Architecture for Direct Model-to-Part CNC Manufacturing
In the traditional paradigm for Computer Numerical Control (CNC) machining, tool paths are programmed offline from the CNC machine using the Computer-Aided Design (CAD) model of the workpiece. The program is downloaded to the CNC controller and the part is then machined. Since a CAD model does not exist inside the CNC controller, it is unaware of the part to be machined and cannot predict or prevent errors. Not only is this paradigm labor intensive, it can lead to catastrophic damage if there are errors during machining. This paper presents a new concept for CNC machine control whereby a CAD model of the workpiece exists inside the controller and the tool positions are generated in real-time by the controller using the computer’s graphics hardware without human intervention. The new concept was implemented on an experimental lathe machine specifically designed to machine complicated ornamental wood workpieces with a personal computer. An example workpiece was machined and measured using a 3D camera. The measured data was registered to the CAD model to evaluate machining accuracy.
Adaptive ball drop algorithm for toolpath generation of axisymmetric triangulated parts to eliminate overcutting
Computer Numeric Control (CNC) milling lathes are used for pseudo-symmetric ornamental woodworking. A stereolithography (STL) part model is used for gouge-free toolpath generation using methods such as the geometry offset method and the ball drop method. The tool movement between cutter location (CL) points results in gouging of the STL part at convex intersections of triangles (path-gouging). This path-gouging can be controlled to be within user-specified tolerance, with large number of equispaced points in forward and sidestep directions. The resulting toolpath with large number of tool positions considerably slows the machining process. There exists a need for a universal method for efficiently eliminating this gouging and slowdown. In this work, a refined ball drop method is presented that eliminates path-gouging and reduces slowdown by automatically generating a variable step size in the side step and forward directions. To further optimise the number of side steps generated by the presented method, banding is used to reduce machining time while minimising un-machined material and eliminating gouging. The developed algorithm was tested on sample parts and verified by simulation and machining of wooden parts.
Only the Third Heaven?: 2 Corinthians 12.1-10 and Heavenly Ascent
CHAPTER 1 General Introduction PART 1: Texts of Heavenly Ascent CHAPTER 2 Introduction: Heavenly Ascent Texts: A History of Scholarship CHAPTER 3 Jewish Apocalyptic Texts Pre-70 AD CHAPTER 4 Jewish Apocalyptic Texts Post-70 AD. CHAPTER 5 The New Testament CHAPTER 6 Post-Biblical Early Christian Apocalypses CHAPTER 7 The Nag Hammadi Codices CHAPTER 8 The Hekhalot Literature CHAPTER 9 Conclusions to Part One PART 2: 2 Corinthians 12:1-10 and Heavenly Ascent CHAPTER 10 2 Corinthians 12: 1-10 as a Heavenly Ascent CHAPTER 11 2 Corinthians 12.1-10 as a Subversion of the Heavenly Ascent CHAPTER 12 General Conclusions.