CNC Mill Tutorial
Step 1: Machine Setup
Before you start cutting, you’ll need to attach your material to the Othermill’s machining bed. This is called “fixturing,” or “work-holding.”
Double-sided tape works great with flat, thin material like circuit boards and thin metal or plastic pieces. If the tape isn’t enough, a bead of hot glue around the edges of larger or rougher materials, like wood, plastic, and machining wax, works great. The machining bed is also equipped with tiny T-slots that can be used for fixturing with bolts and T-nuts.
The Othermill cuts most anything softer than steel, but metals and other hard materials like aluminum or brass may still generate a lot of heat as they are machined, which can ruin or break tools. You can use any cutting tool with a 1/8″ shank, but remember: the smaller the tool, the more fragile it will be, and the slower and shallower you’ll need to plan your cutting speed and depth of cut. Big tools are great for roughing passes and clearing out lots of material.
For real cuts, load your material only after the machine is oriented!
Loading a tool
The machine can cut with many tools. Changing tools is accomplished by using a tool holder to tighten a slitted collet around the smooth shank of your tool (usually an end mill or drill).
At the Makerspace- tools are located on top of the machines, and materials can be purchased from out vending machine located on the first floor of the Watt Family Innovation Center.
To access and use the OtherMill in the Invention Lab, speak to a staff member.
Remove the collet and the two wrenches from the Accessory Kit. Remove the collet nut from the bottom of the tool holder by using the smaller wrench on the flat part of the tool holder to secure it in place while loosening the nut with the larger wrench.
Insert the collet into in the collet nut, until it pops into place. It may still be a little bit wiggly.
With the collet in place, thread the collet nut back onto the tool holder by hand.
Tighten by two or three turns, holding the tool holder in place with the small wrench if necessary. Do not fully tighten the nut without a tool.
Connecting to the Othermill
Connect the power supply to the power jack on the back of the Othermill with the built-in cable. Connect the power cable to the power supply and plug it into a grounded electrical outlet.
Plug in the USB cable to the USB jack on the back of the Othermill. Connect the other end to your computer.
With the safety windows in place, turn on the Othermill by twisting the red emergency stop button clockwise and pushing the power button on the back of the machine. The interior lights will turn on and the Othermill will beep.
IMPORTANT: The power cable has a locking connector. To remove the cable, always pull by the connector. Do not pull by the cable.
From here on out, the process will be driven entirely through your computer with Othermill’s control software, Otherplan.
Step 2: Computer Setup
You’ll need to install Otherplan on your computer to operate the Othermill. Otherplan is available for Mac OS X 10.8 and above.
Once the download completes, open the .dmg file and drag the Otherplan application to your Applications folder. Open Otherplan by double clicking the application icon.
With Otherplan open on your computer, the first thing will be to validate that the firmware is up to date. If the firmware on your Othermill needs to be updated, Otherplan will guide you through the process.
When prompted, home (calibrate) the Othermill by clicking the Start Homing button.
If you are starting your mill for the first time, Otherplan will also have you locate the spoilboard. The Locate Spoilboard dialog box will automatically pop up, and give you prompts to help the machine locate the spoilboard correctly. The spoilboard is a sacrificial piece of material that can be machined while you are making a part, and replaced occasionally to create a fresh, flat surface.
Step 3: Orienting the Machine
When you’re actually making a cut, you’ll want to orient the machine before loading your final tool or materials in place, since the locating sequences require a special tool and bracket to work properly.
The machine will have highly precise instructions for where to move to cut your part, but it doesn’t yet know how big your material is, or exactly where it is located. Neither does it know how long your tool is - every time you load a tool, it will be held at a slightly different length. The details are critical.
There are detailed guides provided by Othermill for Bracket Locating (orienting the machine to your material) and Tool Locating (showing it how long the tool is). Rest assured that these details will become second nature over time.
You will launch bracket locating by clicking on “Setup Fixturing…” in the “setup” panel of Otherplan. This will start a process to locate your material, moving the bed into the loading position so you can load in the Othermill bracket onto an otherwise clear spoilerboard.
The bracket usually gets bolted to the front corner of the bed, but you will put it where you want your part to be. Place it in the right spot, and then snug the bolts - don’t go crazy tight.
