Re: [CAD_CAM_EDM_DRO] Miracle Motor

Hi Wally,

The big problem is heat. These motors are designed to be force air
cooled. They will work without force air cooling but at a reduced
output. You want the lowest winding resistance posible to reduce the
amount of heat generated. A motor that is designed for 260V is likely to
have considerably higher winding resistance than an equivalent one
designed for 130V.

The 2.5hp 130V motors may be twice the price but will work a lot
better. I ended up using the 110V 1.5hp motors on my mill simply
because they have a decent length of shaft sticking out the back to fit
an encoder on to. Item 10-1834 ($12.99) has a built in 200 line
encoder that can be fitted on to these motors with a little bit of work.
With 2.3:1 reduction these motors will throw my Bridgeport around at
silly speeds.

Les

cnc_4_me wrote:

>With the talk we have had lately about servo motors torque remaining
>constant ,and rpm being proportional to voltage. I expanded my
>search for servo motors to include higher voltage motors I did not
>consider before...The results are so startling I think they must be
>wrong.
>
>SPECS
>Treadmill motor from surplus center item# 10-2167
>2 ¼ HP at 260VDC
>1 1/8 HP at 130VDC
>95-260VDC
>5 amps
>0-5100RPM
>
>Calculated torque = 441 oz-in = 27.6 lb-in
>
>Assuming we are using an 80VDC supply. We are about 70% below 260VDC.
>RPM at lower voltage = 5100RPM x .3 = 1530 RPM
>1530 RPM / 2.5 pulley ratio = 612 RPM on screw
>612 RPM x .2" lead = 122" rapids
>
>And now for the kicker...This motor has a max current of 5
>amps...Our average current would be much less...And this is all at
>27.6 lb-in x 2.5 = 60 lb-in torque at the screw... FROM A $10.00
>motor...
>
>It just doesn't compute...
>
>Warning overload!!! Danger Will Robenson...
>
>
>Wally
>
>
>
>
>
>
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