Plumbing a water-cooled spindle.

For my new 2.2kW water-cooled spindle I bought a pond pump and 10 metres of 5mm i/d PVC pipe from my local Home Hardware. A quick test gave a flow rate (with no head) of only 30 l/hour. Another test with only 250mm of the pipe gave 4 times that rate. This showed that it's the length of pipe that reduces the rate, not just the fact of choking the pump outlet to 5mm. A return trip to Home Hardware found that the 8mm size pipe will just accept the 5mm size inside it so I bought 10 metres of that. This size will also just fit into my new 70x15mm Banggood drag chains. A bit of PVC pipe glue plus some heat-shrink sleeving for good measure created a couple of stubs of 5mm pipe to connect to the spindle. The overall flow rate through the spindle is now 60l/hour.
Another advantage for anyone else who follows this plan is that the pump I bought came with a plastic outlet barb the right size for the 8mm pipe whereas I'd had to find a brass fitting and modify it in my lathe for the 5mm size.

Kit

PS What do you use to prevent corrosion and algal growth in your cooling water? I'm using distilled water and wanted to add some car anti-freeze (ha-ha, the lowest temperature ever recorded where I live is 7.6C) but was advised not to as we didn't know exactly what metals were in the spindle and it might have an adverse reaction.

Quote:

---

Originally Posted by Kitwn

For my new 2.2kW water-cooled spindle I bought a pond pump and 10 metres of 5mm i/d PVC pipe from my local Home Hardware. A quick test gave a flow rate (with no head) of only 30 l/hour. Another test with only 250mm of the pipe gave 4 times that rate. This showed that it's the length of pipe that reduces the rate, not just the fact of choking the pump outlet to 5mm. A return trip to Home Hardware found that the 8mm size pipe will just accept the 5mm size inside it so I bought 10 metres of that. This size will also just fit into my new 70x15mm Banggood drag chains. A bit of PVC pipe glue plus some heat-shrink sleeving for good measure created a couple of stubs of 5mm pipe to connect to the spindle. The overall flow rate through the spindle is now 60l/hour.
Another advantage for anyone else who follows this plan is that the pump I bought came with a plastic outlet barb the right size for the 8mm pipe whereas I'd had to find a brass fitting and modify it in my lathe for the 5mm size.

Kit

PS What do you use to prevent corrosion and algal growth in your cooling water? I'm using distilled water and wanted to add some car anti-freeze (ha-ha, the lowest temperature ever recorded where I live is 7.6C) but was advised not to as we didn't know exactly what metals were in the spindle and it might have an adverse reaction.

---

I used antifreeze. Didnt run my system for long but that will work.

Glycol based Antifreeze is normally loaded with corrosion inhibitors, so I would reckon it to be OK. I don't have that problem with my Kress :teapot:

Thanks cropwell,
I went water cooled partly because of the high ambient temperatures here (Exmouth, WA) and also the noise. My previous spindle was a Chinese clone of a Makita trimmer/router which screamed the place down as soon as it started and burnt out due to overheating. The new spindle makes as much noise as the pond pump before it starts cutting.

I was a bit surprised by what the salesmant at Auto-Pro said about anti-freeze but I know he's no idiot and thought a few other opinions would be worth getting.

Kit

Here matey. have a look at this - https://en.wikipedia.org/wiki/Antifreeze

Quote:

---

Originally Posted by cropwell

Here matey. have a look at this - https://en.wikipedia.org/wiki/Antifreeze

---

Reminds me of Time Team..."'ere Tony, come and 'ave a look at this!":excitement:

Now I'm even more confused, but it shows there's more to this than pouring in some green stuff.

Kit

Quote:

---

Originally Posted by Kitwn

Now I'm even more confused, but it shows there's more to this than pouring in some green stuff.

Kit

---

Good grief man, you can't use the green stuff, Gotta be blue or red G13 at least. Failing that, how about VW Beetle antifreeze :toot::toot:

Personally, I gave it up when they stopped the methanol based stuff.

