CW5200 Chiller setting recommendations for warm environment

Community Laser Talk
1

Hello all
I have a 10 month old Monport 80W laser and live in Phoenix where it gets really hot in the summer. I have an attached finished garage with a wall AC. I have a problem, with this laser and the last one of light banding engraving. I believe I asked here and consulted with a tech what the heck this was and how do I fix. I never got an answer that worked. But when I was talking with a Trotec rep he quickly said that it was a problem chilling the laser tube.

And sure enough— this winter my shop has gotten a little nippy and I got great engraving. I have been watching the chiller and it seems that at 19 it’s great. The temperatures creeped up this past week into the high 70s -low 80s and chiller got up to 21 & 22 and back came the bad engraving.

I viewed a couple You Tube videos but most of it was how to set it up. I have never touched the settings since installing. And one video warned not to mess with the settings too much because you don’t want condensation on the tube. We are pretty dry here. I think humidity hovers around 30% so I don’t think I need to worry about that OR do I?
How do I achieve the chiller never going above 19? This weekend I put on the AC and that helped but won’t when the temperatures get higher soon.

Thank you very much for any advise!!

2

I lived in Peoria for almost 2 years with my OMTech. I have a 5202 chiller. I have it set for 20C (68F).

It seems fine until it’s it’s too hot in my garage for me to take, at about 105F. Chiller seems to keep the tube at 20C.

I do feel it works better when cooler. I am now in the Verde Valley and it still gets over 100F in the summer, but it doesn’t seem to be a problem.

I’d love to know how that happens…

I think your 30% is pretty wet, most of the time we are in or near single digits unless in monsoon. I’ve run mine with thunderstorms around and never have seen any condensation on the tube…

:smiley_cat:

3

Quality has its price… :+1:

Now you don’t specify units of measurement, but I assume we are talking about Celsius degrees.
If your tube has a constant temperature in the band from 16°C to 30°C it should be able to produce uniformly, that is what most manufacturers recommend in their manuals.
The lower temperature limit is determined by the dew point and can be different, all depending on where you are in the world and how high the humidity is.
The upper limit is a little more fluid and not quite as visible as the lower one. I have a laser friend in Australia, he drives with a large container filled with ice and tries to keep his 80Watt laser cold… He has a few problems, but nothing related to engraving or cutting quality. (I highly recommend running a CW5000/2 or similar!) One of his problems is that he has to constantly monitor the temperature and constantly refill ice in an even amount or the temperature runs wild or the tube condenses…
It is the violent and very rapid temperature change that kills a tube - in my opinion.
However, IF you keep the temperature constant at, let’s say 26°C, then there is no quality difference in your engravings. I’m not saying that you get the same output from your tube at 16°C or 30°C, but I am saying that if the temperature is constant you get the same result.

4

My comment goes directly to the chiller, ignoring the consequences when it comes to engraving.

Taking advantage of being a chiller technician, there are tips to be followed so that the chiller works properly.

  • The chiller must operate in a place that is as cool as possible.
  • It must be installed in such a way as to avoid air recirculation.
  • Filters must be kept clean.
  • Leave space between the chiller and nearby objects so as not to obstruct air free circulation.

In the specific case of this chiller I found this video:

Apparently it is possible to choose between two types of operation:
D1 - Absolute temperature control (independent of ambient temperature)
D2 - Differential temperature control. (from what I understood from the video, this was the mode chosen)
The difference between these modes translates into:
D1 - To obtain the temperature entered in the setpoint parameter regardless of the ambient temperature.
Example: If you want a water temperature of 19º, you set the value of 19 in the setpoint and the chiller will keep the water at that value “19” + the differential which is the interval value in degrees that the chiller will control the water (this value as to be inserted in it’s parameter too). If the setpoint parameter is 19 and the differential parameter is 2, the chiller turns on at 21 and turns off at 19. Traditionally it is like this but not always. It can turn off 18, turn on 20 and 19 and the average value of the differential value. You will have to see how it works to define how it works correctly.

