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50k RPM with DIY Motor? Answered

Has anyone built an electric motor that can reach 30-50k RPM? Would you think it is possible to build one?


Do you have a specific use in mind?

To build a spindle for a CNC. I could just buy one but I have been wanting to build a EM motor from scratch for some time. For it to function as a spindle I need for it to have an RPM of at least 30k. Doing some research, a DC motor would be the easiest to build. I have an idea of how to make it brushless without the use of a sensor/controller.

You want to run a CNC lathe at 30k rpm?

I keep finding various operating RPMs for CNCs. Initially 30k was average but now I am discovering spindles that run on 7k that can cut aluminium.

What would you suggest is the average RPM for a CNC?

There isn't an "average" speed, it depends on the diameter of the cutter and the material being cut, and the material doing the cutting. Some of my carbide tools, 16mm in diameter, cutting aluminium, will happily cut at 800m/min, which is 800/0.016/pi =16,000 RPM.

My close friend, in a neighbouring business has ballended milling cutters with a 1/4mm ball, these run at 150,000 RPM with an airspindle.

I don't know, it's just that 30k+ sounded high for a home-made machine - I could imagine small inaccuracies building up into mighty vibrations.

It took Dyson's team a decade to develop that. For DIY purposes it is not practical.

I guess you could experiment with rare earth magnets, vacuum and supercooling but then would it be practical to call it a motor that would spin really fast but not capable of being coupled to do some kind of work.