SCARA Arm Sand Table

jeffeb3 · January 25, 2022, 4:59am

That’s really neat.

But the math in sandify and the previous SCARA machines did not have that 1/3. This is the code I am using to convert from a regular theta rho position to a SCARA position:

github.com

jeffeb3/sandify/blob/5a6011b1051e55580e002ddfc3656603411703df/src/common/geometry.js#L216


      
          
              previousRawTheta = rawTheta
              previousTheta = theta
              vertices.push(new Victor(theta, rho))
            }
          
            return vertices
          }
          
          // Convert theta, rho vertices to goofy x, y, which really represent scara angles.
          export const toScaraGcode = (vertices, unitsPerCircle) => {
            return vertices.map( thetaRho => {
              const theta = thetaRho.x
              const rho = thetaRho.y
              const m1 = theta + Math.acos(rho)
              const m2 = theta - Math.acos(rho)
              const x = unitsPerCircle * m1 / (2*Math.PI)
              const y = unitsPerCircle * m2 / (2*Math.PI)
              return new Victor(x,y)
            })
          }

This whole thing started because I wrote a python script you could run in a web interpreter that would read in the thetarho output and generate the gcode. If we need to play with a 1/3 value, then I think that is where we should do it.

This is that post with the script. It needs to run next to the thr file and it will make a gcode file. I don’t know how much coding you know, so I am starting here.