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CNC Training

Safety and Basic info
  • Always have protection
  • Eyes
  • Ears
  • Loose clothing should not be worn
  • Hair tied back and out of the way
  • If you notice anything strange with the machine DO NOT USE IT
    • Notify Albert
  • Be aware of where the big red button is
    • Pushing the button will stop the current job from processing
    • It will not stop the router
    • turn off the switch for that
    • turn off the switch for cnc power
    • notify Albert
  • Be aware of all the different ways you can shut off the machine
    • Safety should be your number one concern
    • You can always fix or redo a CNC job
    • Fixing a broken face is harder
wood
  • hardwood
  • softwood
  • composites - MDF, OBS, etc
plastics
  • Be aware that plastics will melt if feeds and speeds are not set correctly
  • Polycarbonate
  • ABS
  • Acrylic
  • HDPE, UHMW
  • etc
Phenolics
  • G10, FR4, Garolite
Metal of any sort

* In theory the large CNC has the capability but it is not recommended * Please use the Sherline for small metal parts * Anything larger contact an external machine shop

Make sure your work material is secured

  • This ensures your safety and those around you
  • Material that is not properly secured to the work surface has the potential to be ejected by the machine and injure anyone in the vicinity

File Formats

  • Recommended file format from vector software is DXF
  • Depending on the CAM software it may be able to accept other formats
  • CAM software and GCODE conversion
  • SK Techworks has an art license for MeshCAM
  • Aspire is installed on the computer at Techworks
  • There are many other paid and free solutions out there
  • We will be going over Aspire

Aspire

  • Aspire is CNC CAD/CAM package that has the ability to generate GCODE output for 3D carving and 2D profiling
  • Aspire can accept multiple vector file formats including STL, DXF, OBJ and others
  • The workflow for Aspire can be separated into two parts:
    • Importing/creating the vectors and setting up the toolpaths
    • Importing/creating Vectors
  • When you start up Aspire you can either start a new job or open an existing one
    • in our case we want to start a new file
  • you will be greeted with a screen asking for the dimensions and type of material
  • there is also a section asking what the zero position is for the machine
  • select the top of the material for z-axis zero
  • I also recommend using the center point of drawing for x-y zero as it is simpler for lining up a job on your work piece - more explained later
  • Please note the the long axis on our CNC is the x-axis
  • If you have already generated your vector output you can just import the file by going to File→Import→Import Vectors
  • This is the workflow for 2d profiling
  • If there is an interest in 3D Carving I can go over this at a later date
  • After you have imported your vectors you then need to ensure that the vectors are closed
    • vectors that are not closed will result in unexpected toolpaths when we try to generate them
  • Once you have fixed your vectors you can then resize and position them as you like on the material
Creating Toolpaths
  • Once you have your vectors in place it is not time to create the toolpaths
  • This is how the CAM software will generate the GCODE for the CNC machine to run
  • On the top right of the program there will be a tab that contains all the controls for creating toolpaths
  • The operations we are interested in for 2D profiling are:
    • profiling
    • drilling
    • pocketing
Profiling
  • This operation will cut out the shape of the vector you want
  • in the case of a circle let us say a generated toolpath will cut either on the inside, outside, or on the desired vector depending on the effect you require
  • It is important that the vector is closed when trying to do inside and outside profiling. An unclosed vector will net an unexpected toolpath
Drilling
  • This is pretty self explanatory
  • One thing to note is this operation will only work on properly generated circles
  • some vector softwares will output a circle as a series of lines
    • while the end result resembles a circle it does not contain the same information
    • mainly where the circle is located
    • the problem here is that if you were to try to generate a toolpath on such a circle, Aspire will ignore it as there is no centerpoint to locate and drill
Pocketing
  • This operation will clear the area enclosed in a vector
  • for example if you have a circle and you do a pocket operation on it you can make a bowl or cup.
  • again it is important to ensure your vector is close so that the generated toolpath comes out as expected
Feeds and speeds, endmills
  • When generating GCODE with the CAM software, it takes into account the physical start point, endmill properties, feedrate, and speed
  • The physical starting point should already be set when you defined your workpiece properties. If anything has changed you can access them through the edit menu
  • endmill properties are accessed when you have chosen a toolpath operation to perform
  • once you have selected a toolpath you then need to select the tool you wish to perform the cut
  • If a tool is not available in the default list you can create a new one to suit your needs
  • At the point you are accessing the endmill properties you can also change the feedrate and speeds
    • feedrate refers to the rate at which the endmill travels while cutting. I believe the default is inch per minute (IPM) for the large CNC.
    • Speed refers to the spindle speed measured in revolutions per minute (RPM)
    • Feeds and speeds are a very important factor in the success of your job.
  • correctly set feedrate and speed will yield great finish and longer tool life
    • as a rule of thumb the plunge rate should be set to ½ your feed rate
    • pass height - which is the distance your endmill plunges into the material to perform a cut- should be a maximum of ½ the tool diameter
  • The CNC is capable of doing 100 IPM rapid movements but doesn’t like cutting at that speed depending on the material
    • 50 IPM is a good starting point for wood
  • Mach3 has the ability to dynamically change the feedrate during a job so you can start a job slow, then speed it up as you get to know the material properties
  • as the spindle is technically a tile router, it is not controlled by the CNC software. So speed is manually set with the dial.
  • setting the speed too fast and feedrate slow will result in burning or melting
  • setting the speed to slow and feedrate fast will result in breaking

Mach3 software

  • How to load GCODE
  • Keyboard Operations
    • Jogging the axes
      • the arrow keys control the x and y
      • pgup and pgdn control the z
    • rapid
      • shift
    • fine tuning
      • ctrl
  • emergency stop
    • big red button
    • esc key
  • setting feeds and speeds
  • Run the Job

Basic operations

  • Power to the machine
  • power to the router
  • big red button
  • fan power for gecko
  • Tool Changing
  • Securing material
  • zeroing the machine
  • clean chips
  • Leave the machine in a state where someone else can use it with minimal setup
    • don’t leave your chips for someone to clean up
    • don’t leave your endmills in the router
    • don’t leave scrap material or custom sacrificial board on the machine
    • scrap material goes in the bin
    • if the bin is full, fucking empty it
      • we pay monthly for loraas even if we don’t use it
      • so we might as well use it
Fusion 360 Toolpaths

This is very, very preliminary, but critical: DISABLE G28. If you leave G28 enabled, the machine will rapid to a bad place. If you are lucky, it will only break your bit. If you are not lucky, you will break the machine. This has already happened once.

DISABLE M6. I'm not sure if this actually causes problems, but we don't have a toolchanger, so telling the machine to pick up a tool is pointless.

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