CNC

Router

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Fundamentals 1

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• Basics of CNC Machining
• Intro to CNC Routers
• Capabilities
• Material/Machine Setup
• CNC Router Bits

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Subtractive vs. Additive Manufacturing

Additive:

• 3D Printing
• Powder bed fusion
• Material extrusion

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Subtractive:

• Laser cutting
• Drilling, sawing, sanding, etc.
• Milling and Turning

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CNC Routers

CNC Routers

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• Subset of CNC machines ideal for cutting softer materials with low cost/time
• Most commonly used with:
• Wood - plywood / MDF / Hardwood
• Plastics - acrylic / polycarbonate
• Foam
• Limited use of thin, soft metals

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CNC Routers can be used to make a wide variety of products.

While there are a lot of applications for CNC routing, the top five are (according to CAMaster):

1. Cabinet making
2. Sign Making
3. Woodworking
4. Instrument Production
5. Rapid prototyping - Wooden prototypes are a quick and cheap way to test your design!

Image from Cabinet Design Software

Starbucks Coffee Sign Made by a CNC Router Image from CAMaster

Image from GN Tech

Image found here

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The Laguna Router

The Laguna Smartshop II has a 4’ x 8’ processing area and is ideal for large projects or 3D toolpaths

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Anatomy of a CNC Router

Diagram by Vectric

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Technology Evaluation - Benefits

• Faster and more efficient than manual machining
• Automated process makes repeated parts very efficient
• Further automation, such as tool changes, can reduce time further
• Higher quality than manual machining
• CNC router specifications:
• Accuracy: 0.002 - 0.004”
• Repeatability: ≤0.008”

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Technology Evaluation - Drawbacks

• Large CNC routers are very expensive, upwards of $40,000
• Newer desktop CNC machines can be purchased for less than $1,000
• Barrier to entry
• Knowledge of CAD/Toolpath processing is required

The improved processing times, flexibility, automation, and accuracy of these machines can make up for the large capital expenses.

Cost

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When to Choose CNC Router over Laser cutter

A laser cutter is significantly faster than a router for cuts within its capabilities.

The CNC router comes in handy for cuts that are thicker than a half inch or pocket cuts that do not go through the entire material.

Additionally, a CNC router is capable of cutting 3d shapes.

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2D versus 3D cuts

The vast majority of DI Lab projects are 2D, however our cnc routers are capable of cutting 3D toolpaths.

Shown here is an STL file, the most common 3D filetype.

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History Intermission!

When was the first numerical controlled machining process used?

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Prior to this, all machining operations were performed manually by experienced machinists

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History Intermission!

1949

Motivation: The Parsons Corporation began manufacturing helicopter and airplane parts, eventually realizing that the machining needs for advancing airplanes were far beyond human capacity. After working on the NC machining process for years, Parsons finally received funding from the Air Force and, not long after, attracted attention from MIT and IBM.

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CNC Machining Basics

CNC - Computer Numerical Controlled

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Clamping Techniques

Your material must to be secured to the machine bed in some way to prevent material from moving during the cut

1. Screws, nails, bolts (secured into the spoil board)
2. Double-sided tape
3. Toggle clamp
4. Toe clamps
5. Vacuum

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Be sure not to put any clamping mechanisms in the way of the toolpath!

Toe Clamps

CNC Router Bits

Tool Selection

Most cutters used on a CNC router are called endmills, and have 1-4 “flutes” with a sharp cutting edge.

• Lateral cuts (X/Y)
• Plunge cuts (Z)
• Engraving
• 3D surfacing (ball)
• Facing

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Types of CNC Router Bits

There are four main tool types used for this type of machining:

Flat End Mill

Ball End Mill

V-Carve

Engraving

Images by Tinker and Futz (last image unknown)

Types of CNC Router Bits: Flat End Mill

Flat end mills are the most general purpose router bits.

Image Unknown

• Best for flat workpieces
• Used with the fastest feed rates
• Cannot cut round edges

Types of CNC Router Bits: Flat End Mill

Flat end mills are the most general purpose router bits.

Image Unknown

• Upcut bits push the removed chips upward and away from the workpiece. This gives a better surface finish on the bottom face and allows for faster processing times. It is not recommended to use this geometry for soft or thin materials as they could be pulled away from the machine bed during processing, damaging the workpiece and presenting a safety hazard.

Types of CNC Router Bits: Flat End Mill

Flat end mills are the most general purpose router bits.

Image Unknown

• Downcut bits are best for thinner materials (<⅛” thick). Chips will be pushed downward; therefore, chip extraction is less effective. Slower processing speeds are required. Use downcut bits when the top surface requires a high quality finish.

Types of CNC Router Bits: Ball End Mill

Ball end mills have rounded edges. All have upcut geometries.

Image by WalzCraft

• Can be used to process more complex 3D workpieces
• Most commonly used for fluting
• Cannot cut flat edges, not suited for holes

Fluting

Types of CNC Router Bits: V-Carve

V-Carve bits use slower speeds than both flat end or ball end mills. These tools are used for detailed work.

Images Unknown

• Commonly used for miter cuts, slots (second image), and chamfered/bevelled edges
• Can also be used to engrave letters/symbols/etc.

Types of CNC Router Bits: Engraving

Engraving bits have the slowest speeds of all the tools. They are used to create very fine detail.

Image by Red Bot Machinery

CNC Router Bits: Flutes

Flutes are the cutting edges on the bit. The number of flutes vary. These general guidelines by Wikimal can be used to help select a tool.

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Diagram by Popular Woodworking

Single Flute: Allows for larger chiploads in softer materials

Double Flute: Allows for better part finish in harder materials

Multiple Flutes: Allows for an even better part finish in harder materials

As the number of cutting edges increases, your feed rate should increase to prevent burning and premature tool dulling. More flutes reduce chip load and improve surface finish if feed rate remains the same. The most common flute numbers for general milling operations are two (better space for chip ejection) and four (better surface finish).

End of Fundamentals 1

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