G CODE THE SHERLINE MILL Michael Stephens 2007 Table of Contents I Purpose p4 II Background p4 III Overview of the Sherline Mill p4 IV Setting Up the Sherline Mill p4 V Sherline Mill Accessories p5 A End Mills p5 B End Mill Holders p5 C Flycutter p6 D Milling Collet Set p6 E Mill Tooling Plate p6 F Mill Vise p6 G Step Block Hold down Set p6 VI Orientation of the Sherline Mill p7 VII Limits of the Sherline Mill p7 VIII Centering the Sherline Mill p8 A Manually p8 B Using a Test Program p9 IX Operating the Sherline Mill Manually p9 X Operating the Sherline Mill Using the Sherline CNC Inch v4 51 Program p10 XI Operating the Sherline Mill Using the Sherline CNC Metric v4 51 Program p10 A Starting the Program p10 B Program Basics p11 C Different Screen Information p12 D Operating In Manual Mode p13 E Operating In Automatic Mode p15 2 XII Overview of G Code p16 A Syntax p16 B Tables p17 C Example G Code p17 1 A Basic Circle Program p17 2 A Circle Program with Offsets p19 3 Rectangular Box with Cutter Compensation p20 4 Pulley Program p21 D Other Useful G Codes p22 XIII G Code Writing Suggestions p25 XIV Suggestions for Locking Down a Part p28 XV Feedrate vs Cutting Rate p28 XVI Other Resources p29 APENDIX A G M Code Reference Tables p30 APENDIX B Sherline Accessories Shop Guide For the Mechatronics Lab p33 A CNC Mill Z axis Backlash Lock P N 4017Z p34 B SHERLINE End Mill Holders p37 C SHERLINE Flycutter p39 D SHERLINE Milling Collet Set p41 E SHERLINE Mill Tooling Plate p42 F SHERLINE Mill Vise p44 G Sherline Step Block Hold down Set p47 3 I Purpose The purpose of this document is to serve as an introductory explanation of how G Code functions The aim is that those reading this will be able to learn the basis of G Code and more specifically G Code writing for the Sherline CNC Mill in use by the Mechatronics Lab GE 423 at the University of Illinois at Urbana Champaign II Background G Code is the programming language supported by a variety of CNC Mill Machines While it is standard in theory many different manufacturers and different milling machines will adapt G Code to serve their desired functionality The G Code discussed in this overview is compatible with the Sherline Mill III Overview of the Sherline Mill In principle the Sherline Mill is has the physical ability to move freely on four axes X Y Z and A However the model in use by the Mechatronics Lab is restricted to the X Y and Z axes Control of each axis can be accomplished in one of three ways 1 Manually If the Power Switch to the Mill is in the off position then the crank wheel on each axis can be moved freely 2 By the Sherline CNC Inch v4 51 If the Power Switch to the Mill is in the on position then you can use this program to operate the X Y Z and A axes Once turned on the control of the axis is done by motors and the mill operator will not be able to turn the crank wheel s manually 3 By the Sherline CNC Metric v4 51 If the Power Switch to the Mill is in the on position then you can use this program to operate the X Y Z and A axes Once turned on the control of the axis is done by motors and the mill operator will not be able to turn the crank wheel s manually The Power switch for the Sherline Mill is located on the left side of the CPU Shell It is a DPST switch When the switch is in the up position a red LED and the Sherline Mill turn on Once again even though the program can control a fourth A axis there is no motor control for one on the current Sherline Mill The Sherline Mill model in the Mechatronics lab is marked with metric units This is not to say that you cannot use the second choice above but the first of third options are preferred when working with the mill IV Setting Up the Sherline Mill There are several basic steps that need to be accounted for prior to turning on the mill 1 It is important that the mill is properly secured and free of obstacles Check to ensure that the mill is bolted down to a level surface and is able to move without restriction in its entire range of axes movement 2 It is important that the axes control cords are connected Check to ensure that X Y and Z axes cords are connected from the CPU to each axis appropriately 4 There should be one cord that is left hanging the A axis control cord from the CPU 3 It is important that the Z axis is unlocked before moving it by hand or with a program The lock for the Z axis can be found on the threaded screw for the Z axis movement To check to see if the Z axis is locked try to move the Z axis crank wheel before turning the power on If the crank wheel turns freely then the Z axis is unlocked To lock or unlock the Z axis Please see Figure 1 for reference of part names 1 Loosen the Flat Point Thumbscrew 2 Move the Adjusting Arm to the desired position i Locking Move the Adjusting Arm as far left as possible so that the Brass Locking Lever is as far left as possible ii Unlocking Move the Adjusting Arm as far right as possible so that the Brass Locking Lever is as far right as it will go as seen in Figures 1 and 2 3 Tighten Down the Flat Point Thumbscrew Figure 1 Figure 2 For more information on the locking mechanism for the Z axis please see CNC Mill Zaxis Backlash Lock P N 4017Z on p34 V Sherline Mill Accessories A End Mills End Mills consist of a double sided cutting tool used to cut through material on a mill or lathe They come in a variety of different sizes The smaller sizes can be help by a milling collet while the larger sizes need to be held by a End Mill Holder B End Mill Holders End Mills Holders are used to hold End Mills of 3 8 size or larger in diameter The End Mills are held in place with a set screw that goes into the flat ground on the shanks of the End Mills When setting an End Mill tighten the screw to the point where the End Mill is held but it is not tight Then press the End Mill up as far as possible and tighten For more information please see the SHERLINE End Mill Holders P N 3079 page 37 5 C Flycutter The Flycutter is intended to help machine flat surfaces The cutter is essentially a lefthanded lathe tool It is important when working with …