Beginners Guide to CNC Bits

Assorted carbide CNC router bits

Beginners guide to Bits!

The first thing to understand is that different bits are designed for different materials and cutting tasks. For example, a V-bit is often used for engraving, while a straight bit is better for cutting wood. Some bits are specifically designed to cut harder materials like metal, while others are better suited for softer materials like wood or plastic.
Another aspect to consider is the size and shape of the bit. The larger the bit, the more material it can remove at once, but it will also require more power and may produce more heat. Not all bits are designed the same and depending on the design this will dictate how the bit should be used and in what type of material.
Once you have selected the appropriate bit for your project, it’s important to use it correctly. This means using the correct speed and feed rate for the material and bit you’re using. The speed and feed rate will affect the cutting quality and the lifetime of the bit.
In general, it may take some experimentation and practice to become proficient in selecting the proper bits and using them correctly. But with time and experience, it will become easier to understand the best bit to use for your project and when and how to use it. It’s also important to consult the documentation and tutorials provided by the manufacturer, or online resources to gain a deeper understanding of the bits and their use.

Now lets talk Bits!
Basic Parts and terms for router bits

Shank: Shank is the part of the CNC bit that is inserted into the spindle or collet.
OAL (Over all length): Length of the bits from end to end.
CEL (Cutting edge length): Length of the cutting edge (flutes).

Flutes, why are they important and how come there are some many different kinds? Flutes are the cutting edge of your bit and they are responsible for removing the material from the workpiece, channeling the chips away from the cutting edge, and cooling the bit. The number, shape, and direction of the flutes can affect the type of cut and the overall performance of the bit. This is why it’s important to match correct bit with the correct application and material.
When you read/hear different names for bits that basically describing the flutes how they are shaped and what they do. Lets go over some common types and give a brief description.

Upcut: This means that when the bits is turned in a Clockwise rotation the the flute will direct the chips upwards. Moves the chips up out of the way, generally take a more aggressive cut and a faster speed. Leaves a better finish on the bottom side of but can leave chipout on the top surface.

Downcut: When the bits is turned in a Clockwise rotation the the flute will direct the chips downwards. General leaves a nicer top edge finish but can lead to chip out on the bottom surface. Chips are forced down which leads to more friction and heat build up.

O-Flute: O-flute bit is called that because of the shape of its flutes, which are rounded, “O” shaped. “O-flute” is designed for cutting soft materials such as plastics and aluminum, producing a very smooth finish, and generating less heat and dust than other types of bits. This flute style can also be in an Up-or Downcut.

Compression: Get it’s name because the cutting edge of the bit is designed in a way that it pushes the wood fibers together compressing them as it cuts, rather than pushing them apart. Taking advantage of the Upcut bottom section and a Downcut upper section this bit leaves a nice finish in laminated products such as plywood’s and melamine.

Straight flute: Straight flute bits have flutes which run straight up the length of the bit. Best suited for profile cutting and roughing these versatile bits can be used in a wide range of cutting applications in hard and soft material. The straight flute design helps evacuate chips and keep the bit cool. Keep in mind there are slight design difference for different materials so make sure your getting the correct style for your application.

Ball nose bit: These bits have a rounded end that allows them to create smooth and rounded edges on the material. They are commonly used for 3Ds carving and sculpting operations. Included in this category are tapered ballnose which taper down from the shank to the tip, these bits allow for a small cutting tip with the added strength of the larger diameter.

Vbits: These bits have a V-shaped edge that allows them to create V-shaped grooves in the material. Available in many styles and varying degrees, they are commonly used for sign-making and engraving operations.

These are the most popular bits with the hobby level woodworking, sign making CNC’s. This is not an exhaustive list, there are many other types and variations of CNC router bits that are designed for specific applications and materials.

Leave a Reply

Your email address will not be published. Required fields are marked *