Water cooling (for equipment that requires it), cheap but effective solutions?

[pipe2null]

This topic is about water cooling for equipment that absolutely requires it, such as CO2 laser tubes, water cooled CNC spindles, HPA air compressors, etc.  It is NOT about computers or CPU cooling, although if there are good multipurpose solutions from computer-land that meet the "cheap but effective" criteria to use with other equipment types, I suppose that would make the cut.

I'm in the early stages of a couple DIY CNC build type projects, one is a CO2 laser cutter and the other is a very, very humble CNC mill for basic aluminum milling.  ATM I'm trying to decide on, surprise surprise, which water cooling solution to go with.  The laser requires it, but I also intend on a water cooled CNC spindle since at least in theory it should run quieter than an air cooled spindle and work better at lower RPMs.  I've read (don't remember where) that to maximize the life span of a CO2 laser tube you should run it at less than 20 deg C, and if your ambient temperature is not low enough, you have to use a compressor based water chiller.  So, I'm trying to work out a better-than-a-bucket DIY solution.

For DIY as well as commercially produced CO2 lasers, I've seen the CW-3000 ($150-$500) and CW-5000 ($500-$1200) chinese water chillers suggested, and AFAIK are about the cheapest commercial product as you can get for what they do, so they make for a good baseline of comparison.  The 3000 is just a glorified reservoir and radiator with external equipment shutoff output (important), and the 5000 also includes a compressor for better heat dissipation.  Either one supports only a single water cooling loop.

For radiator-only solutions, I've looked at various PC related products and I have the impression that the CW-3000 is still the cheapest in comparison and is already specifically built for lasers and such.


The current idea I'm exploring is: Why not build a water reservoir into a small compressor-type refrigerator?
Example products ($220-$260):
https://www.amazon.com/Bottles-Wine-Cooler-Freestanding-Double-layered/dp/B08B1MWHYC/ref=pd_rhf_dp_p_img_8?_encoding=UTF8&psc=1&refRID=4MR94GB5NHMZ0N4DF52Z
https://www.amazon.com/Beverage-Cooler-Refrigerator-settings-Perfect/dp/B08BL6Z92B/ref=pd_rhf_dp_p_img_7?_encoding=UTF8&psc=1&refRID=HP8EMT3XX8QP8J3TF87C

Main advantages I see (and could be wrong about):
- Active cooling with compressor
- Cheaper than CW-5000, assuming pump, water flow and temperature sensors are not too much additional
- Much larger reservoir capacity
- As many water cooling loops as you want (individual laser, CNC spindle, etc. loops), at cost of one pump per loop.
- Can still add a small external radiator to the return side of water loops if water temp rises above ambient, like for multi-kilowatt CNC spindles
- Water reservoir is always pre-cooled before equipment is even powered on, so maximum cooling capacity for "short-ish" CNC jobs

Main disadvantages:
- DIY is often PIA
- Very unlikely cheap fridge will maintain temperature lower than ambient for longer CNC jobs
- I am a little bit concerned about water vapor condensing on laser tube due to lower temperature chilling, since CO2 lasers use substantially high voltage.......
- Other problems that have not occurred to me?!?


Thoughts?  Other angles of attack I should consider?

[Gregg]

For the super quick and easy water cooling how about a bucket of water with ice in it and an inexpensive water pump.  If you need to keep pure or treated water separate, immerse a coil of copper tube in the bucket of ice water. 

A small refrigerator with a tank of water inside probably doesn’t transfer heat as well as if the evaporator coils of the compressor system were in direct contact with the water being cooled.

A cheap DIY compressor chiller could be made from a dehumidifier, even a used one.  Try the local thrift stores or craigslist.  I have one that I would give you if you are local and can pick it up.

There are lots of sites that tell you how to build a cheap water cooler for welding torches that simply are a reservoir, radiator and pump.  Automotive transmission coolers are cheap radiators for a DIY passive cooler.

[duak]

I've got a bit of experience with both cooling laser systems and CNC spindles of 10 or more HP.

