Arduino-controlled secondary coil cooling?

Melting ice is about the most efficient cooling mechanism we mere mortals can use to cool lasers. Ice is also good for “transporting cold” from much bigger machines that have big, efficient refrigerating compressors, these same machines being ones you probably already have - refrigerators. You can actually store cooling in frozen water bottles.

The trick is getting some control of the process. Most K40s already have a bucket of water for cooling. Put in a second bucket, fill it with ice and water, and selectively circulate the main K40 water through a copper pipe in the ice water bucket. Use something like an Arduino to measure temps and control how much of the K40 coolant gets pumped through the ice reservoir. Water running through a spiral copper tube in a water bath is a very efficient cooler. The Ice reservoir could profitably be a cylindrical drinking cooler - cheap, insulated, and easy to plumb.

I think this approach could handle holding the K40 water at optimum temperature constantly. One nice thing about an ice water reservoir is that the water temperature is constant at 0⁰C as long as there is any ice at all. A second bucket, a second pump, and some electronics gives very good control over coolant temperature. And it can be automatic, functioning quietly until it runs out of ice and temperature rises. Then it can honk at you to feed it more ice.

Waterproof DS18B20 one-wire temperature sensors are cheap and easy to use with arduino. One in the cooling reservoir and one in the ice bucket, super easy. Also, lots of people upgrade 3D printers with newer control boards, and most of what they throw away are basically arduino with lots of extras. Add a flyback diode and use the heated bed MOSFET to control a DC pump in the circuit. You can probably hook up the one-wire sensor to almost any port such as those running the limit switches. The board probably already has a buzzer that can sound and maybe even an LCD.

Monitoring and alarming are simple on Arduino, I think there’s even reference example code in the IDE. I know that when my son and I did our experiments sonicating homemade ice cream, we didn’t even bother looking for examples, because it was so easy to code up monitoring and alarming with one of those waterproof DS18B20 sensors. He did most of the coding, though I showed him a few tricks. :slight_smile:

(This comes to mind because I’m planning to rebuild my original 3D printer replacing lots of parts, including the control board and display. I’m going to use mine for a different non-3d-printer purpose, but the concept remains.)

You don’t really need to build anything to monitor your water and tube temperatures. There are available modular temp controllers with sensors, setpoints, alarms and relays for controls.

Definitely don’t need to. :stuck_out_tongue:

I’m with Michael on this one. Sure, we don’t need to build anything. But as for me I >>GET<< to design custom control logic, circuits, controllers, and control panels. I love this. Been doing something similar all my life. I feel like I’m living in a Golden Age where I can get a highly capable general purpose controller, with video, keyboard and mouse interfaces as well as general purpose I/O for under $10 (Raspberry Pi Zero W). Arduino and PIC solutions are even cheaper.

Buying a $10 Pi >LETS< me add on as many temperature sensors (and DS18B20 is a favorite) as I like, do calculations, store readings with time stamps, and send those by wifi or bluetooth to another machine as needed, as well as being able to send in cut files remotely… WHACK!!!
Thanks, Cartwright. I needed that. :laughing:
I love making controllers and score how well I did by how functional and cheap they are to complete. So yeah, bring on the temp sensors.

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Once, when my wife was away, I was curious about the temperatures in our kitchen fridge. So I put 3 DS18B20s in the fridge section, and 3 in the freezer section, and started logging data every 15 seconds.

When my wife came home, she was kind of unhappy.

You see, I had put the sensors only in the top, middle, and bottom of the front of the fridge, and she wasn’t convinced that only three sensors in the fridge was adequate to characterize the fridge performance.

Then, one morning, while I was on the treadmill, she said, “Could you check the fridge logs? I think it died.” Sure enough, I could see the last cooling cycle had happened at 10PM or so the night before, and that it had been warming since then.

The replacement fridge has three DS18B20s in the front, three in the back, and three in the freezer. (Starts to sound like jokes about fitting elephants in a volkswagon.)

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In the pharmaceutical analytical testing industry you have big environmental chambers where drug products are put in stability storage at different temps and %RHs. The metrology departments have big carts with a data recording system and like 30 or more thermocouples for doing zone mapping and calibration. Sounds like your rig would fit right in :slight_smile:

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