DIY 5289 Btu/h chiller

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Jack Balauro
Posts: 5
Joined: Thu Jun 18, 2020 3:10 am
Location: LA County, CA
Country: USA
Nickname: midiman310
Laser Machine Make or Type: Orion Motor Tech
Laser Power: 50W
Laser Bed Size: 300mm X 500mm
Home Position: TL
RDWorks Version: 8.01.18
Ruida Controller: Other
Accessories: 5000 BTU Chiller, Various Focal Length Lenses
Windows Version: Windows 7 Home

DIY 5289 Btu/h chiller

Post by Jack Balauro »

Was doing some very heavy cutting a few weeks back and glanced over to see my "fish pump" water reservoir heading towards 40 degrees C. As the temperature was rising, I noticed my power was not cutting the material as effectively as at the beginning of my laser work. This while the tube still drawing 22ma. I was told that I should keep the tube between 20 - 25 degrees C. during laser tube operation for optimal results.

Decided to kluge together a laser chiller from a used 5000 Btu window AC unit in the local classifieds. The unit selected was within a year old, made for a small room and is dimensionally small as possible while maintaining the minimum 5000Btu/h cooling rate.

Bought the AC unit, stripped it apart, removed the evaporator fan and ran the unit. I wanted to see how cold the evaporator would get sitting there. When the compressor kicked in, frost formed on the evaporator within 45 seconds. So decided to get to work on my chiller initially as a "proof of concept" build.
Evaporator.jpg
Built a box out of 1/4" plywood, fiberglassed the inside and built acrylic divider to isolate the evaporator in the lower half. The return line would have to flow through the evaporator coils before returning to the fish pump to pump the now cooled water back to the tube. Closed system.
Cooling Reservoir.jpg
First test was encouraging as I could easily drive the water reservoir down to 5 degrees C from 26 degrees C ambient start within 6 minutes.

Here's the system in action during a cooling cycle.
Cooling.jpeg
I'm still experimenting with the best placement for the thermal sensor, condenser cycling, calibrations, etc. The AC unit had a mechanical "cooling" thermostat unit that I replaced with a W3230 digital thermostat unit. These are cheap and can be had everywhere on eBay. I happened to have one that I had used previously on my plating tanks.

Here's the final schematics and diagrams of my build.
Chiller Electrical.jpg
Chiller Refrigeration.jpg
What I like about doing this is if it came down to a large or high power tube in the future, I could always scale up to a large AC unit.
Chiller 1.jpg
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Jack Balauro
Posts: 5
Joined: Thu Jun 18, 2020 3:10 am
Location: LA County, CA
Country: USA
Nickname: midiman310
Laser Machine Make or Type: Orion Motor Tech
Laser Power: 50W
Laser Bed Size: 300mm X 500mm
Home Position: TL
RDWorks Version: 8.01.18
Ruida Controller: Other
Accessories: 5000 BTU Chiller, Various Focal Length Lenses
Windows Version: Windows 7 Home

Re: DIY 5289 Btu/h chiller

Post by Jack Balauro »

A year later and this chiller is the best thing I've done for my Laser Tube. Today was very warm (35C ambient temp). Did a bunch of cuts (the max was 12+ minutes long and the water going into the tube was a rock solid 18.9C! The tube was definitely happy and best of all consistent during the entire cut and scans. During the course of the year, I've never have had to run in the high fan mode as the fan in low cool does well to remove the heat from the coils. Air blowing through the radiator is definitely a lot warmer than the ambient air. No ice needed here. :D
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