Bt30 spindle from aliexpress

Planning out my next machine build and I'm hoping to get some advice on the spindle. I plan to drive a bt30 cartridge with a dmm 1.8kw servo. There's quite a few options for cartridges on aliexpress for decent price. They come ready to go with spring washers, petal clamp, etc. Price goes up relative to max rpm they can handle, which I assume is mostly a difference in bearing quality and balancing. Anywhere from 5k max to 14k max. Price from a few hundred to 1500. Since I will be working in mostly aluminum with smallish parts, I want all the rpm I can get. When I started searching for a spindle, 12k was the fastest available with a price of 1250. I contacted the seller and said "12k will be good, but do you have anything faster? Like 14k?" His response makes me a bit nervous. He said "sure, here is a 14k max spindle". He also provided a link that took me to a listing that looks identical to his 12k rpm max spindle. Only difference being that the max rpm spec was 14k and the price was 130 bucks higher. This listing did not come up previously when I was searching. It makes me a bit doubtful that his "14k max spindle" is any different than his 12k spindle and hes just telling me what i want to hear to get a sale. Maybe I'm being paranoid.

Does anyone else have experience with one of these bt30 spindles from aliexpress? I'm obviously not expecting top notch stuff for that kind of money, but I would at least hope it should perform as advertised for a couple thousand hours or so.

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Originally Posted by QuinnSjoblom

Planning out my next machine build and I'm hoping to get some advice on the spindle. I plan to drive a bt30 cartridge with a dmm 1.8kw servo. There's quite a few options for cartridges on aliexpress for decent price. They come ready to go with spring washers, petal clamp, etc. Price goes up relative to max rpm they can handle, which I assume is mostly a difference in bearing quality and balancing. Anywhere from 5k max to 14k max. Price from a few hundred to 1500. Since I will be working in mostly aluminum with smallish parts, I want all the rpm I can get. When I started searching for a spindle, 12k was the fastest available with a price of 1250. I contacted the seller and said "12k will be good, but do you have anything faster? Like 14k?" His response makes me a bit nervous. He said "sure, here is a 14k max spindle". He also provided a link that took me to a listing that looks identical to his 12k rpm max spindle. Only difference being that the max rpm spec was 14k and the price was 130 bucks higher. This listing did not come up previously when I was searching. It makes me a bit doubtful that his "14k max spindle" is any different than his 12k spindle and hes just telling me what i want to hear to get a sale. Maybe I'm being paranoid.

Does anyone else have experience with one of these bt30 spindles from aliexpress? I'm obviously not expecting top notch stuff for that kind of money, but I would at least hope it should perform as advertised for a couple thousand hours or so.

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When you get up to those speeds with any Spindle that uses Grease for lubrication, what Bearings are used is going to make the difference as to how well it will last it is right at the max for Bearings that are Grease Lubed, oil mist and you can go higher

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Originally Posted by mactec54

When you get up to those speeds with any Spindle that uses Grease for lubrication, what Bearings are used is going to make the difference as to how well it will last it is right at the max for Bearings that are Grease Lubed, oil mist and you can go higher

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How will I know if I'm getting beyond the limit of the spindle rpm? If I monitor temperature of the spindle and have the machine alarm out at a certain point, can I protect the spindle and keep it within it's limits? I'm not sure I feel safe just trusting that an aliexpress spindle can run at 14k rpm for hours and not eventually reach thermal runaway and blow up. I will be running long programs unattended. Am I safe if I use temp sensors with alarm? I'll be designing my own headstock so i can use a couple sensors and position them right at the bearings.

Also to add to that, can I increase the rpm limit of my spindle with active cooling in the headstock?

Quote:

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Originally Posted by QuinnSjoblom

How will I know if I'm getting beyond the limit of the spindle rpm? If I monitor temperature of the spindle and have the machine alarm out at a certain point, can I protect the spindle and keep it within it's limits? I'm not sure I feel safe just trusting that an aliexpress spindle can run at 14k rpm for hours and not eventually reach thermal runaway and blow up. I will be running long programs unattended. Am I safe if I use temp sensors with alarm? I'll be designing my own headstock so i can use a couple sensors and position them right at the bearings.

Also to add to that, can I increase the rpm limit of my spindle with active cooling in the headstock?

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See if you can get it with ceramic Bearing then if it does not already have them, and you should not have any problems, cooling can always help

If you want high rpm for cutting small aluminum pieces wouldn't you be better off with a decent router spindle motor.
With the price of a bt30 spindle, servo motor and driver you could get a good router spindle like a tekno motor or similar. They can cut ally great, have air tool changer and would be less work to mount it to your z axis.

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Originally Posted by v2tiller

If you want high rpm for cutting small aluminum pieces wouldn't you be better off with a decent router spindle motor.
With the price of a bt30 spindle, servo motor and driver you could get a good router spindle like a tekno motor or similar. They can cut ally great, have air tool changer and would be less work to mount it to your z axis.

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Yes, you're absolutely right and I'm still on the fence about it. Currently I'm running a 2.2kw Chinese spindle and it does amazing in aluminum. My next step is to have an automatic tool changer and the 2 options im considering are a bt30 servo driven spindle or an all in one atc unit like you mention. Like you said, the atc unit makes things extremely simple and easy to put together, as well as being even faster at running aluminum parts than the 14k bt30. As awesome as all that is, there are huge drawbacks with the atc unit where the servo driven bt30 really shines. Low rpm capability, and synchronised operations like rigid tapping. With the servo driven bt30, I can run big facemills, boring heads, decent size drills, rigid tap, hob gears, etc. It has crazy good torque all the way down to zero. Also I can orient the spindle for tool changes which allows me to clock tool holders for very repeatable run out and hold very tight tolerances on my parts. In the end the only functional disadvantage of the bt30 is top speed and I think it's worth giving up for all the other features. That being said, still a hard decision.
In the end I will have 2 milling machines. One with the atc unit that is geared for high rpm that will cut mostly carbon fiber, and another more versatile machine with the bt30 on it. For now just having a hard time deciding which to do first. Right now I have only one machine that I am using for everything, a pretty heavy duty gantry layout that is beefy enough for either spindle once I make a couple changes including a new epoxy granite base.