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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
Materials recommended for CNC
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
Materials not recommended for CNC
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