Cooling the laser's tube.
Prior to purchasing and operating the K40 I received most of my laser experience with a Universal 30 Watt system that I had access to. I did not know how lucky I was, and how hassle free Universal's products are. The Universals have what I believe are metal laser tubes which are air cooled, or at least some sort of tube that does not require a chiller to cool.
It was an interesting discovery when investigating the K40, that the tube needed to be cooled with a water supply, and one reason I hesitated to purchase one.
Here is a shot of the tube. You can see the intake and outtake tubing at the bottom of the picture. If you look careful you can also see where it attached to the glass laser tube at the upper left side of the image.
The pump for the cooling system is simply an aquarium/pond pump. Here it is in a bucket of water that I am currently using. Some of the "quaint' nuances of the K40 system are the crazy cheap workarounds. The pump/cooling system is a classic. It does, however, work really well. I don't think I'll worry about upgrading it for some time.
One of the reasons I sprang for a K40 was that the current model had a water flow shut off function. that is, it the temp gets too high (I hope), or no water is flowing, the system shuts off, sparing the tube from quick failure.