program, such as Aspire, SketchUp, Fusion 360, Rhino, Onshape, and others, Image 2.7. Once you’ve created a 3-D model, you need to save it in a CAM-compatible file format. The .stl file type is one of the most
Create your own 3-D model
Part preview
Image 2.7: Creating 3-D models can be accomplished with any one of several CAD modeling programs. Aspire (shown here) has a dedicated menu of 3-D modeling tools for creating single-sided models, such as the linen fold door. Creating a 3-D model takes time and skill, but fortunately, there are lots of CNC-compatible 3-D models available on the Internet that you can import into VCarve Pro, Aspire, or other CAD/CAM programs.
CNC Router Essentials
Design Essentials : 2
if the sign wasn’t CNC cut, study its layout and shape and then use those elements in your designs. If you see something you like, whether it’s painted, hand carved, laser engraved, or molded, grab the idea and archive it.
Think outside the box
As you look for ideas, don’t discount anything as a possibility. When you’re new to CNC, it’s easy to look at something and think it’s too hard. But as your skills increase, you’ll want to have more challenging projects. If you like it, capture it, and then figure out later how to execute it.
Keep your ideas organized
With today’s smartphones and tablets, and the fluid nature of the Internet, it’s easy to grab ideas no maer where you are. Maybe too easy, since it makes keeping all these files organized a challenge. There are many approaches to this with today’s technology. At a minimum, keep your ideas organized by category so you can find them as your collection grows deeper and deeper.
From inception to completion, you can let your creative juices flow with CNC work. Keep in mind that, in addition to wood, CNC machines can cut aluminum, brass, bronze, foam, and a variety of other materials. Start stockpiling those ideas!
size because an .stl shape is a wire mesh. As you scale up the model, the mesh becomes visible as flat triangular facets, which will also be visible in the final carving. The best defense against this is to use a high-resolution .stl designed for CNC design work and preview the .stl in the CAD/CAM soware before commiing it to your design.
Project inspiration
Where can you find project ideas? Well, a simple web search or a visit to Pinterest or Instagram will reveal thousands of pictures of CNC work. A lile more searching will reveal sites with ready-to-machine CNC project plans—some for sale and some for free. Aer you get some experience, lots of existing DIY shop projects (wood, plastic, aluminum) can be converted to CNC projects. It’s a great idea to network with other CNC owners: join a forum or a user group. Some of these groups hold meetings with show-and-tell time, providing a close-up look at completed CNC projects and the opportunity to ask questions about how the person made them.
Signs
Making signs is an immensely popular application of CNC machines and an excellent way to gain some experience at CNC project design and machining. Plus, existing signs are all around and can be a rich source of inspiration. You will learn a lot about sign design by just looking at existing signs in your neighborhood. Even
CHAPTER
Toolpath
Essentials
Once you draw a project in CAD, you then create toolpaths tocut the project. Seing up a toolpath requires a number of steps, but none are difficult or involve writing code. Plan to practice the steps virtually in soware a few times before making test cuts on your machine. In this chapter,you’ll learn about:
• Router bits for CNC
• Four frequently used toolpaths
• The importance of chip load
• Determining the best feeds and speeds
• The primary steps in seing up a toolpath
CNC Router Essentials
3 : Toolpath Essentials
rather than liing it, which can occur with an upcut bit. Because a downcut bit pushes the chips down when cuing, the chips usually get packed into the kerf. The packed-in chips will fall away when you separate the finished parts. If you need to remove them before that, try running the cut a second time to loosen up the chips and then remove them with compressed air or a vacuum.
Compression bits combine upcut and downcut shearing action in one bit and thus leave a clean cut on both the top and boom side of your material.
Router bits
Many of the bits you use with your handheld router or router table can be used in your CNC. There are also specialized bits for CNC that you will find useful. Carbide-tipped or solid carbide bits are the most commonly used bits on CNC routers because they stand up to abrasive materials such as MDF and plywood. However, due to their hardness, they are also more susceptible to breakage than high-speed steel (HSS). HSS also has the advantage of being less expensive than carbide, although HSS bits generally dull quicker.
You probably already own a few straight bits. These are good general purpose bits, but won’t give you the cut quality of a spiral bit. Spiral bits are available as upcut, downcut, or a combination, Image 3.1. Upcut bits act like a drill bit, pulling chips up out of the cut, which keeps the cuing path clear. The spiral creates a shearing action that reduces chipping and gives you a beer edge quality on your material than a straight fluted bit. An upcut bit may fray or chip the top surface of your material, but when through cuing, it provides a chip-free cut on the boom side.
Downcut spiral bits push down toward the material. This downward shear action provides chip-free cuing on the top surface but may cause chipping on the boom of some materials, such as melamine and plywood. Downcut spiral bits are also useful when cuing thin materials because the downcut pressure helps to hold the material against the bed
A router bit starter set
Image 3.1: Straight bits come in a variety of configurations. The four shown here are (left to right): straight flute, upcut spiral end mill, downcut spiral end mill, and compression end mill.
• 60 and 90° V-bits (V-carving) • "-, "-, and "-diameter upcut