With the bracket attached, you’ll use a probe - either a special ⅛” tool or a normal end mill loaded upside-down with the ⅛” shank sticking out - to be the eyes of the machine. Then, you must move the tool into the “safe zone” of the machine, and after ensuring the area inside the machine is totally clear, you can start an automatic program that will use the known tool (⅛” probe) to test points to determine the exact location of the bracket.
Remember, the bracket needs to be tested every time it is installed. And once you start the probing process, the machine will be running on its own! Remain alert.
Once you have your desired cutting tool (end mill, drill, etc) loaded securely in a tool holder inside the machine, you will launch tool locating by clicking on “Set…” or “Change” in the tool section of the “setup” panel. This will start a process to measure your cutting tool. You will choose “Change” if it thinks the program thinks it using another tool than it actually has loaded, and “Set…” if there is not a tool currently recorded in the computer.
It is critical to make sure that the tool in the Othermill matches the tool in Otherplan, and that there is a clear surface below the tool without any chips, tape or other debris to affect the measurement.
For most tools, Automatic Locating will be appropriate. Auto locating runs a program to touch the tip of the tool to the table below it, sensing contact through electrical current and then referencing the spindle height to determine the length of the tool. For certain tools, Manual Locating will be necessary. This requires the user to move the tool just to the surface of the table to set the height. Always trust what you see in the Othermill over what’s shown in Otherplan.
After setting the tool length, the machine will re-home itself to ensure correct alignment.
Step 4: Getting Ready to Cut
The process outlined below what is called a “toolpath,” which is a series of coded instructions for the machine to know where to move in order to create your part(s). This is called a computer aided machining (CAM) program.
In Otherplan, click "Import Files" and select the your design file.
You'll see a rendered version of the file appear on the machining bed in Otherplan, and the file name should appear on the right side of the screen with some options and buttons below.
Click the "Setup Material" button and choose "Single Sided FR-1." Size "Standard" should be pre-selected.
Click Continue to "Set Material Properties." Leave all the default values as they are, and click "Done."
On the right side of the screen, under YourFile.name, there are selections for the Traces, Holes, and Outline.
Click these buttons and notice how the rendering in Otherplan changes to show what parts of the file will be cut into the FR-1 board. Make sure all three buttons are selected so you are cutting all three types.
Right below this, there is a place to choose which tool you'll be cutting the board with. Select a the end mill (this should already be selected by default).
Becoming familiar with the Otherplan interface will take time - you can practice on your own before class, in order to get a feel for what works and what doesn’t, and to prepare good questions to help you move a project forward.
Step 5: Milling
So, whenever you use the Othermill, you will need all of the following:
A design file in Otherplan the Othermill needs to know what to cut!
The machine needs to properly locate the bracket, in such a way that it matches your origin in your design file. This is necessary to properly orient the machine to the workpiece inside of it.
Your tool and material must be properly secured in place.
Your machine must know how long your tool is.
Once you have your design ready, you need to convert it into a file for the CNC controller to read, in order to create a toolpath for milling your part. Otherplan imports SVG, BRD, Gerbers, and G-Code.
Clean up afterwards. Be careful of hot material.
Once all this is done, you’ll be ready to mill!
Click the “Start cutting” button and remain attentive for the whole duration of the cut. Never leave the machine running unattended. When the cut is finished, you can scrape up your parts with a putty knife, if you used double stick tape. Clean up all your tools from the machine, and leave it cleaner than you found it.
As with any power tool, do not use the Othermill if you are tired, distracted, or otherwise impaired.
This can include being frantic and stressed, talking or texting on a cell phone, or impaired by drugs or alcohol.
Do not operate the Othermill with damaged or dull bits.
Use the Othermill’s Emergency Stop button to immediately stop the machine when necessary.
Do not leave the Othermill unattended while in use.
Prior to operation, make sure the collet and tool are secure, and remove the wrenches and other tools from inside the Othermill.
Do not use the Othermill if its safety windows are cracked.
Do not touch the sharp ends of bits, even when the Othermill is not in operation, as they may cause injury.
Do not touch or place hands near moving parts — such as the carriages, rails, frame, spindle, and pulleys — while the Othermill is in operation.
When using the Othermill, tie back long hair and avoid clothing or jewelry that may get caught.
Do not touch moving parts after use. They may be hot.
Ensure that the Othermill is clear of debris before and after operation. Use a brush to clean metal debris, as vacuum-cleaning metal shavings could cause a fire in the vacuum cleaner.