3D Printer Users

Hello, 3D printer users! We’re excited that you’re interested in using the Othermill. This guide illustrates the similarities and differences between a 3D printer and the Othermill and helps you use your knowledge of additive manufacturing to get a leg up on subtractive manufacturing.

Both a 3D printer and the Othermill are CNC machines, meaning that they use designs generated on a computer to automatically and precisely manufacture 3D objects. The main difference is that a 3D printer begins with a blank space and builds successive layers of material, whereas the Othermill begins with a solid block of material and uses a spinning cutting tool to carve away successive layers of material.

A consumer-level 3D printer is also usually limited to a few types of plastic, whereas the Othermill works with a wide variety of materials, including plastic, wood, and metal. The other big difference is that with a 3D printer, you can grab an .stl file, load it into the software, and start printing. With the Othermill, milling 2D shapes is just as easy, but 3D shapes can be a little more complicated. Check out our CAD and CAM guide and read on to learn more about the process.

How It Works

A 3D printer begins with an empty print bed. The print head builds up thin layers of plastic according to (usually) an .stl file that the user loads into the machine software. If it’s a hollow object, the machine can be set to fill in the empty space with structural plastic to make the object more rigid. The layers build up until the object is complete.

When a job is set up optimally, the head moves as fast as possible without compromising print quality. The print quality can vary from very fine detail to very coarse detail, depending on the user’s needs.

The Othermill begins with a solid block of material. The head moves the spinning cutting tool through the material according to toolpaths, which are generated from CAD (computer-aided design) models or drawings. The process of generating toolpaths is called CAM (computer-aided manufacturing). A 3D printer follows toolpaths too, but it’s all done under the hood.

When a job is set up optimally, the head moves as fast as possible while still allowing the cutting tool time to cut away the material. The settings to achieve this are highly dependent on the material being milled and the tools being used to mill it, which is why you can’t just load up an .stl file and hit go. That being said, the design process for a 3D printer has many similarities to that of the Othermill.

3D Design

Typically, 3D design begins the same way for both 3D printers and the Othermill: creating a 3D computer model of the object you want to make. Conveniently, the same software can be used for both machines. After modeling, a 3D printer user will usually generate an .stl file for the 3D printer to use. An Othermill user will need to generate toolpaths from the model using a CAM program before generating a G-code file for the Othermill to use. Our CAD and CAM guide explains this process in detail and also gives software recommendations.

If you’re using a 3D scanner or downloading files from Thingiverse, you’re most likely going to end up with .stl files. This is the most difficult case, but it’s sometimes still possible to mill them on the Othermill by converting them to solid models. The process is not guaranteed to work, but if your STL mesh doesn’t have too many holes or other problems, and if it has fewer than 30,000 faces, it will often work fine.

What if I can’t or don’t want to convert my STL to a solid?

If you can’t or don’t want to convert your .stl to a solid, you can use either Vectric’s Cut3D or MeshCAM to generate toolpaths directly from .stl files. Both of these programs will allow you to select parts of your model to machine and generate toolpaths that the Othermill can use to mill your object. Cut3D is $299 and runs on Windows. MeshCAM is $250 and runs on Mac and Windows, but it doesn’t include the command to start the spindle. Our support team can help you with a simple workaround if you’d like to use MeshCAM.

2D Design

On the other hand, 2D design is very simple for both a 3D printer and the Othermill. With a 3D printer, you make a sketch, decide how thick you want it, and hit print. There are even iPad apps that allow you to draw a shape with your finger and sends it directly to the printer. With the Othermill, you still need to use CAM software to convert 2D designs to G-code toolpaths. Read our CAD and CAM guide to learn more.

Materials

One big difference between a 3D printer and the Othermill is the variety of materials that can be used with each. While the average consumer 3D printer can only print in a few types of plastic, the Othermill can mill pretty much any type and thickness of wood, most metals softer than steel, FR-1 circuit boards, modeling foam, wax, and most plastics. The limits, other than needing to fit inside the machine, are mostly governed by the material’s heat-transfer properties. For example, the reason the Othermill can’t cut steel is because heat builds up where the material is being cut and melts the tool. Melting is also an issue for some materials, such as ABS plastic. Check out our handy list of materials to learn more.

3D Printer or Othermill?

Choosing the best tool for your project depends on the nature of the project. For fast prototypes of complex 3D shapes, figurines, sculptures, architecture models, product enclosures, and bottle openers, a 3D printer is great. However, the Othermill really shines with projects like small parts made of wood or metal, stamp making, mold making, parts that need to be structurally strong and/or dimensionally accurate, engravings of all kinds, product enclosures in various materials, and of course circuit boards.

3D Printer and Othermill!

But who says you have to pick one or the other? Some people have made an initial print with a 3D printer and then used the Othermill to fine-tune it. Additive and subtractive manufacturing have a lot of potential when used together. The only limit is your imagination.

Swarf

While 3D printers have the convenience of zero waste (unless you mess up a print), printing only what’s necessary and nothing else, the Othermill, like all CNC machines, accumulates swarf as it mills. Swarf is the term used to describe any kind of dust, chips, or other debris that is removed by the cutting tool during milling. Swarf needs to be cleaned up, ideally with a vacuum.

Overhangs

Something to be aware of when designing your project is that the Othermill, like all three-axis CNC mills, can’t mill overhangs. Overhangs are elements of a design that have an underside, as opposed to being solid all the way to the bottom. In 3D printing, they often require support structures underneath them. Since the Othermill machines from the top down, it can’t mill underneath an overhang. However, it’s often still possible to make an object that has overhangs if you machine it from the side.