Introduction: Engraved Silhouette Pendant
Here are Other Machine Co., we're having fun experimenting with cutting a variety of materials on the Othermill. We're recording our machine settings and making notes on what works and what doesn't so we can incorporate them into our software and make using the Othermill a lovely experience for the new user. The advantage for you is that every time we figure out how to do things just right, you get a fun project tutorial.
This particular piece is a Victorian-style silhouette cutout of a small friend of OMC, with her name engraved beneath it. (Yes, Emma Danger is her real name.)
Step 1: Tools and Materials
- Double-sided tape or hot glue
Blank jewelry bezel available at craft and hobby stores. A bezel is the actual pocket that holds material in a piece of jewelry. Here, we're cutting designs into the bezel to make a pendant.
G-code for your design We've included the files we used for this design, if you'd like to use them.
Step 2: Wait. Back Up. G-Code?
In the previous step, we mentioned you would need a "G-code" file.
G-code is the programming language that the Othermill (and most other CNC machines) needs to run. Generating G-code is not as scary as it might sound. It just involves learning a little bit about CAD (computer-aided design), CAM (computer-aided machining), and how they help turn your ideas into code that your machine will be able to understand.
CAD programs, such as FreeCAD, SketchUp, Rhino, and SolidWorks, allow you to work with pre-existing project designs or create designs of your own. They can show you 2D or 3D models of your project and allow you to see it as it might appear once you make it into a physical object.
CAM software, such as MeshCAM, VCarve, Cut3D, and FreeMill, takes the file you created in CAD and translates it to G-code, which tells your CNC machine exactly how to carve out the material to make your object. Think of G-code as a super-precise recipe for your machine to follow, including the tools you'll be using, how big the workpiece is, how fast your spindle turns, and how fast the spindle moves across the surface of the material.
Every CAD and CAM system has a varying array of features, skill requirements, learning curves, and cost. You'll have to do a little bit of research to find out which setup is right for you.
Step 3: Determine the Material
The Othermill interacts differently depending on the material you cut and the tool you use. As a result, it's really important that we know what sort of material we're working with before we attempt to cut anything.
The bezel we chose from our favorite craft store didn't have very good labeling, so we had to figure out what it was made from, or at least make an educated guess. We looked up a bunch of similar-looking bezels across a variety of crafting and jewelry-making online retailers. The bezels we found online were made of zinc. Since our bezel looked pretty similar to the labelled ones online, and since zinc seemed to be a reasonably common material, we made an educated guess and said our bezel was zinc (or close to it).
To make this easier on yourself, you can always find craft supplies that are clearly labelled from the get-go.
In order for your material to be cut safely and in the way you expect it to be cut, the settings need to work well with the tool and material you're using. If you generate your own G-code file, as we said before, you'll need to include the dimensions of the tool you're going to use, the speed of the machine's spindle (in revolutions per minute), and the rate at which the machine travels across the surface of the material (usually in millimeters or inches per minute). Machining shorthand for these settings is "Feeds and Speeds."
For example, in this file, we used a 1/32'' flat end mill, which we ran at a spindle speed of 12,000 RPM and a surface feed rate of 1mm/second.
Finding the optimal surface speeds and spindle speed to work with your tools and materials relies a bit on trial and error, consulting references such as machinery handbooks, and recommendations from tool manufacturers. Many machinists would say there's a certain amount of magic involved as well.
Step 4: Set Up Your File in Otherplan
If you'd rather not tackle the math right now and would just like a G-code file to play with, we've included the G-code files we used for the project. G-code files commonly end in .tap or .nc.
One file is a silhouette of our small friend Emma Danger's head, and one is of the engraving of her name. To make these files, we imported a photo of Emma into one of our favorite image-editing apps and traced her profile. This gave us a line we could cut out to make the silhouette.
After we sized the document correctly for our zinc bezel, we exported it to our CAM software, where we created something called a hole inlay toolpath out of it. A hole inlay is one of many ways of cutting through a layer of material exactly to specifications, and a toolpath is a generic term for a file that tells the machine how to cut the project. We then created an engraving toolpath for Emma's name, using the same dimensions we used to create the hole inlay toolpath. This will make sure the files line up correctly in the Othermill.
Download and open up Otherplan.
Halfway down the window on the right, under the Plans panel, you'll see the Import Files button.
