One Z stepper runs backward

LowRider CNC Troubleshooting
1

I’m just completing wiring my LR3 and testing steppers. SKR board. When pressing Z+ movement, one Z stepper runs CW, the other CCW. Swapping the two stepper cables causes the one that was CCW to be CW, and the one that was CW to be CCW. Wires are connected the same on both.

On a hunch, I swapped the driver from the backward Z stepper to the X stepper. Now the X stepper runs backward. And, yes, I tried flipping the stepper connector around the other way on the board. When I do it doesn’t work at all.

Could the driver be bad?

2

You can also try to change the direction in the firmware. Don’t ask me how since I am using a different one, but it should work.

4

Does this happen in both +Z and -Z directions or does the ‘backwards’ driver only go in one direction? Is there anything visibly different about the drivers?

5

It happens both directions.
In the + direction, Z0: CW, Z1: CCW
In the - direction, Z0; CCW, Z1: CW

6

When you say Z0 and Z1, that’s with the drivers in one configuration (driver 1 in the Z0 position, driver 2 in the Z1 position) and then if you swap the drivers around (driver 2 in the Z0 position, driver 1 in the Z1 position) it becomes the opposite of the above?

7

Yes - that’s correct.

8

That’s definitely bizarre. Perhaps try swapping the X or one of the Y drivers into those positions and seeing if that changes things?

If it were the SKR firmware doing it, I’d expect that it would stick with the position of driver socket and not follow the actual driver around.

9

On my Manta Board it was, ! to indicate reverse polarity.
Y
dir_pin: PF11
Y1
dir_pin: !PD6
Would reverse the the motor for Y1.

When I swapped to the Jackpot I had to roll the leads and I was in the same situation as you. It did take about six tries to get thing all moving in the right direction.
Then I figured out its :low on the Jackpot to reverse the motor.
direction_pin I2SO.12:low

10

The problem seems fo follow the driver, so that is definitely a good clue that it is the driver.

Swapping two pins or reversing the entire motor connector should reverse the direction. If the motor doesn’t move, that is weird.

You can dig deeper. You can look at M122 or try to measure the voltage on the dir pin. But I doubt you will anything besides the driver is broken.

11

As you can see in my OP I swapped the backward Z with X. When I did that a + move on X went in the - direction, and a - move when in the + direction.

I have a new driver on order. Should be here tomorrow. I’ll see what that does.

1 Like
12

Maybe it’s just me… but I would just turn the motor connector around (4321 instead of 1234) and call ot a day. So something like this may have happened to me, and I just assume that I wired something different…

It would be a different story if it were ignoring the direction pin (+axis moves -, and -axis moves -) but reversed? Like I say, I’d just figure it was something that I did.

I guess it’s possible that you got a different manufactured driver board that has something swapped in the circuits (A1, A2, B2, B1 instead of A1, A2, B1, B2 on the motor output pins?) I have seen the pins labelled both ways on stepper boards…

13

I know of that approach and I had tried it but when I did the motor would not run.
I tried it again this morning and lo and behold, everything is fine!
Guess I can cancel that stepper order.

2 Likes
14

Sounds like an intermittent wiring issue. Loss of one of the 4 motor connections would result in only one of the pairs of driving coils being energized, which might result in motion in one direction and no motion in the other.

I’d make sure the pins were well seated in all the connectors for that motor.

15

This same thing happen to me, but I took pictures every time I moved the leads. With each test I did get a stepper response. (wrong direction, or stepper buzz.). After 6 tries I ended up with the same wiring as in my second test, and everything worked. I didn’t say anything here as it’s the same as saying bigfoot, or aliens helped me fix it.

So remember to keep repeating the same thing over and over, eventually you’ll get different results. :crazy_face:

16

Reminds me of the definition of insanity.

1 Like