Intro to the CNC Router

Transcription

1 Intro to the CNC Router

2 Objectives Upon completion of this course you will be familiar with: a) the safety precautions for using the CNC router b) the terminology of CNC machining (CAD, CAM, postprocessing) c) taking a project from design to machine ready (GWizard, VCarve) d) the setup and running of a project (Mach 3) To complete the certification process, you will need to arrange for a CNC machinist Tiffany Bell-Horwath, Elly Hall, Mike Horwath, Jon Neal, Coy Paeltz, Loren Parker to observe you running a project in addition to the one being done today.

3 Outline 0.) History 1.) Safety 2.) Overview of the CNC Router 3.) Overview of CNC Machining 4.) VCarve 5.) Running a Project

4 History NC (Numerical Control) was developed in the late 1940s and early 50s by John T. Parsons in collaboration with MIT to help in the post WWII manufacturing effort. Aircraft parts were becoming more complex and required a level of precision that human operators could not achieve. At first machines were hardwired, but, by 1952, instructions were being entered via external media - punched tape. Five years later, NC machines were being installed in metal working production environments all over the United States. By the mid 1960s, NC technology was playing a dominant role in the industry. Punched paper or aluminium tape predominated until about 1980, when the growth of microprocessor technology made it possible for computers to be connected directly to NC machines, and CNC was born. after Alain Albert FPInnovations Forintek Division UnderstandingCNCRouters.pdf

5 Safety Protect Yourself Protect Your Colleagues Protect the Machine

6 Protect Yourself (after B. Walsh) Hair tied back. Safety glasses. Ear plugs or covers. No lanyards/hoodie ties. No hand jewelry (rings, watches). No gloves. No long sleeves (or roll them up). Close-toed shoes (wood chips can hurt!). Vitruvian Workman by Joseph Sikorski 2014 The idea is to not have anything catch on the spinning tool and pull you into the cutter.

7 Protect Your Colleagues Secure the mill. Secure your material. If you re cutting wood, be sure there are no cracks or loose knots in the material.

8 Protect the Machine Secure the mill. Secure the material. Clear the spoil board of any tools & old nails, etc. Don t cut the hold-downs (nails, screws, clamps). Don t gouge the spoil board. Don t leave the machine while it s running.

9 Machining can be additive formative or subtractive.

10 Machining can be 2D 2.5D (The Z axis only puts the cutter at depth.) or 3D with smooth curves in XZ & YZ planes. The CNC router is subtractive, and can machine 2D, 2.5D or 3D parts.

11 CNC (Computer Numerical Control) machining has 3 stages. CAD (Computer Aided Design) Draw up your part in Fusion 360, Illustrator, SketchUp, VCarve etc. CAM (Computer Aided Manufacturing) Decide what mills (cutters) to use and what toolpaths (design features) to cut. Postprocessing Produce a text file ( GCode ) which tells the CNC machine where to go and how fast to get there.

12 The Hive made CNC router. Table Spoil board takes up to a 5 X x 8 Y workpiece E-cord X-Zero Limit LED Gantry Router assembly ~5.5 Z range; sided milling sided milling

13 Router Assembly Router Dust Collector Hose Blast Gate Dust Shroud

14 Spindle Collet Nut Mill Z Zero Probe

15 Mills Mills (called bits in woodworking) are the cutters used in CNC routers. Mills cut toolpaths as directed by GCode. A toolpath tells the gantry where to put the end of the mill in X, Y, Z space, one point at a time. To follow the toolpath, the gantry moves from point to point at a rate specified as a feed (GCode F ). To cut (with its flutes) along the toolpath, the mill spins at a specified rate: this is the speed (GCode S ). This info on spec sheets is often referenced as feeds & speeds. When moving (& not cutting) between toolpaths, the mill may travel at the maximum machine speed. This movement is called a rapid.

16 Mills are described by the diameter of the stem, the number of flutes (cutting edges), the geometry of the cutting end, cutting length (the length of the flutes), and the material: HSS (high speed steel) or solid carbide. The material cannot be guessed by appearance, only the label on the box. cutting length 0.5 fishtail shape max. stickout flutes When calculating feeds & speeds, you need to know how far the mill extends beyond the collet. This ranges from the cutting length to 1/2 the mill length. This is stickout.

17 Diameters can range from a millimeter or 1/16 to > 3/4. Stickout can range from 1/8 to >1 1/2. Geometry Bits are usually HSS with carbide cutters welded on. Carbide cutter Endmill (Fishtail) Corner Radius (Bull Nose) Ball Nose V bit (yes, bit )

18 Number of Flutes Can Range from 1 to 11 or more!

19 Flutes have their own geometry. Up Cutting (Right hand) Down Cutting (Left Hand) Compression

20 Mills are not Drills Mills are intended, and designed, to cut horizontally, not vertically. If you need to plunge, use a drill! (Yes, a 1/4 drill will work in a 1/4 collet.)

21 To get going with your projects, you will need a Starting Mill Set Do not use the metal shop mills! The lubricant will ruin the spoil board and your project! 0.25 fish tail or bull nose end mills x 2 (two because breakage) good for pockets & profile cuts 0.25 diameter shaft V bit (mill or router bit) good for engraving letters, outlines, etc. optional 0.25 ball nose good for curved surfaces (3D models)

22 How do we figure out feeds & speeds? Check the source from which you got your mills. Check for generic charts online. Check with the Hive 1 3 copy of GWizard. GWizard, a very brief overview.

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24 Finally, Installing a Mill The collet is a compressible washer that holds the mill in place. Place the collet squarely into the collet nut. It should snap easily and squarely into place. The collet

25 Press the mill into the collet from below. Finger tighten the collet nut fully. Finger tighten the nut & collet onto the spindle End of flute 1/16 outside of collet nut.

26 Hold the wrenches close to the collet nut and tighten the nut about (<) 1/4 turn. If you encounter resistance when placing the nut, ask for help, don t force the nut! $tripping the threads means a new $pindle!

27 Summary Safety: Protect your eyes, ears and fingers. Protect your colleagues. Protect the machine. Argot: The CNC router does subtractive machining. It can produce 2D, 2.5D and 3D projects. Mills are identified by diameter, number of flutes, cutting length, geometry, and material. Mills cut toolpaths at a defined feed rate and speed of rotation. Mills move between toolpaths at a feed rate called a rapid.

28 References CAD/CAM/postprocessing VCarve vectric.com - downloads, FAQs, tutorials Fusion360 autodesk.com/products/fusion-360/overview (if generating GCode in Fusion, de-select G28) GWizard CNCCookbook cnccookbook.com/gwizardgwizardinstall1sc.html also a lot of info on all aspects of CNC milling GCode Tormach more complete descriptions of GCode words (commands) like the S word for speed and the F word for feed rate.