stepper drive A3979

[dobrodewed]

I have a stepcraft with A3979 microstepper drive chips rated at 2.5A. I want to add a second 48mm nema 17 to the y axis. Stepcraft says their controller is proprietary so no schematic. I see the easy drive by Sparkfun uses a A3967 which looks like it's the next size down. I wonder if I could swap the chip and have a similar driver curcuit? Does anyone know of a driver that uses the A3979, so I can use that schematic? I've read some of the posts on the A3979 and it seems they have thermal issues. Could I add a power output to the A3979 to boost its current rather than sending the outputs to the motor? has anyone tried to take the motor connections and run them through another stage to boost it? If so a schematic would be wonderful.

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[aarggh]

The A3979 is a fairly bullet proof and simple controller IC, you can check the datasheet for the specs, and you can certainly heatsink them without issue. If you want to step down to another variant like the A3967 you'd need to check the I/O pinout and that the power specs are the same, but you still have the issue of slaving the axis with two steppers.

Normally this would be done by the control software, are you using Mach3 as this is supported by it, as long as your using a 4 axis controller, or 4 x individual drivers with a breakout board.

Doing it via circuitry would be problematic for a number of reasons, and in most cases I wouldn't think it worth the effort?

What issues are you having that make you want to add another stepper to the axis? Could these issues be solved by changing the mechanics or any of the components without resorting to slaved steppers?

cheers, Ian

[dobrodewed]

The A3979 is a fairly bullet proof and simple controller IC, you can check the datasheet for the specs, and you can certainly heatsink them without issue. If you want to step down to another variant like the A3967 you'd need to check the I/O pinout and that the power specs are the same, but you still have the issue of slaving the axis with two steppers.

Normally this would be done by the control software, are you using Mach3 as this is supported by it, as long as your using a 4 axis controller, or 4 x individual drivers with a breakout board.

Doing it via circuitry would be problematic for a number of reasons, and in most cases I wouldn't think it worth the effort?

What issues are you having that make you want to add another stepper to the axis? Could these issues be solved by changing the mechanics or any of the components without resorting to slaved steppers?

cheers, Ian

stepcraft sets their x and z to 1.4A and y and a to 1.8A via resistor size. Does anyone know what resistor values would do this? Is there a schematic? I'm just wanting to increase torque to those axis'. the specifications say 2.5A. I'd like to up them to 2A. I have the forth axis connector. Can I purchase a large driver (4-7A), place 2 steppers in parallel and drive them that way?