The Cohesion3D LaserBoard uses Trinamic stepper drivers. These have 2 modes: Stealthchop which is completely silent, but not quite as powerful torque-wise, and then Spreadcycle which is more powerful but makes a little noise.
Namely, in Spreadcycle, there might be a hissing sound coming from the motors when they are engaged but standing still (ie: energized/ locked). This is not a fault of the driver, but rather due to a high inductance motor being used on the laser.
We defaulted to use Spreadcycle because this is the most powerful torque wise and makes it possible to move the laser head faster.
To change this to Stealthchop you need to edit the LaserBoard’s SD Card config.txt file.
Have the board powered off when you put the SD Card in/ take it out. Use Sublime Text as your Text Editor.
At the bottom of the config.txt file you will find, at the bottom, a set of switch blocks called spread1, spread2, etc…these correspond to XYZA driver in that order. Flip the logic from true to false. That will put you into Stealthchop and you should have complete silence.
In order to reverse this switch the logic from false to true and you will be back to Spreadcycle mode.