The change of the stepper motor drivers surely is the most important improvement in the new BCN3D Sigma R17. The impact such a small chip can have on the behavior of the printer is incredible.
So far, we use to mount the Texas Instruments DRV8825 driver. It is commonly used in 3D printing because of its wide range of power but it’s very noisy and not very “intelligent”.
We immediately realized that we need to find an alternative and found the solution in Trinamic. Trinamic drivers are famous for their ability to move the stepper motors with almost no sound and with incredible smoothness. We can see some video examples here or here.
So we decided on the TMC2130 and made some prototypes.
Soldering the QFN packaging by hand is tricky!
Apart from manual soldering, we found some thermal dissipation issues. For this reason, in the new Stepper Driver were implemented 4 layers of copper, ensuring that the temperature was kept within a suitable range.
Below you can see images taken with the thermographic camera which help us greatly in the process:
You can appreciate the decrease in system temperature when doubling the number of copper layers.
With these new drivers the printer performs much smoother movements and the overall sound is considerably reduced. The improvement of the movements implies that the surface quality of the printed parts is considerably improved, eliminating completely visual defects.
To be a bit more technical, the TMC2130 is configured to work with a 1/16 microstepping with 1/256 interpolation. This increase of steps causes the movement to be much smoother than other controllers without affecting the step rate generation of the microcontroller.
This is thanks to the advanced control of the motor windings current.
Finally, it should be said that the drivers have been designed to be mounted in any BCN3D Sigma, allowing all users to benefit from the improvements without having to modify the firmware. On the web you can buy the drivers kit as well as find all the instructions to make the upgrade and start enjoying your new BCN3D Sigma.
Soon we will publish the new designs in the corresponding repositories on Github.