AbstractRapid prototyping is widely used to reduce time to market in product design and development. Today’s systems are used by engineers to better understand and communicate their product designs as well as to make rapid tooling to manufacture those products. Computer Numerically Controlled (CNC) milling machines are part of this technology. This project will present the design of a small CNC machine, and production, and analysis of a small CNC machine. This machine has the characteristics demanded by the industrial and academic designers. Studying the existing machines aided in setting specifications for the new design. Comparing the performance of the new machine with existing machines will improve future designs.
Table of Contents1 Chapter 1 – Introduction & Problem Solution 1

1.1 Solution Methodology 2

2 Chapter 2 – Performance Metrics of Numerically Controlled Machines 4

1 2.1 Geometrical Errors 42.1.1 Backlash 92.1.2 Scaling Mismatch 102.1.3 Squareness Error 122.1.4 Cyclic Error 132.1.5 Lateral Play 152.1.6 Reversal Spikes 161 2.1.7 Stick Slip 182.1.8 Vibration 192.1.9 Master-Slave Changeover 202.1.10 Straightness 222.1.11 ASME Standard Test Method 23

3 Chapter 3 – Performance Evaluation of Existing Machine 25

3.1 Discussion o f Measurements of Microkinetics Performance 263.2 Discussion o f Measurements of Prolight Performance 31

4 Chapter 4 – Design Specifications for the New Machine 365 Chapter 5 – Design of the New Machine 39

5.1 The Hardware 405.1.1 The Structure 405.1.2 X & Y Axis 415.1.2.1 Axis Motor 435.1.2.2 Axis Actuator Hardware 455.1.2.3 Rolling Contact Bearing 485.1.2.4 Motor Mounting 545.1.2.5 Linear Slides 565.1.3 Z Axis 615.2 The Software5.3 Driver and Electronics

6 Chapter 6 – Measurement of Performance of the New Mill7 Chapter 7 – Discussion of Results8 Chapter 8 – Recommendation for Future Work AppendicesA. G & M CodesB. Calculation Sheet for the Ball ScrewC. Important PartsofEMC.INI FileD. Diagram ofThe Driver’s CircuitE.  Calculation and Selection o f the Stepper MotorF. Engineering Drawings of GVSU MillReferencesTable of FiguresFigure 2.1.1 the hardware required for the Renishaw ballbar test. 5Figure 2.1.2 feed in, out, angular overshoot arcs and the data capture arcs. 6Figure 2.1.3 the data capture range of the ballhar transducer is approximately 2mm. 7Figure 2.1.4 a plot o f time vs. transducer travel shows the period of machineacceleration and how it would affect the integrity o f the data collected. 7Figure 2.1.1.1 an example of positive backlash. 9Figure 2.1.1.2 the interpolation of the inward step in the ball bar plot. 10Figure 2.1.2.1 an example of a scaling mismatch error. 11Figure 2.1.3.1 positive and negative squareness. 13Figure 2.1.4.1 an example of cyclic error. 14Figure 2.1.5.1 an example of a lateral play in the y axis. 15Figure 2.1.6.1 an example plot of a reversal spikes error. 16Figure 2.1.6.2 an example o f the effect of a reversal spikes error on the actual circle milled on the part. 17Figure 2.1.7.1 stick-slip error as shown on a diagnostic problem. 18Figure 2.1.7.2 the effect of stick-slip on the machined part. 19Figure 2.1.8.1 a typical plot showing vibration error. 20Figure 2.1.9.1 a master-slave changeover error as captured by the ball bar diagnostic plot.  21Figure 2.1.9.2 master slave changeover every 45″. 21Figure 2.1.10.1 three distinct distortions in the plot caused by an error in the y axis straightness. 22Figure 3.1.1 a plot of the ballbar test on the Microkinetics CNC express. 27Figure 3.1.2 representation of the angular error and how it can cause a scaling mismatch error. 29Figure 3.2.0 diagnostic plot of the proLIGHT on the same scale as the Microkinetics. 32Figure 3.2.1 a plot of the ballbar test on the proLIGHT CNC machining center. 32Figure 3.2.2 duplex arrangement angular contact bearings. 34Figure 5 a solid model of GVSU mill. 39Figure 5.1.1.1 the structure of GVSU mill. 40Figure 5.1.2.1 the X, y axis including the linear slides. 41Figure 5.1.2.1 the axis drive system. 42Figure 5.1.2.2.1 lead screw and nut. 45Figure 5.1.2.2.2 ball screw and nut. 46Figure 5.1.2.3.1 deep groove ball bearing. 48Figure 5.1.2.3.2 the driver and the follower pulley diameters and distance. 51Figure 5.1.2.4.1 timing belt, and timing pulleys. 54Figure 5.1.2.5.1 illustration of the dovetail slides. 56Figure 5.1.2.5.2 illustration of the linear ball bearing slides. 57Figure 5.1.2.5.3 illustration of the crossed roller bearing slides. 58Figure 5.1.2.5.4 the guided linear sliding system. 59Figure 5.1.3.1 the spindle assembly. 61Figure 5.3.1 the drive rack and the G201A inside. 66Figure 6.1 the first diagnostic plot of the new machine using a 50 mm ballbar. 69Figure 6.2-1 diagnostic plot of the second test on a 100 pm plot scale as the first test.72Figure 6.2-2 diagnostic plot of the second test on a 50 pm plot scale. 72Figure 6.3 diagnostic plot of the final test. 74Figure 7.1 percent deviation from the compromised performance values. 79Figure 8.1 self aligning linear bearing may cause unwanted movement of the axis 82List of Symbols and AbbreviationsCNC Computer Numerical Controlmm millimeterm meterpm micro meter 9 theta, the value quoted for squareness by the diagnostic softwareDy the wavelength of the cyclic sinusoidal errorASME American Society of Mechanical EngineersCW ClockwiseCCW Counter-ClockwiseISO International Organization for StandardizationJIS Japanese Industrial Standardoz.in. ounce per inchRPM Revolution Per MinuteVAC Volts of Alternating CurrentIbf pounds of forcelb pounds of weightDeg. degreeCMM Coordinate Measuring MachineDC Direct CurrentFa axial forceL lead of a ball screw (inches)T torquee efficiencyn pi(p belt inclination angleC distance between centers of pulleysRi radius of the motor pulleyRi radius of the screw pulley rad radiansF  B m a x the maximum radial forcea angle of warp of smaller pulleycoefficient of friction between pulleyHP Horse PowerAFBMA Anti Friction Bearing Manufacturers AssociationP equivalent loadFr applied constant radial loadV rotation factorX radial factorY thrust factorL fatigue life expressed in millions of revolutionsC the basic dynamic load ratingNC Numerical ControlCAD Computer Aided DesignCAM Computer Aided ManufacturingDOS Disk Operating SystemPCI Peripheral Component InterconnectEMC Enhanced Machine ControllerAPI Application Programming InterfaceNIST National Institute of Standards and TechnologyGUI Graphical User InterfaceMDI Machine Device InterfacePC Personal ComputerTIL Transistor – Transistor Logic