I recently learned about the sound advantage of water-cooled spindle over air-cooled router.
Anyone got links to ones you might suggest for Primo? Amazon links would be ideal (since I have prime) but not absolutely necessary if you have a good suggestion elsewhere!
Someone’s got a really cool CNC build that he can transport around. He’s running a water cooled spindle so it’s quieter when he’s doing demonstrations. I’ll see if I can find the link…
@stevempotter has a bunch of posts on his portable CNC so he may be able to help you with that.
I highly recommend the water-cooled spindle for a number of reasons.
It is quieter, more powerful, and I don’t have to worry about brushes wearing out, or vents that get clogged with sawdust. It is very heavy and I used a single-start leadscrew for the Z so it would not drop when the power to the stepper goes off.
Here are videos about my build:
and
Here is what I wrote to one query in the YouTube comments about the spindle:
This is the item I got from Daedalus Machine Tools Store on Aliexpress: YL620-A VFD and 8A 400Hz 3-phase water-cooled spindle 65mmX200mm Jhong Hua Jiang mark. [https://www.aliexpress.com/item/4000570392908.html (230V option with the collets). There are many other vendors of identical and similar spindles. Read reviews and descriptions carefully. I can say that this vendor packed it well and did help me with figuring out how to configure the braking resistor I later got. Value for money is excellent. I also got more flexible clear vinyl tubing, quick-disconnects, a flow indicator, 4-conductor shielded flex cable (16AWG), aircraft connectors, and I installed a ground (earthing) wire to be able to use a Z probe touchplate. You may wish to get a spindle with a larger chuck. This set can use up to 7mm diameter (0.3125 inches) bits.
Today I received a CPU water cooling system that runs on 12V, instead of the 230VAC immersion pump I got with the spindle. I think that will do fine.
One thing to note, and is pretty common for WC spindles: the VFD. That’s another significant hunk of electronics added to your system. It’s not an issue, per se, but it is something to keep in mind. You can’t just plug the spindle into your power strip. And don’t forget the extra plumbing for the water lines. It’s kind of obvious, but thought I’d point it out.
I hope I’m not sounding like I’m trying to dissuade you from going for a water-cooled spindle. I just want to make sure you’re jumping in with eyes wide open. 
Thank you for sharing the details. Not sure if I’ll ever get off the fence on buying a real spindle to replace my bosch router, but this will certainly help when/if I get around to that.
I did watercooling on my PC back in 1999… was not a very fond memory TBH. It took a heck of a lot of work building the DIY setup, and I never achieved the higher clocks that could have justified all the extra work. So I had a lot of apprehension when my good friend suggested I look at water cooled spindles as we discussed upgrades from my router.
However in this case there may well be enough real benefit to justify the added complexity. On the downside, besides the obvious complexity, hazard, and maintenance issues, water cooling adds more weight to sling around above the gantry. The noise argument in my case is not much a benefit, since my dust collector and/or air compressor already bring the noise floor way up. Even the fan clogging with dust wouldn’t be an issue for me since my dust extractor recovers 99% of the chips anyways.
However, longer brush life does sound appealing. Does the watercooling help with brush heat a lot? I haven’t seen details on how they are constructed, but I figured most commutators and brushes don’t lend themselves well to heatsinking. OTOH washing them with air will pull some heat away. Without that air, the conduction path between the comm/brushes and water jacket would have to be really good to compensate (air cooling by comparison is much easier to engineer/construct). I would not be surprised if water does help a lot with brush life, but I’d like to see the details of what they did to optimize heat transfer… cause if they did a crappy job on the design/execution then such watercooled spindles may get the brushes hotter than air cooling would.
A water cooled spindle is a synchronous (3-phase) motor: no brushes at all. No commutator. Water flows all around the stator coils, and near the bearings. Yes, a VFD (variable frequency drive) is another bit of kit to mind (it plugs into the mains), but mine has been trouble-free and was very cheap. Two more pluses of going with a VFD & spindle (in addition to more power and much quieter): 1. you can have full power at lower RPMs, which is good for cutting metal. And 2. You can stop the spindle in 1 second with the proper braking resistor and VFD settings. That is a safety feature that comes in handy when the bit is diving into something it is not supposed to. With a VFD, I have much finer control of speed (RPM) than with the knob on my deWalt router, and can vary it with gcode on the fly while in the middle of a job.
Liquid CPU cooling systems have really come a long way since the 90s.
I believe the VFD will also allow reversal of spindle rotation.
Ah, I forgot that most of those spindles use squirrel cages; watercooling can be very effective on those. The lower RPM torque, accurate RPM, gcode spindle control, and perhaps at some point reversibility are all certainly welcome on my mpcnc. There are so many watercooling components available these days… I figure most setups intended for PC watercooling would be adequate, since it’s not keeping silicone in check.
Steve, just FYI the URL on that Ali link you posted above goes to a dead YT page. I did find the ali page though, and noted the price with shipping is $258, plus $10 extra with a set of collets. I was hoping to find an option to purchase from Amazon but no luck in my greps… anyone find it available there?
[edit: I found a “MYSWEETY” (lol @ the branding) spindle on amazon that looks to be the same thing, but a $100 premium for it and I have only found it in 110V:
]
110 would definitely be more convenient, but I imagine the 1.5kW claim for both the 110 and 220 may not be correct. Seems the 220 would have an advantage in performance at the collet anyways. However, with watercooling do you guys think 110 would do about as good?
Fixed the link above! USD215 for the whole kit - amazingly cheap.
What is a squirrel cage?
That is cheap… and tbh I am in no rush so Ali is likely where I will go.
Squirrel cage is just slang for a 3-phase induction motor… what industrial engineers around here like to call them anyways. I think the reason behind that is a lot of diagrams used to teach how they work, have the rotor drawn in a way that resembles a rodent exercise wheel (aka squirrel cage).
Well the active parts of the rotor DO look like that, can’t blame the drawings 
I have heard of rust issues with these cheap oriental spindles so I would open them up to check and lubricate the bearings every once in a while. E.g. don’t trust the seals, use enough grease to keep it healthy.
Looks like Daedalus isn’t selling the kit any more, but here is a search that turns up other identical kits.
Has anyone disassembled such a spindle motor? I have one and the water can not flow anymore. I do not know how to open the motor to find out what is the problem and if I can fix it. Pictures from a disassembled one would be very nice … 