[bgasser]

I have a water cooled spindle on my cnc. The cnc is in my garage without any heat. Generally it does not get below freezing in there but this weekend it is supposed to be about 6 below 0 F.

Using rv fluid for cooling the spindle, should i turn everything off or would it be ok to leave it on?

Thanks

BenG

[1Jumper10]

I used an antifreeze solution just like a car uses in my water cooled spindle and it survived several sub freezing winter months in an unheated pole barn. That being said, water cooling was more trouble than it was worth. My machines all used 3hp 24krpm water cooled spindles. They never generated enough heat to even get more than slightly warm. And I had to pre-heat the radiator on really cold days to warm it or the bearings would protest if I ran full speed before it was warmed up. Air cooling would have been just fine.

[joeavaerage]

Hi,
the downside of air cooling is that you are even more restricted with regards running at part speed.

With a water cooled spindle running at 1/4 speed (6000rpm for a 24000rpm rated spindle) is acceptable, if not desirable. An air cooled spindle is very likely to overheat and wreck itself
at the same speed. I pretty much refuse to tun my air cooled spindle at less than 1/2 speed (12000rpm for a 24000rpm rated spindle).

Some of the top brand spindles that are air-cooled, HSD comes to mind, have a separate motor for the fan so that running at part speed is less likely to be detrimental to the spindle motor.

Craig

[Formantjim]

I too have been using a water cooled spindle on my DIY machine in my garage for over 5 years and use normal antifreeze coolant and it works fantastic. I live in Canada where currently in my garage it's -6C and I will be machining tomorrow so I let the spindle run for at least 5 mins to warm things up a bit.

[1Jumper10]

One member of this forum built a DIY wood structure machine with a water cooled spindle but ran it dry. I believe he ran compressed air through the water jacket and he didnt have any problems. I cant remember his username but I remember his machine. If I did it again I'd use this method. The spindles are super efficient, they dont generate much heat.

[joeavaerage]

Hi,

The spindles are super efficient, they dont generate much heat.

Until you ask the spindle to deliver high torque....then it gets hot....real hot.

Most of use only a very small proportion of a spindles potential output and you might be tempted to believe they are 'super efficient' but they are not.
The real test comes when you want to spin a tool to cut steel. In order to get decent tool life you need to spin it slowly, typically 1/4 of the speed you might use for aluminum.
Steel is tough and requires a lot of torque to 'peel' of chips. This is the weakest point of hobbyists highspeed spindles....they are made for high speed but low torque, but cutting steel requires
low speed but high torque. Thats when a spindle will get hot....real hot.

Craig