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IndustryArena Forum > CNC Electronics > Stepper Motors / Drives > Selecting drivers but unsure about voltage

1. ## Selecting drivers but unsure about voltage

Hello,

I recently got a mill that was professionally converted to cnc. It has been sitting for years and nobody knows what happened to the electronic components and I am trying to figure out exactly what I need. I am hoping that I can use the slo-syn m111-fd12 stepper motors without having to get the slo-syn ss2000 drivers. It is a knee mill with a 7x28 table that is for personal use and I am not concerned with having high speed rapid movements.

After doing some reading on the geckodrive website and comparing to a spec sheet I found online I am unsure of the voltage requirements.

MC SUPPLY CO: Bodine Electric Co, KB Electronics, Brake Motor, Stepper, Gearmotor, Gearboxes, Clutch/Brake (M111-FD12 is the 1st one in the table)

I checked the wiring and found that the motors are wired in bipolar series. Using the geckodrive equation of 32 x sqrt(L) with an L of 9.2 Mh I get 97 volts. They also have a rule that you should never go more than 25 times the rated voltage of 3.2 or 80 volts.
At the bottom of the spec table it also states "(1) With 24 volts drive."

Should I be looking at supplying the motors with 24, 80, 97, or some other voltage?

If I calculate unipolar I get 48.5 volts using an L of 2.3 or a max voltage of 25 x 2.26 = 56.5 volts

It makes sense to me that depending on the way you wire the motor you run higher voltage and lower amperage or lower voltage and higher amperage but that 24 volt comment at the bottom of the table is confusing me.

I am hoping that I am understanding the write up on geckodrive correctly and any advice would be appreciated.

2. ## Re: Selecting drivers but unsure about voltage

Hi Tom - Steppers operate in "steps" self explanatory. Each step requires a certain amount of current to get to the next step. It is not a P=VA relationship to step the motor its a flux density which is proportional to current. So each coil is rated and should be run at its correct current. Now as the motor runs faster it generates a back voltage that has to be overcome. This means the higher the voltage the better. So run your motors at the highest voltage possible from your controller and at the correct amps. 24V is usually the minimum and higher is better 48V or more. Cheers Peter

Thank you