Water cooled spindles in winter temps

For those of you using a water-cooled spindle in an unheated space, I figured it would be worth sharing my solution.
To ciculate the water I’m using a knock-off CW-3000 ‘chiller’. The CW-3000 is not a true chiller as it will not cool lower than ambient temperature [I use a real CW-5200 for my laser as that is more temperature sensitive]. I use distilled water as the coolant as I wasn’t very comfortable using something like RV antifreeze. Some use auto antifreeze but over time that will cause corrosion (as well as being toxic).
In the summer that’s fine but what about when the temps start to get lower and the equipment is in an uninsulated/unheated space? I use a submersible aquarium heater - sunk into the coolant reservoir. To keep it at the correct level I made a replacement 3D-printed cap so that the heater is pushed down to the correct depth. You can find the files at Thingiverse as thing:4721066.

Note: A broken aquarium heater or pieces of plastic in the water tank is going to damage the pump and probably other components of your chiller and/or laser/spindle if a broken piece makes it into the circulating water. By using this item you assume full responsibility for any risk of potential or actual damage.

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That’s kind of funny. You need a chiller to cool the water and a heater to heat the water. Counterproductive, No.

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So you’re running the CW-3000 24x7 to keep the warm water circulating through the plumbing and spindle?

Hey David,

bullshit. Do you really think anyone would pour this into the cooling system of their car if it caused corrosion? It is precisely the similar conditions of the car cooling system and the spindle cooling system which is why car coolant is often used. It is if you don’t use the correct anti-corrosive and absolutely mineral-free (distilled = no electrical conductivity) liquid that you will harm your spindle.

(30 °C is 86 °F)

By the way, do you correctly warm up your spindle?

If you care that much of too cold coolant, how cold is ambient temperature in your workshop?


That was quite a wall of text there. I’m basing my coolant choice on this article from laser gods. Among other things, they say “automotive antifreeze is formulated to be safe with vehicle cooling system components but has been reported to degrade nylon and silicone, among other materials, that are common in laser cooling systems.”

Since my primary use is to cool a laser - lower conductivity and corrosion on laser cooling system components is my primary goal (along with keeping the cooling system from freezing in lower temps). It’s worked just fine for the last several years so I’m using it on the spindle also. I note that the coolant you are using is not auto antifreeze but one recommended for spindles - so I expect it has a formulation more intended for the purpose for which it’s used.

It’s cold enough this time of the year that the cooling cycle doesn’t kick in unless I’ve been running the equipment for a while. The aquarium heater keep the liquid from getting too cold and risking it freezing.

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Yes - I’d rather pay for the extra electricity than risk having the water freeze up. At some point, I’ll have a shop that can be kept warmer.

Hey David,

thank you for citing a source for your statement.

I retract my “bullshit” because in it I learn that there is at least something else I didn’t know existed: Car antifreeze that has such high electrical conductivity, i.e. not actually made with distilled water. I wouldn’t put that in a car either, because minerals precipitate.

But you contradict yourself by referring to this source, but then not following the recommendations it contains. You say you use distilled water, but according to both my advice, and your source, you should use more than distilled water. It was because you wrote that, that I had the impression that I should write something.

As for the spindle coolant liquid I use and have linked to above, with the ethylene glycol it contains, it should hardly be possible for my spindle coolant to freeze. I have also explained the function of the other ingredients above, e.g. with regard to corrosion inhibition, the non-aggression of seals made of rubber, a high (alkaline) pH value, and the lowest possible electrical conductivity.

I would say that the fluid I use is very similar to what your source recommends in terms of the ingredients mentioned and explained.

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Hey David,

What do you mean with “doesn’t kick in”? Do you mean it does not flow?

If you use no ethylene glycol, but only distilled water, couldn’t it simply be that your water froze? Adding ethylene glycol would prevent freezing. As I wrote above, it is spread in tons every year over airplanes to deice their wings. And it is an ingredient of car motor anti-freeze and of my super-expensive spindle coolant as well.

OT: Your profile photo is nice. Did you make it? Is it a goshawk? It reminds me when this year I saw an Eurasian sparrowhawk in the tree in front of my sleeping room. Tried to make a photo but difficult to focus with it sitting between the branches.

The water is flowing. What I meant is that the water doesn’t get hot enough while the spindle is running for the chiller cooling cycle to start. I have not run multi-hour carves like I see some do so the spindle isn’t running for an extended time and heating up.