Software Setup

Requirements

Setup the TinyG Board

Install FTDI Drivers
Power up and connect the TinyG board using via USB to your computer.
Run the Serial Port JSON Server and leave it running in the background.
Open your browser and go to chilipeppr.com/tinyg
Go to the Serial Port JSON Server fiddle in bottom right and refresh to see the TinyG listed.
Select and connect to the board.
Change the following settings:
- Change Latch Velocity to 50
- X and Y Travel/rev = 36.54
- X and Y Microsteps = 8
- Z Travel/rev = 1.25
- Z microsteps = 4

Workflow

Generate the Geometry

The extrusion path is first created in Rhino. All the measurements are in millimeters unless otherwise specified.
Run the Python Script Editor in Rhino. Use command: EditPythonScript in Rhino Console.
Run this script to generate a G-Code file. The code has been taken and modified from timcastelijn/gcode-generator.
Copy the contents of the saved file that contains the newly written G-Code. Paste it in Chilipeppr to perform the extrusion.

Rhino

Run the Extrusion

This project used browser based Chilipeppr workspace to control the machine.
Open your browser and go to chilipeppr.com/tinyg
Go to the Serial Port JSON Server fiddle in bottom right and refresh to see the TinyG listed.
Select and connect to the board.
Go to ‘Workspace TinyG’ fiddle on top left and click the load GCode button. Paste the contents under ‘Open Gcode From Clipboard’.
Insert the glass rod in the extruder and zero the machine to the correct point for extrusion.
Power on the air-compressor to start the vacuum and ignite the propane torch at low flame. Leave it on for a few seconds till the glass is in semi-liquid state.
Press play button in Chilipeppr GCode fiddle to initiate the movement of the machine.

chilipeppr

Useful Links

# Modified from : https://github.com/timcastelijn/gcode-generator
feedrate= 85   # Carriage Speed | Increment by +- 5
curve_tolerance=0.008
curve_angle_tolerance=5
z_offset = 0
material_mult = 0.01 # Extrusion Speed: A-Axis | Increments of +- 0.001
extruder_axis = 0  # Rotation A-Axis

import rhinoscriptsyntax as rs
import math

pt_prev = [0,0,0]
path = rs.GetObjects("Select Curves/polylines/arcs/circles", rs.filter.curve, True, True)
filename = rs.SaveFileName ("Save", "Toolpath Files (*.nc)|*.nc||", "/users/timcastelijn/documents")

file = open(filename, 'w')

# write header
file.write("G21\n") # Measurement units to mm
file.write("G90\n") # absolute positioning

for curve in path:
    # fast move to path start
    pt = rs.CurveStartPoint(curve)
    file.write("G00 X%0.4f"%pt.X+" Y%0.4f"%pt.Y+" F%0.4f"%feedrate+"\n")

    # detect type of curve for different G-codes
    if (rs.IsPolyline(curve)) or rs.IsLine(curve):
        points = rs.CurvePoints(curve)
        for pt in points:
            dist = rs.Distance(pt_prev,pt)
            pt_prev[0] = pt.X
            pt_prev[1] = pt.Y
            pt_prev[2] = pt.Z
            extruder_axis += dist*material_mult
            file.write("G1 X%0.4f"%pt.X+" Y%0.4f"%pt.Y+" Z%0.4f"%(pt.Z+z_offset)+" A%0.4f"%(extruder_axis)+"\n")

    elif rs.IsArc(curve):
        normal = rs.CurveTangent(curve, 0)
        startpt = rs.CurveStartPoint(curve)
        endpt = rs.CurveEndPoint(curve)
        midpt = rs.ArcCenterPoint(curve)

        x = endpt.X
        y = endpt.Y
        i = -startpt.X + midpt.X
        j = -startpt.Y + midpt.Y

        if ((normal[1] > 0) and (startpt.X > midpt.X)) or ((normal[1] < 0) and (startpt.X < midpt.X) or (normal[1]==0 and (normal[0]==1 or normal[0] ==-1) and startpt.X == midpt.X)):
            file.write("G3 X%0.4f"%x+" Y%0.4f"%y+" I%0.4f"%i+" J%0.4f"%j +"\n")
        else:
            file.write("G2 X%0.4f"%x+" Y%0.4f"%y+" I%0.4f"%i+" J%0.4f"%j +"\n")

    else:
        print "curve detected, subdiv needed"
        polyLine = rs.ConvertCurveToPolyline(curve, curve_angle_tolerance, curve_tolerance)
        points = rs.CurvePoints(polyLine)
        for pt in points:
            file.write("G01 X%0.4f"%pt.X+" Y%0.4f"%pt.Y+" Z%0.4f"%(pt.Z+z_offset)+"\n")
            pt_prev[0] = pt.X
            pt_prev[1] = pt.Y
            pt_prev[2] = pt.Z
            dist = rs.Distance(pt_prev,pt)
        rs.DeleteObjects(polyLine)

file.close()