One place I worked at produced a number of diode laser assemblies that dissipated up to a few hundred watts.  Many of the labs or test areas just hooked up to a large recirculating system.  Other labs just had little chillers, smaller than the smallest fridges.  The systems used Dowtherm SR-1 coolant to prevent corrosion as brass and aluminum were in contact with it.

You can indeed have problems with condensation if the assembly is cooled below the dew point.  The building we worked in had fairly low humidity but you had to be careful not to over cool whatever you were working on or it would dew up.

I have a couple of old hoses and fittings.  They're quite neat in that they are like quick connect pneumatic fittings except that both sides are self sealing so they don't leak when detached.

It's the spindle bearings and oil that may have extra cooling.  The spindle motor is usually air cooled,  CNC spindles generally need cooling only when turning high RPM (> 8K) or when machining harder stuff.  Aluminum is generally not a problem.  However, if the spindle manufacturere calls for a chiller...

I have a dehumidifier at home that has a humidty level control.  If I turn it too far it runs continuously and the evaporator (cold) coll will ice over.  As Gregg says, this might be a better starting point than a fridge.  Just figure out a way to put the evap coil in the coolant reservoir and you're off to the races.

A final thing, the flow rate isn't that high, so could town water be an option?  Just watch out for corrosion and mineral buildup.

[pipe2null]

Thanks for the feedback!

@Gregg:  I hadn't considered the dehumidifier route.  I would probably take you up on your offer, but I'm in the Pacific Northwest, so unlikely that we're neighbors.  I appreciate the thought though.

A significant part of my current CNC projects is basically "Apartment Friendly CNC".  Aside from the laser requiring it, I'm getting into water cooling a bit more than necessary in the theory that it will minimize noise pollution, or at least centralize the noisy parts of cooling to one spot where I can attempt sound dampening.  "Apartment Friendly" laser should be pretty straight forward, just need to pay extra attention to filtering the exhaust air (and fire suppression).  But a CNC mill is going to be a pretty big challenge, probably will require a beefy enclosure more similar to building insulted interior house walls than building a box...    But if I have to do water cooling for the laser anyway and using a water cooled spindle might reduce noise a bit, then it seems like a good route to go.  For example, I picked up a somewhat quiet California Air Tools air compressor for my lab and built an UGLY makeshift enclosure for it with cardboard, duct tape, and spray-on expanding foam.  Just that bit alone reduced noise by about 10 dB.  If you happen to know of any spindles known to be really quiet (when not ripping through material), please suggest.  But I digress.

I previously decided that if I can't fea$ibly do active cooling, it will probably be best to go with the cheap chinese industrial CW-3000 radiator just to keep things simple since it has built in alarms for shutting down equipment if cooling fails.  Ice buckets are always a good go-to in lieu of nothing else, but I have nowhere to put equipment that is not carpeted (apartment) so I just know my clumsy self will accidentally dump 5 gallons out on the carpet sooner or later.     Town water...  Hmm...  Well, I get free water with the apartment, so it is a potentially really cheap option, just put in an inline water filter, pretty inexpensive.  I'll have to think on that one, tying into the existing apartment plumbing might be a bit tricky as far as running hoses between rooms...

I'm thinking the "ideal" solution for my apartment is a central active cooling unit (that I can sound dampen as needed) that I can use for however many cooling loops I need, within reason.  If I can do a decent DIY for cheaper than the single loop chinese CW-5000 active compressor cooler, then that's probably the direction I'll go.  I have a month or two before I'll need working water cooling, so I have some time to look around.  Seems like finding a used/cheap compressor-type dehumidifier to tear apart is probably a good next step.

Thanks!

[Ian.M]

It may be worth looking at an ex-office water cooler.  It already has everything needed to chill a small tank of water, just remove the tap and plumb it to a circulation pump and put the return back in the top.   Chiller capacity will be dependent on the compressor fitted, and you can probably boost it a bit by adding a fan to its air-side heat exchanger.

