Stepper Motor Power Supply Size?? Calculator??

Hello, I am rebuilding an older CNC with slo-syn stepper motors. The specs for the motor are:

200 Steps per revolution
Holding Torque = 770
Voltage = 1.4
Phase Resistance = .200
Current = 7.0
Phase Inductance = 1.49

I have Gecko GR214V 7AMP drivers powered by a 48V power supply. The motors will heat up within 10 minutes of just sitting there, where I can not even touch them. I am concerned that they have told me to get the wrong power supply. I am new to this, so please bear with me. Is there a calculator to figure out what the correct power supply voltage should be? Or does anyone no what I should be using. I have a feeling this is too much voltage. Thanks!

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Originally Posted by tnwalkinghorse

I have Gecko GR214V 7AMP drivers powered by a 48V power supply. The motors will heat up within 10 minutes of just sitting there, where I can not even touch them.

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Stepper motors will heat up even "just sitting there", that's normal. And they do get pretty hot, that's normal too. If they get TOO hot, you can always lower the motor current using the DIP switches inside the Gecko.

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I am concerned that they have told me to get the wrong power supply. I am new to this, so please bear with me. Is there a calculator to figure out what the correct power supply voltage should be?

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The higher the better (within the driver's capability, which is 80V max for your Gecko). Higher voltage allows you to spin the stepper motor faster without stalling. Which means higher feed speeds and shorter machining times.

I also have a Shop Bot and can run a 4 hour job and the motor will barely go above room temperature. This is why I am concerned. It smells like burning wires and heats up way to fast. I lowered the motor voltage from 48v to 39v last night and did notice a slight improvement. The motor is constantly buzzing also. Should I lower the current to 6 amps? Thanks!

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Originally Posted by tnwalkinghorse

I also have a Shop Bot and can run a 4 hour job and the motor will barely go above room temperature.

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That means the motor current was set conservatively; you can safely increase it if you ever need to.

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It smells like burning wires and heats up way to fast. I lowered the motor voltage from 48v to 39v last night and did notice a slight improvement. The motor is constantly buzzing also. Should I lower the current to 6 amps?

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The smell of burning wires is definitely not good, you should lower the current until the motors assume more comfortable temperature. Leave the power supply voltage at 48V, you don't need to change it to control the current.

Like Citizen said, it's the current you are concerned about. For nearly all operation the stepper heat is resistive losses, I^2*R. No voltage component.