What do you do when the stepper motor driver is just not cutting it? In the case of BCN3D, you develop a completely new stepper motor module. After a month of studying different stepper motor control solutions to make their Sigma R17 printer silent and smarter, BCN3D decided to replace the Texas Instruments DRV8825 driver for the TMC2130 by TRINAMIC Motion Control.
Revamping the stepper motor module
According to Marc Cobler, Electronics Hardware Engineer at BCN3D, silence of operation and smoothness of the movements are the main selling points for additive manufacturing machines for the desktop. “People are going to have it at home and offices, so it needs to be silent and easy to use with the best possible quality.” Important features on which the previously used driver couldn’t deliver.
Once the solution was found in Trinamic’s stepper motor driver, it had to be adapted in such a way that the new driver module has the exact same form factor as the one already used in the successful Sigma R17. This meant that space was a challenge. Another challenge was time. Luckily, the TMC2130 stepper drivers can work in standalone mode with DIR, STEP, EN control interface, making it compatible with the Sigma’s interface. This allowed BCN3D to save precious time in both hardware design and firmware development – the plug-and-play solution was already working with the machine.
The first prototypes were designed within the next month, showing some issues with heat dissipation and layout. Two more prototypes were designed before the final design was finished and tested. All in all, it took BCN3D about 6 months from testing different solutions to implementing the new stepper motor module in the production chain with Trinamic’s ICs inside.
Eliminating defects of prints
The new driver not only results in silent motors. The TMC2130 allows for much smoother movements of the Sigma R17 printer as well, by having a 1/16 microstepping with 1/256 interpolation without affecting the microcontroller’s step rate generation. As such, the new stepper motor module implies that it prints products of a higher quality, eliminating visual defects in printed products.
This, in combination with stallGuard™ and coolStep™ to improve efficiency while reducing component costs, results in a significantly improved BCN3D Sigma R17 – one of few printers that can print with two materials independently.