D2 -To keep the water temperature slightly above or below room temperature to avoid condensation.
In this case, the value to be inserted is just the differential, because the setpoint is the room temperature.
Example: 1 - Ambient temperature 30º, “setpoint” value which is actually the differential 2. The chiller turns on at 32 and turns off at 30.
2 - Ambient temperature 20º, “setpoint” value which is actually the differential 2. The chiller turns on at 22º and turns off at 20.
3 - Ambient temperature 30º, “setpoint” value which is actually the differential -2. The chiller turns on at 30 and turns off at 28.
3 - Ambient temperature 20º, “setpoint” value which is actually the differential -2. The chiller turns on at 18 and turns off at 20.

5

I live on the Gulf Coast of Florida and we typically have higher humidity / dew point. I ran my chiller at a constant 18C, in D1 mode, but found that to be below the dew point some days and would get condensation. My tube died (out of TEM00 mode) after less than 300 hours of use. I don’t know if the condensation was the cause of, or contributed to the failure.

After replacing the tube I switched to D2 mode with a 3C setpoint. I have not had any condensation issues since then. I do run AC in the shop in the summer unless I’m only going to be there a few minutes which helps reduce the interior humidity.

The key takeaway is that you want the chiller temperature above the dew point in the room where your machine is located to avoid condensation on the tube. A simple thermometer with a humididty reading and an online calculator will give the dew point at your machine.

The OP stated their humidity is very low where they are at. I do not think running in constant temp. mode would cause a problem for them, but know what the dew point is.

6

Starting from the principle that I know little about CO2 lasers,… If I had one and I was faced with moisture forming in the tube, due to professional influences, what would come to mind would be to insulate the tube. I know there is high voltage in the tubes and I believe at both ends.
Anyway, why can’t the tube be insulated since the tube temperature is controlled by the fluid? :thinking:

7

There is no obstacle to insulating a CO2 tube, as long as you can check that there are no air bubbles in the tube, I would say.

8

Is there enough condensation to cause it to pool condensed water within your machine?

I haven’t had a long time with these, about 5 years but I’ve fixed lots of different kinds of equipment. To be good at trouble shooting you have to develop how you troubleshoot.

Understanding how they work, makes it relatively simple to fix most things or at least zero in on something rather quickly. In other words, I like to know why I’m doing something.

I have read many threads about tube condensation, even from the commercial laser manufacturers, nobody has any reason to state that it will harm the tube itself.

What happens in a glass tube laser is inside, and as long as you’re not causing issues with anode high voltage or so much condensation that it’s dripping into the electronics, what kind of a problem is it?

None of the manufacturers that speak about tube condensation, that I have read, says nothing about harm to the tube. It’s really about water getting into the other parts of the machine.

I can’t see how it would effect what goes on inside the tube itself. I had a tube fail at about the same hours as yours, also a TEM00 failure. This adds to my doubt it anything to do with the condensation.

@DougL has a K40 for over seven years. He drives it like a diode in the on/off mode with a set mA. I think the mA is too high, but he states the tube still works and is over 7 years old. I have no reason to doubt him.

I think it boils down to how the tibe was manufactured. These have to have their mirrors set by computers and it’s very precise. I think something isn’t quite perfect when they make them and they don’t last as long… IMHO.

Some parts must be exposed, such as the output.

Most people who own these are not what I’d call unintelligent, and if tube insulation would work, I’m sure you’d have seen it by now.

I still question if you need to worry about condensation at all in most locations.

Thanks for chiming in, in any account :tada:

:smiley_cat:

9

I was more concerned about the possibility of High Voltage arcing to the chassis, than actual damage of the tube internally. I don’t know that the condensation contributed at all to the failure I had.

I do know that high voltage and water don’t play well together. Spraying water around spark plug wires was one of the methods we would use to locate bad wires.

I absolutely agree. Most of my career was as an Auto Mechanic and if you don’t understand the technology you’re working with, you will struggle to repair it.

10

CO2 lasers straight up lose 1% efficiency for every deg C above 25C. A 5% loss from a 5C rise could be accounted for by slowing the job by 5% from the start, but now you’re overcutting a little and have to track the temp when you calibrate and waste your laser’s potential by tuning for the worst case.

