TA8435H chinese driver board, current, torque

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Hello all,

Some time ago I got ambitious and bought various parts to build a XYZ table. It's located at a hackerspace / maskerspace we have started in downtown Norfolk VA.

I've been on and off with finishing it. I made the X travel around 48" long, which was probably too big. The motors are NEMA-23 sized steppers, using dual acme lead screws.

It seems as if I'm not getting enough power from my Chinese made driver board. It uses four Toshiba TA8435H drivers. I have two of them driving the separate motors for the long axis.

Using a bench power supply, I never see it draw more than .5 amps at any voltage.

Are the large ceramic resistors on the board current limiting? The data sheet mentions a .8 ohm 2 watt resistor connected to pins 18 and 21, The large resistors are green-black-silver-gold, which should put it at .5 ohm?

My board doesn't have any adjustment to change the current limit. Anyone know if it's possible to change the resistors to up the current limit? It's easy enough to fan cool the driver better. The board never really gets warm, the resistors do though.

The other thing I'm going to double check is how I have the motors wired up. I know they are 8 lead motors. Perhaps I'm loosing power here.



Is the driver board. It's not great, I know. For the moment I don't have money to put into this project so I'm just looking to make do with what I have.






This is my table. It's farther now with the motors mounted on the far end and the lead screws in place. It's not highly accurate and the lead screws were bent in shipping.

In the future I plan to scrap it and move to a smaller rig built out of 80/20 if I can find it used.

In the meantime, I'd like to make what I have work. I think the saying goes the first table is used to build the 2nd.

Any pointers are appreciated!