Click the button and select your files from wherever you've saved them. They'll appear in Otherplan as panels of their own, as shown in the image.
Step 5: Set Up Your Tool
In Otherplan, click on the button in the Tool panel (top right). Select the tool you'll be using, in this case a 1/32'' flat end mill, and insert it into the Othermill's spindle when Otherplan prompts you.
Secure the tool with the handy tool wrenches that came with your Othermill. The larger wrench fits over the black collet nut at the bottom of the spindle, and the smaller one fits over the flat parts of the spindle itself. (The spindle is the spinning part that holds the tool. It sits behind the spindle motor and is connected at the top by the spindle belt.)
Once the tool is in the machine, follow the prompts in Otherplan to locate your tool and touch it off from the bed. This allows the machine to know where the tool is in space, so as to avoid damaging anything on the material or the machining bed.
Once the tool has touched off, the Othermill will return to home.
For a refresher on tool setup, check out our Getting Started guide.
Step 6: Set Up the Test Material
Before you cut your final piece of material, it's a good idea to try your file on a piece of scrap material, especially if you're just getting used to the Othermill.
We machined the first version of the file on a piece of anodized aluminum we had on hand. For small sizes, aluminum and zinc are reasonably similar in how they cut. Make sure the dimensions of your test scrap are roughly the same as your final piece, so you have a decent idea of what the final product will look like.
- In the Move By pane, select "Load/Unload material" (you can also select this in the Machine menu in the top menu bar, or use the ⌘L keyboard shortcut).
- Using your digital calipers, measure the width, height, and length of your material.
- Selecting Unload will bring the machine bed forward for easy loading. Secure your material to the bed with plenty of double-sided tape or hot glue. We find that for heavier materials, or for stuff you really want to hold down, a little hot glue along the edges of the material works great.
- In the Setup Materials pane, enter the dimensions you just measured.
You can also place your material anywhere you want on the bed and then tell Otherplan where the material is. This is helpful if, for some reason, you need to have the material in the center of the bed, or you'd like to place your design on something bigger but would like to use the same G-code you were already using. You can do this by entering in values in the Set Material Origin dialogue box, which appears after you hit Continue in the Setup Materials window.
You can also use the "Locate with tool" button and manually move the tool to wherever you'd like your material origin. Just follow the prompts in Otherplan.
Click Done and the material is all set!
Step 7: Test Your File
Double check all your material and tool settings and have a final look at the way your file renders on the bed in Otherplan. Make sure you have your safety windows in place, and if everything looks good to you, click on Cut in one of your file windows.
Otherplan will ask you if you're sure. If you are, click on Cut again and the machine will descend to the machining bed and start cutting!
Once the machine has finished one file, repeat the process for the other file. Since the tool needs to be changed in between jobs, Otherplan will prompt you to go through the tool-change sequence again once you've finished cutting your first file.
Step 8: Machine Your Jewelry
If your test piece comes out the way you want it to, you can cut your design on your final workpiece.
As you can see in the pictures, we used a wooden sacrificial layer under the bezel to protect the machine bed and to better see what we were cutting. If you do too, make sure to measure and include the thickness of the sacrificial layer along with your material thickness. Enter it into the Setup Material dialogue box as shown.
The frame around the jewelry bezel made determining the thickness of the part of the bezel we wanted to machine a little tricky, but as you can see in the photo, we used the nifty depth gauge on the bottom of the calipers to make a reasonable guess.
Secure your bezel and sacrificial layer to the bed. (Your sacrificial layer doesn't need to be this thick, but it should be reasonably substantial.) Double check your materials settings to make sure the dimensions of the actual piece match up in Otherplan. Since you have already set up your tool, you don't have to change anything in the tool panel, but it's a good idea to re-home the machine between files (re-home is under the Machine menu item on the menu bar).
Click on Cut once everything has been loaded and your safety windows are in place.
Step 9: The Results
If everything has been set up correctly, you'll end up with a lovely pendant. Emma Danger loves hers!
We found a chain we liked that was a good length and threaded it through the finding loop on the bezel. From here, we can use our speed and feed settings and experience making this piece to churn out loads of fun Othermill jewelry projects.
Confused? Frightened of G-code? Trying to figure out this whole crazy machining thing? We can help you! Leave us a comment with your questions, or email us at firstname.lastname@example.org. We'd love your feedback!