But raster banding is going to be obvious with even a small % of variation, and there’s nothing you can do about that. If you wanted to get super technical, you could build a tube power supply that started holding some power back and increased the current with rise in temp to keep it constant, but of course that would be far more expensive and power-limiting than just getting the right chiller.

If your chiller isn’t maintaining temp, most likely it is low on refrigerant. This is common. They will run a bit louder too, but they’re loud anyhow so it may be hard to notice a gradual change.

I have not seen a chiller with a recharging port, but you can add one, and fill by watching low side pressure alone. You won’t have a high side port to gauge from, unfortunately, but you can still do it. And once you have the port installed you can maintain it.

If it’s an R134a refrigerant, you can just buy the auto parts store and it’s cheap $10 for each 1lb can. But many newer chillers use R410a, which legally you need an air conditioning tech license to get R410a. I think you might be able to do an online test and pay some fees to get the cert, but TBH Facebook marketplace is full of people who you can get it from. But R410a comes in 20lb cylinders that sell for $250 today. That’s what you will pay. But it’s useful for refills in the future too.

Or it could just be an undersized chiller. Get a bigger chiller. If it’s a “fake” chiller (just a heat exchanger, a fan blowing air through a water-filled radiator and no refrigerant system), toss it and get a real one.

There are hard limits on wet-bulb temp of the room you run it, because you can’t allow it be so cold it picks up condensation. It’s usually not about feeling “muggy”- warm air holds MUCH more water than cold air, so it’s more about high temp than high relative humidity.

11

Kind of a blanket statement.

Where I live it can get to 105F or higher in the summer. It gets higher, but I’ve found, I’m not enjoying myself over about 105F.

105F at 5% relative humidity, the dew point is about 20F, so it’s not going to happen here. At 10% relative humidity is about 37F. Being in the single digits, relative humidity wise, during summer is why they call it a dry heat. There needs to be enough water available for the air to absorb it…

I believe I did mention that it didn’t interfere with the anode voltage (high voltage). It shorting to ground would qualify as interfering with the HV.

I think the dielectric constant of condensation is pretty low.

In any case, I agree, keep you paws away from the anode voltage.

:smiley_cat:

12

An 80w laser is quite powerful and that also means heat generation so cooling temperature management is critical since you don’t want to operate at or over 25C. I too would expect engraving variances at 19C vs 22C and if you need consistency then it sounds like you need a better water temp management system. I don’t know the spec’s of the CW5200 but if it has a +/-3 degC spec you have the wrong chiller.
The only way I can see condensation changing the power output is by condensation getting on the laser output glass at the end of the tube. As @jkwilborn mentioned, the working portion of the tube is inside another but and the water jacket is isolated from the outer glass with an air gap. Condensation of contaminated air at the electrical insulation joints could be problematic if those joints are no longer sealed but otherwise that too should make no difference in performance. But you might want to make sure your LPS is seeing any of this condensation and see that it’s getting cooled and not over heating. Testing could be done using a liquid CPU cooling rig attached to your LPS such that it can regulate and stabilize the LPS temp.

Another option might be a larger distilled water reservoir between your CW5200 and your laser tube or even making that insulated reservoir a closed loop with the GW5200 and a 2nd loop covers your laser tube including insulating your water lines.

my K40 is a hacked machine and is as @jkwilborn mentioned ~7years old. I never run it over 24C and my cooling system is a 5 gal bucket of distilled water with 2 aquarium pumps. There’s a closed loop cycling water through a drinking water bubbler chiller having ~10 loops of copper tubing in the 5gal reservoir to cool the reservoir with all lines insulated. The 2nd circulation pump cycles through a circulation indicator/water temp indicator through the laser tube and back to the reservoir dropping into the middle of the copper tubing loops. So my tube input water is what I monitor and these are cheap little aquarium pumps so not really fast moving water but seem fast enough.
I originally cut 3mm plywood at 12mm/s at 55% power and currently 12mm/s at 65% power. My default power setting used to be 2.4V on LPS-IN and currently it’s 2.6V on LPS-IN so there is tube wear happening.
My water is distilled with one small drop of Dawn dish soap and a couple of drops of fish tank anti-algae formula.

