Spindle Speed Controller Question

[Ger21]

I've used high quality air cooled spindles for years with no issues, running 8-10 hours a day, 6 days a week. HSD spindles with electric fans for over 10 years at a previous job.
At my current job, we have a 10HP spindle that's cooled by the dust collection airflow. It's been running full time for over 8 years now.

I own a couple air cooled chinese spindles, but haven't used them yet to see how long they'll last.

[JAZZCNC]

I've used high quality air cooled spindles for years with no issues, running 8-10 hours a day, 6 days a week. HSD spindles with electric fans for over 10 years at a previous job.
At my current job, we have a 10HP spindle that's cooled by the dust collection airflow. It's been running full time for over 8 years now.

I own a couple air cooled chinese spindles, but haven't used them yet to see how long they'll last.

Yes Gerry but that's not comparing Apples with apples. High quality Air cooled HSD spindle is different Animal to the cheap Air cooled what's been talked about here.
In my experience at the price level of the WC spindle NOTHING comes close to comparing and only fool would buy Air cooled at or very close to same money has WC.

[Rye]

I have a shonky Chinese 6040(any luck i'll be upgrading soon) that's falling to bits at the seems, but the 1.5kw WC ER11 spindle works a charm. Often have it running for 8 hrs solid and it only just gets warm to touch. Very quiet too - although the same can't be said for my pump(gets hot and sounds like a foghorn; anyone recommend a relatively cheap and "silent" one from ebay UK, would be grateful.) Would definitely recommend a WC over an AC - but get one with a larger collet than ER11.

[Neale]

I use a Whale submersible pump, designed as a pressure pump for fresh water for caravans, etc. Says max run time 15 mins at 12V, but I use 12V to purge the air at the start of a session then switch to 5V and it runs silently and happily for hours on end. Sits in a bucket of water and connects via cheap pvc tubing. Cost about a tenner, about 4 years ago, and still running fine.

[A_Camera]

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.

[A_Camera]

Yes Gerry but that's not comparing Apples with apples. High quality Air cooled HSD spindle is different Animal to the cheap Air cooled what's been talked about here.
In my experience at the price level of the WC spindle NOTHING comes close to comparing and only fool would buy Air cooled at or very close to same money has WC.

Only a narrow minded fool does not understand that different people have different needs. Money is not an issue in my case, has NOTHING to do with why I prefer air cooled.

[A_Camera]

I've used high quality air cooled spindles for years with no issues, running 8-10 hours a day, 6 days a week. HSD spindles with electric fans for over 10 years at a previous job.
At my current job, we have a 10HP spindle that's cooled by the dust collection airflow. It's been running full time for over 8 years now.

I own a couple air cooled chinese spindles, but haven't used them yet to see how long they'll last.

Air cooling in itself is not negative, except in the narrow minds of some people. Water cooled is a buzz word among hobby CNC machinists today, everybody wants it regardless if they really need it, and some preachers are chanting about it like if it was best thing after sliced bread. As far as I understand, the only real advantage of water cooled spindle is the possibility to run the spindle at very low speeds, and/or for very long periods non-stop. On the other hand, if that is necessary then these cheap Chinese 24k RPM spindles are the wrong choice anyway. Many people use spindle noise as an argument, but that is only valid for those who are always milling air. Blowing around of dust may be an issue for those milling MDF or wood, but that's only an issue for those who don't have any dust extraction, which in my opinion is just as important with water cooled as it is with air cooled spindles, at least if you are milling wood or any other dusty material. Yes, the fan inside can break, but so can even the cheap bearings (which is more likely to break at high speeds) or the water pump, or the water sealing gaskets inside the spindle or the joints or whatever else.

BTW, I checked at the HSD spindles and interestingly, most smaller power air cooled have the same kind of built in fan as the cheap Chinese spindles we are talking about. Only a very few have active cooling with electric fans. Also interestingly, most of their motors have a large gap between rated and maximum speed, so calling these cheap Chinese motors 24k RPM motors is a bit wrong, even here, regardless if we talk about the water or air cooled ones. I think my assumption earlier that these cheap motors should not be run at speeds higher than 18-20k RPM, at lest not for long, was about right if even the more expensive ones have 18k rated RPM. Yes, they may work at 24k as well, but they are not designed for that. So, while water cooled has it's advantages, I don't think it is necessary for everyone, and definitely not for me. I have used my air cooled DC motor for about a year now, and never once I thought "...oh, I only wish I had a water cooled spindle" so I should know and understand my needs by now. Never the less, if my current cheap air cooled spindle would die, I'll have a closer look at HSD, or some other quality air cooled spindles, so thank you for the information. I know the price is about the same as my CNC costs, at least for some of them, but hey, this is my hobby and we live only once...

[Clive S]

I see that you are still trashing this post by Thomas just like you did with the another one.

It is not good manners to take a thread so far off course why don't you start a thread of your own.

[Slixxor]

Hi Thomas,

I think when all said and done these motors/spindles are just a typical DC motor, so you can just give them 12-48v and your away.

I would imagine then that you can just vary the voltage supplied, to control the speed, you may be able to do this with a controller depending on what you've got, however it may just be better to get/use a standard type potentiometer where you control the speed manually.

I say the above because to be honest I wouldn't bother to invest any time or energy in one of those spindles, they work yes (they hold a cutter and spin) but their not really up to much at all, not sure if you've noticed or not but they are fitted with an ER11 collet, that's going to limit you to very small cutters for a start.

If your looking to fit it to one of these £4-500 Chinese machines, then yeah pop it on the machine and crack on making dust as you've nothing to lose.

If it's going on a machine that is much more capable then that is when I would say don't bother, the machine will be capable of more than the spindle will like and you'll just kill it or be limiting yourself/machine, it will just end up being a false economy is what I mean to say.

If you consider what is involved with adding a spindle to a machine (properly), it would be a much better investment of everything to use a more worthy spindle to start with.

The best price I can find a 2.2k water cooled spindle and vfd for is £180, they've sold lots, comes with a 2 year warranty but more attractive is the quote of 4 quality bearings in the spindle:

http://www.ebay.co.uk/itm/170746857178

I haven't ordered from them yet but I will be soon and I'm pretty positive that's who I will buy from, they do have negative feedback but I couldn't find any that related to this item.

As I said these spindles do work, here is a video of one actually cutting something:

https://youtu.be/6v534cJNzrU

.Me

A PWM speed controller would be much better for a DC motor. You will struggle to find a resistor that is rated high enough wattage wise to limit the current. Also, reducing the voltageis not a good idea as it will shorten the life of the motor. You're on the right track though.