Cheers !

Rob-T

Well it used to be green! That's only the fluorescein dye anyway. I Think the last time I actually bought anti-freeze in a shop Mrs Thatcher was still PM. I'd had enough of grovelling about under cars at the side of the road by then and vowed that as soon as I could afford it I was going to pay someone else to service my car. I would, of course, now purchase the latest safety approved product from a reputable Australian supplier.

Kit

Any good quality Ethylene Glycol based anti-freeze has corrosion inhibitors which will work well in a system which includes Iron, Steel, Aluminium, and/or Brass, use De-Ionised water too to avoid any chance of impurities building up inside the spindle.

I'm afraid Ethylene Glycol is out due the risk of poisoning the dogs if I get a leak and they lick it up. I'm tempted but my wife would never forgive me! The Proylene Glycol version is OK so I'm going to head for our local Auto-Pro and read the labels very carefully.

I obviously don't need the anti-freeze/anti-boiling properties of the stuff but some corosion inhibiters might be nice. I am also concerned about algae growing in the water. It doesn't get hot enough to kill the stuff but the ambient temperture here is perfect for it. If I don't find a suitable anti-freeze I might just go for adding a little chlorine based bleach (NOT the 'oxygen' stuff). A little further reading on Wikipedia sugests that a weak solution of 200ppm Sodium Hypochlorite will be strong enough for bug killing but won't attack the metals. Standard household bleach is about 5% (50,000ppm) so a couple of tablespoons of bleach in 10l of distilled water should do the trick.

Thanks for all the comments from everyone so far, this has prompted some interesting reading.

Kit

You should be aware that Sodium Hypochlorite is somewhat alkaline in solution and hence will attack aluminium a bit. Should be OK on plastics and stainless steel though. Alternatively once the bleach is dissolved you could add a little acid to compensate - you should then have an essentially neutral solution containing some chlorine - how soon this would diffuse out through the piping though I don't know.

If all you are looking at is corrosion inhibition, how about something like Fernox - used in central heating. I haven't researched it, this is just tossing an idea into the pot.

I used a pond pump too but found it rather noisy and with it being directly mains powered couldn't easily control it from my panel. I then went to a 24v self priming pump and that way I just control it via a normal toggle switch when required as the temperature reaches a certain temp.

When I get round to my build, I have acquired a second hand 24v pump, fan and radiator (120mm) and a perspex header tank, so I plan to mount it all directly on the machine. I have some NC 40degC thermal switches, so one of those will go on the spindle.

Quote:

---

Originally Posted by cropwell

When I get round to my build, I have acquired a second hand 24v pump, fan and radiator (120mm) and a perspex header tank, so I plan to mount it all directly on the machine. I have some NC 40degC thermal switches, so one of those will go on the spindle.

---

Something like

Attachment 25797

?

I'd keep it simple. The fan and pump are near silent (the rest state of the steppers is noisier).

I never cut for long - probably 30 mins max - but there're no thermal issues at 2.2kW.

Standard car coolant - that's been in there for a few years now.

Quote:

---

Originally Posted by cropwell

If all you are looking at is corrosion inhibition, how about something like Fernox - used in central heating. I haven't researched it, this is just tossing an idea into the pot.

---

An excellent suggestion, used with DI water that should cover all the bases, don't use bleach, if you need an anti-biological it needs to be PH neutral, but you could run your coolant through a pond/aquarium UV unit on it's return to the tank to keep the biological load to a minimum or you could have a submersible UV unit in the tank.

Quote:

---

Originally Posted by Doddy

Something like ?

---

Yes, exactly like.

Some good ideas there, thanks everyone. Re using bleach: the body of the spindle is aluminium so there is a risk there, though Wikipedia says it'a not corrosive at 200ppm hence the limit of concentration there. At the moment I'm still using plain old distilled water with no signs of an ominous green tinge.