13

Is that something you can document?
But anyway, why make it more complicated than it is? What I’m saying is that if your temperature is constant, it can’t have a varying influence on the output quality of a laser machine. And if you really lose 10% laser power at a water temperature of 30 degrees Celsius (which I definitely don’t think is real), and you engrave fine lines, it doesn’t matter at all.
The starting point is of course always a well-functioning laser machine and a stable and even cooling of your CO2 tube, the actual temperature range of your cooling machine, should be up to your own experience and needs.

14

I used an 8000 BTU air conditioner to build my “overkill” chiller. I have the cold side submerged in a 25 liter vat of antifreeze. Then also submerged in the cold tank is a radiator for a secondary loop of distilled water to the tube… It is very efficient and keeps the tube at whatever temp I want… I set the cutoff to the chiller side to 13c. I see temps fluctuate at the tube under high load up to 15-18c max.

15

Correct. But google tells me 30% RH is kinda the upper end of what people call a “dry heat”, and that’s a 67F dew point. RH is the portion of how much moisture air can hold at that temp. 105F air can hold a LOT of moisture. 30% of that max is still a lot of moisture so being in a really hot shop doesn’t necessarily mean your dew point is going to be really low. It could be surprisingly high

16

Thank you for all the replies. It’s quite overwhelming and way over my head of understanding. I thought it would be a quick adjustment. I bought a thermometer with humidity read out. Tonight it’s cold outside - my garage /shop is 69 degrees/22% humidity and the chiller is steady at 19 and engraving is great. Maybe the trick is when the outside temp starts to increase I have to have the AC on and keep the shop at 69 degrees. But that’s very chilly for me – I hate very cold AC and a freezy cat. Is that the simplest way or is it going to be very hard to maintain that when outside is 100 degrees and above?

17

My chiller works up to about 105F, having been there many times. I think you should listen to @Dannym in that it’s likely low on refrigerant.

Unfortunately, these machines have no way to check the refrigerant. They have left out the places to tap and check - another way to lower cost.

Add to that, I couldn’t find a refrigeration place that I could bring my chiller - all had their businesses setup to be mobile. This means a call out to the house, of course more money.

You chiller should work at 70 without an issue, mine hangs in there at above 105F. Might try and see if you can find someplace to have it checked. I had problems finding someone Phoenix area of Arizona.

:smiley_cat:

18

Some quick tips:
A chiller with a low freon (gas) charge has symptoms such as low performance and the air that comes out is cool. Putting the chiller to work with a high liquid temperature allows this doubt to be clarified.

Chillers (small in size) are sealed because the filler port is considered a potential leak point. With current environmental legislation (which differs in different parts of the world), this solution has been chosen to avoid equipment being serviced by non-specialized personnel.
Now, at least here in Europe, only certified and specialized personnel can work on equipment with a high greenhouse effect. Legally of corse.

If you bring the chiller to my workplace (Portugal to find you) I’ll check if everything is ok (or not) and I’ll even buy you a beer! :innocent: :grin:

19

I’m sure there is little that the Chinese do to enforce the environmental laws of other countries. May be required for international sales. It does fit into their MO, less parts and more difficulty to service for the user.

I wish our legislators would control where our data, not by repetitively banning of platforms in an attempt to control the misuse of USA data … The EU has much better protections for it’s people than the USA.

Next time I’m in the area I’ll drop in, and yes I’d love to have a beer…

I’ll leave the chiller at home :rofl:

:smiley_cat:

1 Like
20

Would love if I was in Portugal.

Thanks again. I think I’ll just buy a new one. It’s not a huge expense compared to the trouble of fixing it. It did go through a fire last March I didn’t think it suffered because the fire was small and contained in the laser. But there was a lot of soot and smoke in the shop. Maybe it compromised it even though I have cleaned the filters many times.

So if I get a new one that will resolve this even though I’m in such high heat in the summer?
I know I have to keep the AC on at around 74-75 degrees but it’s better than 68