Connecting Nema motors to the board

[Thijsnieuwenhuijs]

Hi everyone,

I'm currently building a large-format 3D printer using a BIGTREETECH Octopus V1.1 board with TMC5160 drivers (mounted directly on the board) and NEMA 23 stepper motors rated at 1.9 Nm holding torque (HWC-ST-2319SD8).

However, I’m facing a persistent issue:
Despite configuring the drivers for maximum current and using parallel wiring for the motor coils, the motors only deliver about 0.75 Nm of holding torque — far below their rated spec. This is verified through physical torque testing.

Hardware details:
Board: BTT Octopus V1.1
Drivers: Onboard TMC5160 (SPI)
Power supply: 24 V
Firmware: Marlin 2.1.x

What I’ve tried:
Verified coil pairs with a multimeter
Set current limit in Marlin to the motor’s rated peak
Tested multiple driver slots (Z, Z2)

Has anyone successfully used NEMA 23 motors with TMC5160 drivers on this board?
Is there anything I might be overlooking — for example, driver limitations, SPI config, or a Marlin setting?

I’d really appreciate any insight or experience you can share. Thanks in advance!

[bigtreetech]

Check the value of your Rsense. If it is wrong then the driver thinks it is delivering the needed current long before it actually reaches the needed current (or the other way around depending on whether it is higher or lower than reality).

Other than that, there is a limitation of an absolute maximum of 3A on each driver output port on the board and you would do well to operate within 80% of that. Pushing higher than that is work for the Kraken.

[zvonka]

I think you may be limited by the electrical transmission capacity of the header pins in the 2.54mm spacing format found on most 3dp connections. The matching female terminal for these male connectors are only rated at about 2 amps i think max.

You may have to use the octopus to just generate the step and dir signals &send them to discrete independent stepper drivers instead of board mounted 5160s, or any other board mounted driver