 8:19 PM
^^ got it ;)

I need the laser to be warmer in my freezer office

Rodne Gold
12-03-2011, 9:26 PM
The laser will generally perform better colder , and if its a RF tubed model , should have a thermal cut off anyway , IE the tube will shut down if it's getting too hot before damaging itself. Of more concern at low low ambient temps is condensation if the air isnt dry.

David Fairfield
12-03-2011, 10:01 PM
I'm afraid I would never risk knocking off the cooling fans, you have no idea how fast and how hot it would get, I think it would be a mistake and could prove incredibly expensive for you.

Ditto that!

AL Ursich
12-03-2011, 10:57 PM
The mention of the LASER in a Cold Enviroment.... I think Condensation Moisture will be the big factor.... Moisture on the metal parts including the Mirrors and Lens..... Then there is the High Voltage Arcing Factor with the Tube..... SO I would be sure you have warmed the Laser to the point that the cold parts have evaporated the moisture. And be aware that Kerosene Heaters produce Moisture to some extent... In my Navy Years I saw many cold weather related Radar Condensation Problems..... Mostly with High Voltage Arc.

IF it was my Laser..... I would build a wooden frame like a box and mount it to the overhead with rope and pulleys and cover it with clear plastic.... Insert 1 or 2 100 Watt Bulbs in a Protective housing and Ceramic Socket. The Bulbs would act as Heaters keeping the chill off of the unit. All the Police and Fire Remote Transmitters in our area have light bulbs running 24/7 just to keep the moisture problems in check...

OR build a Room within a Room..... And Insulate and Heat it.....


Mike vonBuelow
12-04-2011, 12:11 PM
Making a small frame to encompass just around the laser unit was an idea... and an enclosed continous lightbulb might be the solution. That would keep it "warm enough" & not to cause damage. I can do all the computer work inside, and then only have to be out in the garage for the actual lasering time.

Mike Lassiter
12-04-2011, 2:11 PM
Mike from what I got from material we got with our laser; I think you risk greaty reducing the usable life expectancy of your laser cartridge by allowing it to be in that cold an enviroment.
We have our laser in a 32x12 building. I do not vent the air externally due to cost and no way to heat or cool this size building when you are using 1500 cfm blower. I haven't got the filter arrangement to my satisfaction yet, but the laser is maintained in a temperature range ULS stated in the owners manual. The air changes per minute using the size exhaust blower we have makes it unpractical to condition the air for it to only be sucked out of the building. Also consider the air you vent out has to be replenised by air coming back in the room. This can be a expensive lesson to learn.