Author Topic: Water cooler for my spindle  (Read 1857 times)

Offline Myrickman

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Water cooler for my spindle
« on: December 31, 2019, 12:22:00 pm »
The pump supplied with my Chineseium spindle was a waste of $$$$...no way I’m dunking it ungrounded in a pail of water. Here is what I came up with using a condensate pump for HVAC systems and a bone yard auto heater core. The pump float switch is bypassed so it runs continuously and some plastic plugs prevent evaporation. The heater core is simply angled to it can get some convective air flow. I’ve run this for several hundred hours with no issues on my 2 hp spindle. Coolant is 50/50 antifreeze and water. Tubing is 1/4” Tygon. Total length of tubing is like 10-12 feet out and back to the spindle with a ~30” head to pump against. The pump has about a 2 quart sump also.

Offline Bob La Londe

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Re: Water cooler for my spindle
« Reply #1 on: December 31, 2019, 15:18:30 pm »
A centrifugal pump with the motor outside the coolant tank works great as long as the elevation difference is not extreme.  Typically people use evaporative cooler pumps, but commercial heavy all metal pump with longer shafts are available.  

Both the cheap cooler pumps and the more expensive commercial versions are intended for continuous duty. 
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If I have the time I'll be glad to show you a little in my shop. 

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Offline Bubba

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Re: Water cooler for my spindle
« Reply #2 on: December 31, 2019, 20:00:15 pm »
Bob,
It look like nice practical setup.
My 2¢

Win10 (64 bit, CB(1.0)rc 1(64 bit) Mach3, ESS, G540, Endurance Laser.

Offline Bob La Londe

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Re: Water cooler for my spindle
« Reply #3 on: December 31, 2019, 23:37:18 pm »
Bob,
It look like nice practical setup.

Looks nice, but a condensate pump is not intended for continuous duty, and I think 2 quarts may be a little low on the volume if he cuts any extended time jobs. Even a cheap low end water cooled spindle is a couple hundred dollars.  Make it last as long as you can. 

Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

Some Stuff I Make with CamBam
http://www.CNCMOLDS.com

Offline pixelmaker

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Re: Water cooler for my spindle
« Reply #4 on: January 01, 2020, 14:51:45 pm »
There is always a difference between "what is necessary" and "what do I want to play with".
The 2.2kw chinese spindle needs 20-26gal/h or 76-95 liter/h water according to the factory specifications.
The spindle is not directly cooled, it only has a double wall filled with water. Short-term high voltages which overheat the windings cannot prevent the water cooling, this is the disadvantage of the water-cooled spindles.
The advantage is that the toxic exhaust gases that are produced when the windings burn down remain in the spindle.

Important for the bearings of every HF spindle is a minimum temperature of 20°C.
Lower temperatures put extreme stress on the bearings and warm-up does not help.

Because the temperatures in my workshop are often much lower I have a 30l storage tank with aquarium heater. In this tank is an Eheim 1048-790 pump. It creates a flow rate of 90l/h with the used hoses 10/8mm in black.
The cooling water in the tank only heats up when I work at speeds above 18000rpm. If I work for hours at 24K rpm I have a heating of 0.5°C per hour. So even if the milling machine is running all day I hardly get over 30°C.
I only use tap water, because I use black pipes there is no algae growth. Once a year I change the water.

For the cooling system I only need the tank, the pump (10W/h) and if it is cold for 2-3 hours the heating (25W/h).
This is my minimum equipment, my first spindle ran with it for 9 years. I replaced it although it was not broken. My second spindle is now running for one year on the same cooling sytem.

Everything more and electronic gadgets might make the owner happy, but doesn't really help. With a closed cooling system there is no possibility of water heating to the minimum of 20°C. I have never seen a chinese spindle that broke because the cooling is undersized, but I have seen some with bearing damage because it was used too cold at the start.

greetings and all the best for the new year
ralf

Offline Dragonfly

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Re: Water cooler for my spindle
« Reply #5 on: January 01, 2020, 17:03:28 pm »
Very good point about the minimal spindle (bearing) temperature. I became a bit worried recently as the spindle body temperature before start of work is around 13-16°C this time of the year. In the warm part the temperature never got above 42°C with only 15l of coolant. I use antifreeze diluted for -10°C. To prevent algae and just in case the shop stays without warming for a longer time.

The additional heater didn't come to my mind.

Ralf, thanks for the clue.

Offline Bob La Londe

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Re: Water cooler for my spindle
« Reply #6 on: January 01, 2020, 17:37:19 pm »
15L is quite a lot more than 2 quarts.  About 8 times more. 
Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

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Offline Myrickman

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Re: Water cooler for my spindle- recommended spindle warm up?
« Reply #7 on: January 05, 2020, 13:12:18 pm »
Thanks Ralf for your experience and insight. While my cooler will effectively remove heat, it does not have the ability to preheat the water to the min temp. Can I free run the spindle at say 10k rpm for some time to warm it up? My basement shop runs at about 15C in winter...

Offline martyncnc

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Re: Water cooler for my spindle
« Reply #8 on: February 11, 2020, 13:46:29 pm »
I used a CPU cooling system from a gaming PC... keeps the spindle nice and cool and is designed to run for long periods. 5V supply. Easy and cheap to replace parts if they fail. It lights up blue when on so you can spot if it ever is not on. I've not had any major issues but there are probably lots of things wrong with this!

Offline lloydsp

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Re: Water cooler for my spindle
« Reply #9 on: February 11, 2020, 17:39:18 pm »
Add a cheap lift-pump immersion heater.  Most of them are adjustable as to temperature.

Lloyd
"Pyro for Fun and Profit for More Than Fifty Years"

Offline skysurfer

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Re: Water cooler for my spindle
« Reply #10 on: February 20, 2020, 13:40:35 pm »
Bob,
It look like nice practical setup.

Looks nice, but a condensate pump is not intended for continuous duty, and I think 2 quarts may be a little low on the volume if he cuts any extended time jobs. Even a cheap low end water cooled spindle is a couple hundred dollars.  Make it last as long as you can.  



I'll second that I tried a condensate pump and the motor became smoking hot after a half hour of running. I'm running a 2.2KW my reservoir is a 24" piece of 3" PVC pipe capped on one end removable cap on the other (I haven't calculated the volume) and a small aluminum radiator (previously a compressor after-cooler) the pump is a little 24V job I found on ebay threaded directly in the side of the reservoir. I've spun some 1/2" tools at low RPM for hours doing 3D profile roughing and it hasn't broken a sweat. Low speeds <7000 RPM causes more heating than high speeds, at least with the way my inverter is setup.
Austin

Pump
https://www.ebay.com/itm/IP68-800L-H-5M-DC-24V-Solar-Brushless-Motor-Hot-Water-Circulation-Water-Pump-USA/293151721173?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
« Last Edit: February 20, 2020, 13:53:22 pm by skysurfer »