CNC/Laser Driver Setup

Bill Arnold

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The driver board that came with my original SO2 CNC is the gShield that has three drivers on it. One driver gets slaved on your X or Y axis (whichever has two stepper motors. The new BOB I got from J-Tech has four drivers: X, Y, Z, & A. The A driver can be strapped to slave from any of the other axes. Although I could use the A driver to run the second stepper on my X axis, I'm planning to use it for a rotary axis. Any other opinions on this?

Thanks, folks.
 

Brent Dowell

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Depends on how many amps I reckon. With my board, I could have wired both x to the same driver, but I'm sure I'd be pulling more than the max amps per driver. That's why I went the hardware route.

Another option is to use external stepper drivers and use and adapter board instead of one of the pololu drivers. That's currently an option I'm looking at.
 

Bill Arnold

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The J-Tech BOB has DRV8825 drivers that are rated at 1.5A continuous and 2.2A maximum. I'm using NEMA17 on the laser setup since there's very little load. To get consistent operation on the X axis, I had to increase the current to about 0.7A (based on the voltage divider test point).

I bought a second J-Tech BOB to replace the Arduino/gShield on my CNC in part because I'm having to run the drivers at about their maximum since I have NEMA23 steppers on it. The drivers on that setup were getting pretty hot, so I added a small fan blowing directly on them. Another reason for the change is to have four drivers so it's easier to incorporate a rotary axis.
 

Bill Arnold

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i plan on running the x and y axis as usual. but, since there is no z axis in my setup, i'll be running the rotary from the z axis.
I have a Z-axis on my laser assembly so I can adjust the focal point for different applications. Eventually, I'll have a Z-zero sensor to automate the process as it is on my CNC.
 
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