I built a 4 axis cnc for rug tufting using the blackbox x32. I am having an issue trying to figure out how to control the speed of the motor on the tufting gun with is on the toolhead of the machine. Currently, my plan was to use the 0-10v output to set the speed of the gun proportional to the feedrate, but this has an issue. When the toolhead reaches a line with a tight turn, such as the corners of a rounded square, the tool head slows down in order to make the turn and to give the A axis time to turn the gun in the direction of travel (similar to a tangential knife cutter). There is only one speed in the gcode, the feedrate, but this does not always correspond to the actual speed that the toolhead is moving. I found someone on the linuxcnc forums who solved this problem like this: "On my Rugbot I use a Stepgen running in velocity mode, controlled by the Hypot function to control a servo driving a needle to punch rugs It gives me perfectly consistent stitch length regardless of XY direction or speed." Context: Stepgen refers to a software component or module within LinuxCNC that generates step pulses for stepper motors based on commanded movements. Operating in "velocity mode" means that instead of generating steps to move a specific distance, it generates pulses to maintain a certain velocity. Using Stepgen in velocity mode allows for the adjustment of the motor's speed in real-time based on the actual movement speed of the machine. This ensures that the tufting motor's speed is directly correlated with the machine's speed, achieving consistent stitch density. The Hypot function is a mathematical function that calculates the length of the hypotenuse of a right-angled triangle given the lengths of the other two sides. In the context of CNC and motion control, it's used to calculate the actual movement speed of the machine's head by considering both the X and Y directional speeds. This calculation effectively gives you the "straight-line" speed of the head at any point in its movement. How can I do this on the Blackbox X32?
You **may** be able to use the LASER mode with dynamic power (M4) to produce a drive signal proportional to travel speed. (Just an avenue to explore, rather than saying that it will work). grbl/doc/markdown/laser_mode.md at master ยท gnea/grbl (Although note that the firmware inside the BBX32 is grblHAL rather than grbl - it is backward compatible and may offer more options that I don't know about if you do some digging.)
