cnc_machine_goliath

Note: Goliath is no longer at the space. The Laguna is a more capable replacement

Laguna

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 thespace@sktechworks.ca
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 thespace@sktechworks.ca
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

Fusion 360 Toolpaths

I nice formatted tutorial of how to setup a job in Fusion 360 http://evanandkatelyn.com/2018/01/fusion-360-cam-tutorial-for-cnc-beginners/

Fusion 360 Post Processor

Update: the following G28 thing might actually not be necessary. Before setting the origin on the workpiece, move the spindle to a safe location above the workpiece. Then, click “Ref All Home.” If you do this, that location will be the “Home” position that G28 goes to.

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.

Feeds and Speeds Resources

Onsrud has some good charts for chipload of various materials. http://www.onsrud.com/xdoc/feedspeeds

Once you know your chipload range, there are lots of online calculators to help you calculate RPM and feedrate. http://www.monstertool.com/monster_tool_calculators.html