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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
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