Whatever you chill with, you are going to need to either circulate ultra-pure deionised water (and its a PITA to keep it pure enough), antifreeze, strong brine or use a biocide to  prevent biofilm buildup which can drastically reduce heat transfer.   In a closed loop system, plain tap water, (or even distilled water in a system that isn't totally sealed and sterile), is asking for trouble and in addition to impaired cooling and possible blockages due to biofilm buildup, will end up smelling like a swamp monster with a personal hygiene problem unless you flush and refill very frequently.

[coppercone2]

if you use water from the tap put a remote switch to turn it off because you might get scared to turn off a leaking on fire machine.

Like a light switch by the door to exit the room so you can turn it off when you leave to get a fire extinguisher.

[NiHaoMike]

Town water...  Hmm...  Well, I get free water with the apartment, so it is a potentially really cheap option, just put in an inline water filter, pretty inexpensive.  I'll have to think on that one, tying into the existing apartment plumbing might be a bit tricky as far as running hoses between rooms...

Get some PEX tubing and some adapters to connect it to the faucet.

if you use water from the tap put a remote switch to turn it off because you might get scared to turn off a leaking on fire machine.

If there's a fire, it usually makes more sense to keep the water running. I don't think very many hobbyists are going to be machining magnesium or other materials that can continue burning with water poured over them.

[sokoloff]

For a spindle at/under 3HP (what seems like a fairly high though sensible limit for an "apartment mill"), I'd spend the money to buy a high-quality spindle and not farf around trying to water cool it. You're going to get way more noise from the tooling and stepper motors.

Here's a 3HP, 12K RPM spindle (with brand new bearings, so slightly noiser than after it's been run in):
https://www.youtube.com/watch?v=hKPV4puTPk0&feature=youtu.be&t=29m07s

Concentrate on the laser; use air purge (or nothing) for the mill spindle, IMO.

[RenThraysk]

Aquarium water chiller/cooler?

Remembered a video from Linus, so possibly a terrible idea.

[coppercone2]

Town water...  Hmm...  Well, I get free water with the apartment, so it is a potentially really cheap option, just put in an inline water filter, pretty inexpensive.  I'll have to think on that one, tying into the existing apartment plumbing might be a bit tricky as far as running hoses between rooms...

Get some PEX tubing and some adapters to connect it to the faucet.

if you use water from the tap put a remote switch to turn it off because you might get scared to turn off a leaking on fire machine.

If there's a fire, it usually makes more sense to keep the water running. I don't think very many hobbyists are going to be machining magnesium or other materials that can continue burning with water poured over them.

you don't want to fight a electric fire with water!

[Gregg]

@pipe2null:  I am not close to your location for the dehumidifier.  I was thinking that a dehumidifier is ¾ of the way to making a refrigerated water cooler. 

But back to reality; you could make a really cheap water to water heat exchanger with a length of garden hose with a copper tube snaked through it and make up some standard Y fittings to seal the copper tube at the ends.  Run your clean water through the copper tube making sure it can’t get airbound.  The good welding coolers use the same pumps that are used for making carbonated water they are relatively quiet and very dependable.

[pipe2null]

Aquarium water chiller/cooler?

Remembered a video from Linus, so possibly a terrible idea.

Hmm...  I saw aquarium chillers when I was window shopping for other parts.  I had assumed they would be too wimpy, but if it can keep up with the heat generated by an overclocked threadripper...  I'll add aquarium chillers to the list of options to dig into.

@pipe2null:  I am not close to your location for the dehumidifier.  I was thinking that a dehumidifier is ¾ of the way to making a refrigerated water cooler. 

But back to reality; you could make a really cheap water to water heat exchanger with a length of garden hose with a copper tube snaked through it and make up some standard Y fittings to seal the copper tube at the ends.  Run your clean water through the copper tube making sure it can’t get airbound.  The good welding coolers use the same pumps that are used for making carbonated water they are relatively quiet and very dependable.

Good tip on the pumps.  The rest of the purely DIY heat exchange is still on the table until I figure out how much (or very little) I can spend on water cooling, after motion platform and laser tube and hopefully decent spindle....  The part list for these machines are a bit longer than I had originally imagined, but if it was too simple, might get a bit boring.