Re the use of switches, thermostats etc for turning pumps on and of: my 240v pond pump is quieter than the VFD fan so I simply have it on the same mains supply switch. If the VFD is on, the pump is on. After a long cut yesterday for levelling the machine bed I found the tool and spindle shaft quite warm. I turned the pump off and the lower body of the spindle warmed up noticably so I turned the pump back on and it cooled almost immediately. This makes me more certain (as I said in the other recent thread about switching pumps on and off) that leaving the cooling on continuously during a working session will help cool the spindle faster after one cut and so reduce the starting temperature for the next. And it's simpler to implement. KISS!

Kit

Again, an off the wall suggestion, to inhibit algal growth how about a phenol based disinfectant, like Jeyes Fluid ? I do not know the pH properties of it though. You certainly would not need much.

Something else to consider, I'll look into it.

Having at long last got my machine into a state I'm hoping (with everything crossed) is going to prove workable and reliable for a reasonable period of time, I've finally tidied up, taken a photograph and given myself an avatar. The room is exactly 2 metres wide so the dust extractor is mounted high on the wall with the water tank underneath. Underneath that is a trolley with the controller (breakout board, stepper drivers and PSU in an old PC box) plus LinuxCNC computer. Cutting area is 940 x 640 mm.

Maybe we need a thread based on "what did you make with your CNC machine today?" There's no end of stuff on this website about the machines themselves but precious litle about what we all actually do with them!

Kit

Just a word of caution - phenol may attack and embrittle any plastic or rubber it comes into contact with.

My central heating header tank had a pint of cheap engine oil floating on top of the water to exclude oxygen. It worked well as it just stayed in the tank. Any oxygen in the water was soon boiled out.

Late to the thread but I’ve been using pc water cooling fluid for years and works fine. Lots on eBay such as EK-cryofuel.
Claim they are non toxic, don’t corrode wide range of metals, have anti fungicide etc.

Quote:

---

Originally Posted by routercnc

Late to the thread but I’ve been using pc water cooling fluid for years and works fine. Lots on eBay such as EK-cryofuel.
Claim they are non toxic, don’t corrode wide range of metals, have anti fungicide etc.

---

Of course ! Why did I not think of that, when most of the components I have for spindle cooling are out of a water cooled computer.

Quote:

---

Originally Posted by cropwell

Of course ! Why did I not think of that, when most of the components I have for spindle cooling are out of a water cooled computer.

---

Of course ! Why did I not think of that... as well! Though I've never water cooled a computer and I'm not using anything as swanky as a radiator in my system. Good idea.

Kit

OK, so I was about to buy 'Mayhems Biocide Extreme' additive especially for PC cooling systems when I spotted a warning not to use it in aluminium systems. Since the body of my spindle is aluminium this is no good. I think it's time to just stick with the distilled water and nothing else!

Kit

Quote:

---

Originally Posted by Kitwn

OK, so I was about to buy 'Mayhems Biocide Extreme' additive especially for PC cooling systems when I spotted a warning not to use it in aluminium systems. Since the body of my spindle is aluminium this is no good. I think it's time to just stick with the distilled water and nothing else!

Kit

---

The Chinese spindles look more like stainless steel to me. The end cap could be aluminium but the barbs go most of the way through up to the seal.

In any case the EK-Cryo fluid claims to be ok with SS Ali brass etc for corrosion and is not an additive. Just pour in neat.

I’ve used it for years without issues.
https://www.watercoolinguk.co.uk/p/E...SABEgLHY_D_BwE

Mine is SS, I just run plain good old water through mine. All I do is just change it every now and then. I don't really see much point in using expensive cooling agents for such.

Just back from a few days digital detox at Point Samson. No CNC machine, no internet!

A lot of the PC cooling fluid appears to be incredibly expensive eye candy, all swirly pearl effect colours. My key concern was the water going green (on it's own) which hasn't happened so far, so I'm sticking with plain distilled water for now.

Kit