I completed the first pass at a closed system for the water cooled spindle and thought I would share some details for you.
This is by no means the final system, but it does work very well.
All the parts were mounted on an old plastic cutting board using flexible metal hanger straps.
Eventually, once the components have been nailed down, I will mount them in a enclosure that mates with my controller enclosure.
Lets start with the spindle connection.
I had a bunch of 3/16" latex tubing that was purchased from a pet store a while back, so that is what I used to connect to the spindle. It's very flexible and could be run easily from the spindle back to the electronics.
There is no dedicated flow direction for these connections. You can use any connector for water-in or water-out.
I believe the actual nipples are for 1/4" tubing, but I had problems with the the thickness of the tubeing not passing through the nipple cap. You could leave off the caps and use some small 1" steel tubing clamps.
For my tank I'm using a small 200ml acrylic tank I picked up on Amazon.
I'm using 3/8" vinyl tubing held in place with 1" steel tubing clamps.
On the intake (top) tube I use a brass adapter to convert to the 3/16" tubing that is connected to one port on my spindle.
On the output (bottom) tube a connect to pump intake.
You can fill the tank all the way to the top, which will help if you plan on mounting the tank on your Z-axis. The top bleed/filling hole has a screw in cap with a seal so it wont leak.
The pump is a very small 12v brush-less pump I purchased from Amazon.
The intake is connected to the output of the tank via a 1/4" hose stuck into a 3/8" hose as an adapter.
The output of the pump is connected to one end of my radiator via the same 1/4" and 3/8" hoses.
The pump is turned on and off via a relay in the VFD. A snakk 12V AC adapter is used to power the pump.
Please note that this pump is the bare minimum I would use for this setup, and may have to be replaced with a larger one If I move to longer tubing on my spindle.
Radiator and Fan
The aluminum radiator I used is available on Amazon. It supports a standard 120mm fan shown here.
One end of the radiator is connected to the output of the pump. The other end connects to the other spindle port via an adapter.
The fan shown here is only a 54CFM fan and does an effective job, but I will be replacing it with a fan with a little more capacity.
The fan is connected to a 12V AC adapter and.
I replaced the fan with a 74CFM fan and the system is much more effective. The fan can be purchased at amazon here: 74CFM Fan
The 120mm fan guards can be purchased here: 120mm Fan Gaurds.
I used three different hoses for my setup and as such, I needed to come up with adapters. I found that the 1/4" tubing fit snugly into the 3/8" tubing so all I needed was a small 1" steel tubing clamp to hold them together.
The same goes with the 3/16" latex tubing and the 1/4" vinyl.
Note that you can use brass adapters but these can be hard to find and expensive.
The Next Step
The system is up and running on one of my CNC machines so I will put it to the test. I can run my spindle at high RPMs for several hours and the spindle temperature will stabilize at about 85F.
I purposely kept things a little simple so I could change the configuration at will. I think the way it will work out will depend on how I plan on mounting my pump, radiator, and tank. The system shown here would probably be adequate for a Z-axis mounted system, but for an off machine mount with several feet of tubing, a larger pump may be needed. After some testing we shall see.