What Rotary Bit/Cutter to Use

Choosing the proper tools for any project is essential for ensuring a good outcome, whether it’s a small job like painting a room or a big job like engraving signage for a new build.

For example, although painting a room with watercolor paints and a small brush would technically get the job done, using paint specifically designed for interiors, a roller brush, and painters’ tape will provide the painter with a much better outcome and in a lot less time.

This same principle can be applied to sign fabrication. Just like choosing the right paint brush, choosing the right engraving bit can be the difference between an efficiently made sign and a slow painful process. Put simply, selecting the right router carving bits will significantly improve your efficiency and quality of work, which means you’ll make more profit.

Understanding the types of rotary engraving, key terminology, and material compatibility will help make choosing the right cutter or bit easy!

Types of Rotary Engraving

First, it’s important to understand the different types of rotary engraving. The most popular type of rotary engraving involves using a cutter or bit to remove material from the substrate.

The second, less common, method of rotary engraving is called diamond drag engraving. This is a method that utilizes a non-rotating diamond-tipped tool to etch a mark into the surface of the substrate.

Rotary engraving is often used when deep cuts are needed and is extremely versatile in the types of materials it can be used with. Diamond drag is best for fine details and creating delicate markings on metals and other hard surfaces. Engraving a design using diamond drag also creates contrast on single-ply materials and surfaces that do not possess a contrasting color that can be shown through the traditional engraving method of using a rotating bit.

Rotary engraving is an often overlooked, but extremely powerful engraving technique. This technique allows fabricators to create beveled edges, varying degrees of depth, and even ADA signage with braille. Because this technique relies on physically removing the material to create marks, rather than a focused beam of light, the type of tool that you choose to remove the material is key!

Definition of Bits and Cutters

Do you remember the first time you set foot in a home improvement store with a paint swatch and a dream? You may have felt overwhelmed standing in the paint-tool aisle, unsure of which brush to pick when faced with so many options. Embarking on your rotary engraving journey may feel similarly daunting, as you look at all the different options available for cutting and marking. However, once you understand the key differences and terminology, you’ll become a pro at selecting the best bit/cutter every time, for every job, with confidence.

Here are some key cutter/bit terms to familiarize yourself with:

• Tool: The rotating or non-rotating carving bit that is used to remove a substrate’s surface

• Micrometer: An adjustable dial attached to the bottom of the spindle that controls engraving and cutting depth

• Nose Cone: Attaches to the bottom of the spindle’s micrometer, which normally pushes against the material’s surface during engraving. The chip removal system attaches to the nose cone and allows the material chips to be removed from the substrate during the engraving or cutting process.

• Engraving Depth: The depth to which the cutter removes material from the substrate.

• Flute: A groove milled into the side of the tool tip that creates space for engraved chips to be removed from the tool tip during engraving. Tools can be single fluted, meaning they have only have one opening for chip removal and one cutting edge. Single-flute straight tools may also be called FLX bits. There are also double and multi- fluted straight tools that offer a smooth edge cut. When using double or multi-fluted tools, the engraving feed rate may need to be reduced and/or spindle speed increased to avoid jamming and clogs.

• Chip Removal System: The system that lifts away chips when attached to nose cone during the engraving and cutting process.

• Spiral: The helical shape of the fluting on some bits, which aids in smoother cuts.

• FLX Bits: Bits that are meant for use with soft materials and commonly used on plastics.

• Common tip sizes: .005” to .125” – This width will determine how wide of a path the tool will create.

• Common shank sizes: 1/8”, 11/64” and ¼” diameter – Refer to the rotary engraver manual to see which shank sizes fits the spindle

Choosing the Right Cutter: A guide

Now that you understand the terms and tool options available, we can discuss what factors you’ll consider when choosing your bit/cutter. To return to our painting example, once you understand that rollers are for large spaces and walls and brushes are for fine details and cutting-in, picking the right paintbrush for your job is much easier! The same goes for selecting your bit.

Firstly, understand the material you’re working with. If it’s a soft material such as plastic, wood, or acrylic, you’ll likely be using a rotating bit for engraving. If you are marking on hard material like metal or glass, you’ll most likely utilize the diamond drag technique, using a non-rotating diamond drag tool.

Second, consider your artwork and design. Is this a detailed piece or does it have bold text and letters that are meant to be easily legible, like a restroom or egress sign? For bold, simple designs an FLX bit is a good choice because you can create varying widths depending on the tip width you choose. If you need to create a detailed and intricate design, refer to a small width rotating bit or non-rotating diamond drag bit, depending on your material type.

However, don’t discount FLX bits entirely for more detailed engraving. For example, tools with smaller tip widths will produce much more precisely engraved lettering and graphics where small sharp edges and corners are important to produce accurately.

This brings us to the next point to consider – time. Consider how much time you have to complete the job. If you need to complete a job quickly, choose a bit with a higher flute count, for smoother faster cuts. If precision and fine details are more important than engraving time, you can choose to use a more precise bit with a smaller tip width.

By following these steps and understanding the basics of rotary engraving, you can ensure a successful and efficient engraving project every time.

Material Compatibility with Rotary Engraving

Selecting the right cutter depends on the material you are working with. Here is a breakdown of material compatibility:

FAQs About What Rotary Bit/Cutter to Use

How do I determine the correct engraving depth? A: Use a micrometer to measure and set the appropriate depth based on the material thickness and desired effect. For engraving plastics, reference the recommended engraving depth.

What bit should I use for detailed engravings? A: For detailed engravings, choose a fine-tip diamond drag tool or FLX bit with a small cutter width.

Can I use the same cutter for all materials? A: It is not recommended. Different materials require specific cutters to achieve the best results without damaging the tool or material.

How do I avoid melting acrylic during engraving? A: Use a spiral flute bit at a slower speed, reduce the spindle speed and feed rate if needed. Run several passes at less engraving depth instead of one pass at a very deep engraving depth. Remove the protective masking from the substrate surface before engraving. Ensure that the chip removal system is completely removing the chips during the engraving or cutting process.

Refer to this blog or reach out to advanced support team when you have questions about choosing the right bit for your job! You can also find great resources like article, Rotary Engraving: The Seasoned Veteran of Professional Marking, on the JPPlus website and in trade publications.