Can’t get any torque out of light object z table stepper

Machine: OMtech K40

Board: LaserBoard

Firmware: Smoothie

Problem/ Question: I can’t get the stepper to drive any load with the lightobject z table. I have followed the cohesion3D z table setup instructions and verified the wiring. It will turn with no load but barely any resistance and it just clicks/ratchets. I have tried up to the board max of 1.2A and it seems better but still not enough. The motor appears to be a Nema 17 48mm, online it’s hard to verify but I saw specs either at 1.2A or 2.0A. Do I need an external stepper driver?

Tried to add a picture but it wouldn’t let me. The tag on the side reads ZL42HS03 and that what appears to be a theta symbol followed by 5.

I’ve seen others successful on here with the light object table but their motors had different color wires. It now comes with red blue green black wires. Wondering if they changed the motor to something beefier???

Any help appreciated.

Yeah - definitely a NEMA17 rated at 1.2A. You should not need an external driver for this motor.

Doublecheck the coils are wired properly. It seems like you have them wired A+A-B+B- to A+B+A-B- or something from your description of how they’re working. The pinout on the laserboard’s motor headers is B-B+A+A- left-to-right. You should be able to see which wires from the motor correspond to each coil pretty easily - any pair of wires you get a low resistance on will be a coil. Connect one coil (it doesn’t matter which) to B+ and B- and the other coil to A+ and A-. If you find the motor is turning the wrong direction swap B+ and B- or A+ and A- (but not both) and it will start moving the right direction.

Good luck - hopefully you can work it out. If it’s still not working after you verify the connections post again for next steps.

Thanks for your help. I am still scratching my head here though.

Here are my steps this morning:

According to Lightobject the motor is Green A+ Black A- Blue B+ Red B- .
Based on the pinout of the laser board I wired it up Red Blue Green Black (B- B+ A+ A-). I ran it and still experienced the same issue (pretty sure this is how I originally wired it also). So then I did some iterations (swapping back to the same starting point each time):

Swapped Green and Black - motor runs
Swapped Black and Red - Motor does nothing, clicks once.
Swapped Blue and Green - Motor does nothing, clicks once.
Swapped Blue and Red - motor runs
Swapped both pairs (Red/Blue and Green/Black) - motor runs

In none of these configurations did I resolve the issue (any tension and it just starts ratcheting/buzzing). The first (presumably correct wiring) seemed the best.

I used an ohmmeter and verified 2.0 ohms on each pair Green/Black and Blue/Red.

Here is my config: config.txt (28.4 KB)
I have tested changing the gamma steps per mm to 316.9 or 3169, as well as different current values.
I have speed in lightburn set to 1 when I am testing the Z table moves.

Here is a video showing the issue (alternating between tension and no tension on the belt or with my finger): https://youtu.be/acYS-M2qt4A?t=8

OK. So it’s definitely wired correctly (red blue green black). This is either a problem with the driver on the board or a problem with the motor itself.

Let’s rule out the board as the source of the issue:

In your config file there will be a section that lays out the following:

gamma_step_pin                               2.2              # Pin for gamma stepper step signal
gamma_dir_pin                                0.20!            # Pin for gamma stepper direction
gamma_en_pin                                 0.19             # Pin for gamma enable
gamma_current                                0.6                # Z stepper motor current
gamma_max_rate                               24000.0          # mm/min
gamma_acceleration                           2500             # mm/sec²

# A axis
delta_steps_per_mm                           157.5           # may be steps per degree for example
delta_step_pin                               2.3              # Pin for delta stepper step signal
delta_dir_pin                                0.22             # Pin for delta stepper direction
delta_en_pin                                 0.21             # Pin for delta enable
delta_current                                0.6                # Z stepper motor current
delta_max_rate                               12000            # mm/min
delta_acceleration                           1000             # mm/sec²

Swap all the values for gamma and delta, then move the wires for the stepper motor to the A port on the board. See if the motor has holding torque now. If it still doesn’t, then the motor is defective. If it does, then the stepper driver on the board itself is bad.

Try that and let me know how it goes.

Thanks for all your help. I ended up ordering another stepper on Amazon to help troubleshoot and it worked perfectly the first time I wired it up so it wasn’t the laserboard (or me)!

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I also got a response from Lightobject that the stepper motor I received with the kit cannot be driven by the LaserBoard and requires an external driver. I don’t know if it’s worth updating the z table article with a note that it may no longer work without a separate stepper driver.

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