Question re water system for Chinese CO2 laser

[Jacqui Marlin]

I just returned home after being gone for over a month and was going to fire up the laser when I noticed the water appeared cloudy. This is an HX3040 laser with a very simple system of distilled water in a container pumped through with an aquarium pump. It has worked well. When I checked the water I saw that ants had gotten into it (a problem here in Hawaii) and the water was not only cloudy but slimy and starting to turn green. I cleaned out everything completely including the pump but I would really like to set up a closed system to cool the tube.

My household water system is rainwater that has been double filtered and passed through an ultraviolet light. It is supposed to be cleaner than bottled water (but I am not sure about distilled water.) I bought distilled water for the system but would really like to hook this up to my household water, run it through some kind of cooling system and then through the laser tube.

If anyone has done something like this or has ideas I would love to hear them. I am not terribly knowledgeable about stuff like this but can follow directions. It is important that I can keep ants out as they have been able to get into closed containers in the past (they are very tiny!)

If someone else has used water other than distilled water without causing problems I would also like to hear from you as well. Thanks.

[Joe Pelonio]

Distilled water contains no minerals, which are harmful to the laser as scale forms on the insides of the passages.

Your water is fine for human consumption but the filtering you described will not remove the minerals.

What you are better off doing is to use the distilled water in a closed system, where a tank containing the pump is black so no light gets into it to allow algae to form. You can put some kind of gauge on it to top it off when needed
but have a tight lid to keep out ants and other contamination.

Bigger lasers use a chilling system where a different inert liquid goes through a refrigerated coil system.

[pete hagan]

Goddess

Welcome home...Certainly a closed loop system is what you want. To do this rather cheaply I don't know if I have a good answer but my chiller was worth the money. You MUST keep the tube cool and with the small fountain pump method it would be a little tougher but not impossible.

One possible method is to find two containers say an ice chest / picnic cooler to ice down the second smaller container that contains your pump and distilled water supply. When you are ready to start working dump ice in the cooler and run the pump for about 30 minutes to chill the water. It could be as simple as a gallon container holding the water / pump with appropriate access holes drilled for the tubing and power. This would be the poor man's method but you will be happy with the laser because keeping the tube cool is paramount to tube life. I think just running water and no chilling will result in a rapid increase in the water temp. After running my 60 watt for 25minutes straight at 100% power with the chiller the water temp will sometimes rise from 13C to 32C (55F - 90F). I try and keep the temp around 15C (60F)

[Joe Pelonio]

Pete,

What do you think about running a coil of plastic tubing into the freezer compartment of one of those small refrigerators? You'd have the added benefit of a place to keep your drinks cool. The refrigerant coils are all in the back so you could drill holes in the side and seal with silicone. Those fridges start under $100.

[Doug Griffith]

I'm not sure how "sealed" your closed loop system is going to be but I recommend integrating a blow-off valve to relieve pressure from the expansion of water as it heats up.

Also, depending on the ambient temperature, you could integrate something like an automotive heater core with a fan. They act just like small radiators.

Doug

[Mike Hood]

What you need is what we home brewers call a "jocky box".

You can can room temperature beer in one end and get ice cold beer out the other end. Of course cooling the laser with beer... wouldn't be as helpful as cooling the operator... I think you could adapt the logic: :D

http://www.micromatic.com/images/galleries/CB281R/CB281R-i-600x455.jpg

[pete hagan]

So my idea had some merit and even better I've been trying to talk my way into buying a ring roller for the shop and now I know why!

Pete :D

[Robert Murray]

You might find a great source of information on closed loop water cooling
looking at water cooled PCs.

www.overclockers.com is a good source I have been there for a number of years with some water cooler computer system I run. You will want distilled water as well as you will want to make sure all metal parts of the system out of the same metal. As this will stop galvanic action from causing problems in the system. Also to prevent problems you should mix in come antifreeze. This will prevent some of the problem with galvanic action as well as keep algae down. While there is some debate on antifreeze because it will make the system less effective then pure water it will help to reduce algae and other problem. The thermodynamics of water cooling system is more complex than you might think at first but with careful planing the system can be easy to maintain. I have closed looped water cooler computer running over 4 years with no problems. I only have to top off the water and flush the system once or twice a year.

You should take some time and read about closed looped colling system used in PC system as well there not the same they have and do face many of the same problem you will have in a closed loop system for your laser.

[Bob Keyes]

One quick word of caution! If you are going to use this type of non-thermostatic controlled cooler, be careful that the water doesn't freeze if you stop the pump. If you turn off the engraver the pump normally stops and freezing will occur in the coils. Then no water!!

[Mike Hood]

So my idea had some merit and even better I've been trying to talk my way into buying a ring roller for the shop and now I know why!

Pete :D


Pete;

I have a ring-roller here... but there's actually an even easier way to make coils like this using a wood closet rod dowel with a hole drilled through. I've built a few distillers in my garage (yep... stills) and rolling them tightly on a dowel works like a charm.

The jockey box works great because it can't freeze, and self buffers any heat changes (caused when generating varying heat). Remember... you're taking heat OUT of the water... not putting cold in.

[Bill Cunningham]

We used to use air cooled coils after the final stage of high pressure compressors.. Stainless tubing can be 'hand wrapped' around any round object.. We used to use a piece of 4" pipe for forming the smaller coils, and a standard oxygen welding cylinder for the larger ones.. Just wrap it around, while holding one end.. It won't hurt the tube, we used these coils as after coolers on 3000 to 6000 psi compressors, sometimes in a water bath before the water trap that enters the filter..No reason to think a larger diameter, even in copper, would not work as well cooling water!

[Jacqui Marlin]

Thanks for some interesting ideas for this problem. Right now I am using a dark container with lid and I use gel ice while I am working. So far the water seems to stay cool to lukewarm. I have only been experimenting though, and there are a few other problems to solve before I really get into more serious work. I want to improve the exhaust system which is vented to the outside, but isn't adequate if I work on acrylic. And I will be taking another trip in a couple of weeks - gotta see those grandkids before they get too grown up!

Meanwhile I have managed to get the laser head to start at the same place although I still don't quite know how to calculate the proper settings. It seems the head homes at the left rear of the compartment well back of the metal framework and the work bed. I have measured that distance to the place I want it to start and am playing with moving the head without the laser beam until I see where it will start. Once I get regular results that I can control I will write out what I learn for the Newly Draw program. If anyone else uses this software and has a better idea of how it works, please share as well. Little by little it is coming together - and I seem to forget what I learned when I don't use it for a month!

When I get back from my upcoming trip I will be concentrating on the cooling system and the exhaust. Now to figure how to hold paper down to cut bits for flower kits in miniature. A vacuum set up would work well but I am afraid it would defeat the exhaust. This toy sure can get complicated!