It's the spindle bearings and oil that may have extra cooling.  The spindle motor is usually air cooled,  CNC spindles generally need cooling only when turning high RPM (> 8K) or when machining harder stuff.  Aluminum is generally not a problem.  However, if the spindle manufacturere calls for a chiller...

For a spindle at/under 3HP (what seems like a fairly high though sensible limit for an "apartment mill"), I'd spend the money to buy a high-quality spindle and not farf around trying to water cool it. You're going to get way more noise from the tooling and stepper motors.

Here's a 3HP, 12K RPM spindle (with brand new bearings, so slightly noiser than after it's been run in):
https://www.youtube.com/watch?v=hKPV4puTPk0&feature=youtu.be&t=29m07s

Concentrate on the laser; use air purge (or nothing) for the mill spindle, IMO.

I am still a bit of an infant when it comes to spindles, and still learning everything as I go.  When I did a quick check on "Amazon-grade" spindles to get a rough idea how much they cost, aside from the electrical power rating, they are usually advertised as "air-cooled" or "water-cooled".  I originally thought a "water-cooled" spindle might be a bit quieter, and after thinking about it, the whole thing will have to go into a sound dampening enclosure, and I expect it will get pretty hot in there so not sure how well air cooling will be for the spindle.  But it might be just fine, I don't know.  I am adding 240Vac wall outlets on the existing 20Amp circuits next to each of my electric baseboard heaters (Shhh!  Don't tell the landlord!) so I have that option. I welcome any and all (ideally good) advice on spindles, but assume I cannot afford an automatic tool changer.

Generally, the only materials I (currently) think I'll work with for milling purposes is PCB, wood, and aluminum, and laser cutting for anything else.  Aside from that, I have a one-time project I'd like to do making a few simple shapes out of actual stone (I'm spending my limited money on my CNC machine builds so, sorry fam, you're getting homemade gifts for Christmas this year, hehe), but AFAIK milling stone is just about the worst case scenario for milling, so not sure if I'll be able to achieve that one.  I'm not sure if stone is normally immersed in coolant or not, but I'm keeping that in mind as I look at different CNC build designs trying to figure out which direction I'm going for my own build.

if you use water from the tap put a remote switch to turn it off because you might get scared to turn off a leaking on fire machine.

If there's a fire, it usually makes more sense to keep the water running. I don't think very many hobbyists are going to be machining magnesium or other materials that can continue burning with water poured over them.

I was considering picking up a compressed CO2 tank and splicing it into the air assist line for the laser head.  If any flare up occurs that isn't blown out by the normal pressurized air assist, then key the valve for a burst of CO2.  I'm still debating on it, mostly since CO2 has it's own health hazards due to suffocation if there isn't enough ventilation.  But it's "apartment friendly" and good for the neighbors, in addition to the obligatory grown-up sized fire extinguisher.

FMI:  I was expecting the laser to be a fire hazard I need to deal with, but I have not heard of CNC mill/spindle use being a fire hazard.  Are there fire hazards with a mill I am not aware of?

[james_s]

If I were trying to DIY a water chiller I'd probably start with an old window air conditioner. They can be had cheaply at times, especially if you find one that's cosmetically dirty or beat up. They have the same sort of hermetic system as a dehumidifier but they're probably more common. For a super simple solution you could probably even get away with sticking something like a motorcycle radiator in front of the cold air vent on the AC unit, not the most efficient way to go about it but that MacGyver route is quick and easy.

[Rick Law]

Aquarium supplies is also a good place to look for small water pumps, filters, connecting tubing, so on.  The small ones tends to be the submerged ones, but they do have non-submerged ones and good mix of different capacities.  You can find in-line heaters, but I've not seen any in-line coolers.

I am not sure how well they will work with anti-freeze however.

[james_s]

Fountain pumps are readily available and the smaller ones are inexpensive. They're normally submersible but that should work well for this, just place it in the bottom of the reservoir.