[tmbg]

Hi folks,

I'm working the spindle for my desktop mill, and I decided to play with a brushless DC motor that I picked up from a hobby shop. It's a big beast, designed for a 1/8 scale monster truck. It's 2200kv, max input 25V, and up to 120A current.

The documentation for it is pretty limited, it's along the lines of "plug this sucker into your monster truck and it'll be fast!" Great, thanks guys! What they do tell me though, is that my batteries should be able to deliver 75A continuous and 125A surge.

Well, obviously I want to use a power supply rather than batteries, but where the heck am I going to get a 125A power supply? Any thoughts on that?

I have a 20A 12v bench supply that I'm going to test with. I'm not sure if I need to run it at 24V or not. I'm not 100% clear on how these ESCs work, but I believe that if I run it at 12v I'll just get half the possible output speed. From what I've read, the Kv rating describes rpm per volt of input voltage (and that being the peak voltage on the phase windings). I also believe that the ESC will have an output voltage that does not exceed input voltage, so if I run with a 12v supply, I'll have no more than 12v phase voltage. That'd put my top RPM at 12 * 2200, or 26k. 24V would give me 52k rpm. The motor specs as max rpm 60k, so that sounds about right.

I'm also not sure what the torque vs input voltage curve looks like. I'm hoping that I can run it as low as maybe a volt, which would give me 2200rpm at the motor, and still develop acceptable torque. If so, I could do a 2:1 belt/pulley reduction, which would be easy to build, and give me a speed range of 1100rpm to 13k (or 26k if I get a 24v supply).

Anyway, anyone have experience dealing with these motors and ESCs and can shed some light on it?

[Larken]

You going to need a Brushless drive for that and It will have to be a high current, low voltage Vehicle type.

The other thing you could do is use a 3phase stepdown transformer in front of it and that would allow you to drive it with a standard VFD.

Larry K

[isvflorin]

Hi there,
read this whole thread, you should have a much better ideea after reading.

http://www.cnczone.com/forums/showth...haft+precision

[Zig]

The questio is willyou nee 2.2kW motor to run the spindle..if not then Your operating current will be proportionately lower.