Quote Originally Posted by JAZZCNC View Post
Why do assume because It's hobby most machines are run for short periods at time.? Just because you may doesn't mean others do.! . . Infact I can tell you thru my experience of building machines for Hobby people which are used in vastly different walks of life it's actually very common for machines to be run for extended periods in Hobby use. Single Jobs that take 8-10hrs cutting 3D models in very abrasive model board or MDF moulds etc. On large 3D Jobs this can 24hr+
Yes they may not do this every day or every week but at least they can if they wish to and not worry about killing there spindle. Which isn't the case with Air cooled spindle. Run it for 24hrs none stop at 24000rpm and it will Die.!!

Try that with Air cooled Spindle and see how long it lasts.? The duty cycle alone eliminates Air cooled Spindle. The dust just Kills the bearings Fans etc in short period of time. Which in practice on long jobs often doesn't happens because the heat Kills them first.!
(Stopping the spindle for cool down period isn't an option either because it leaves tool marks on the work piece.!)

Now we come to the Simpler Part.? . . . Really 2 hoses connected to pump in bucket isn't exactly Complex or rocket science. Or Like Boyan says and what is actualy happening on my machine at moment due to robbing the pump for another Job is straight thru the hose pipe and out again.
Other than this there is no difference. The advantages of WC spindle with VFD greatly out weigh any slight None complexity of the cooling system. And for No or very little extra cost.

For anyone building there first CNC Machine then buying a Air cooled spindle costing same or few £$ or euros cheaper than WC is Dumber than Dumby recommending to do so.!
ha... ha... ha... Why assume that EVERYONE uses his CNC in dusty environment for jobs which definitely classed as industrial work? Even if it is called "hobby" it is just as industrial manufacturing as any other professional work if you do such long runs. It's not me making assumptions, it is you and all the other people who lack imagination and can't understand that what suits your needs may not suit everyone else and what you may need may not be necessary or needed for others, and the environment you have around you may not be the same as everyone else have. That seems to be very difficult for some of you to understand.

Like I said before, if you use your CNC as an industrial machine, even if you have it as hobby, of course water cooled is to be preferred. If you run the spindle for 24hr+ jobs that in my vocabulary is called industrial use, and in fact, demands high quality parts, even for hobby and even if you have a water cooled spindle. If I would be planning for that kind of activity I wouldn't even look at cheap Chinese spindles at all, water cooled or otherwise.

As for 24h test run you propose, no, I am not going to test run my spindle for 24 hours non-stop at 24k RPM because such test is totally pointless, regardless of the outcome of it. Other than that, I think what most likely would fail is the bearings, and those bearings are the same in both water cooled and air cooled spindles if they come from the same factory. What I hear is that these spindles are NOT made for spinning at that speed, even if they can do that, because of the low bearing quality. I have no idea if that is true or not and not going to pull apart mine just to have a look. Also there are huge individual variations, some spindles die faster than others because of generally low QC. So, your proposed test of my spindle is totally pointless, but if you want you can send me one at your own cost and I can test run that one for 24+ hours and report about the results. In parallel, you could send me a water cooled one from the same factory with the same power so that I can run the two in parallel and see what happens. I can set up the water cooling necessary, have a pump I can use and all the necessary other parts for the cooling, so don't bother about that.

Other than that, I will use my spindle just the same way I want or need to. The longest run with my DC spindle was 1.5 hours work. It worked just fine and is still working. I expect the spindle I have now to last even longer and for at least the same length of jobs. I will not likely need to run my spindle at 24k RPM since I am currently pretty happy with 9-10k RPM, so even here, if I can double that to 18-20k RPM that's more than I need. Regarding the heat... well, don't worry about that, I am supervising the heat of not only the spindle, but also all my steppers, power supply and drivers. So far I have not seen heat as a problem the way I am using my CNC. BUT... if my air cooled spindle would die I would evaluate the reasons and if the reason is poor quality I will buy a new air cooled spindle of much higher quality and price and don't bother with the cheapo Chinese ones. But again, that's just me looking at my own use, need, environment and so on. Not necessarily the same or similar to yours and it may not suit you at all, but definitely suits me very well.