Use CNC Router CAD to Create Six Tables

Digital woodworking comes with a lot of moving parts: new hardware; new software; new methods and skills. But it’s the machinery itself that gets most of the attention. CNC Routers, Laser Cutters and 3D printers are all impressive machines. Watching them work, and the resulting precision, is the main focus of this new way of woodworking. With all that amazing machinery magically moving around, it’s easy to miss the most important part of digital woodworking. As you get more used to this new world, you start to realize that the most powerful tool is not the one you thought it would be. Yes, the hardware delivers all the expected benefits of precision and repeatability. But it’s really the software design tools and how you use them that really opens up your mind to new methods, new ideas and a new way of thinking. Despite computers and the fancy digitally controlled machinery, this is where the real power resides in digital woodworking.

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Case in point. Each year in late spring, I teach a five-day class at the Marc Adams School of Woodworking that’s a hands-on introduction to digital woodworking.  Besides the basics of how the software and machinery work, the main objective is to build a project using these new tools. For that, each student makes a modern hall table —  the parts of which will be machined on a CNC Router. In a typical class, this would mean building just one table design. But as a designer equipped with good CAD design tools, I just couldn’t leave well enough alone. So I created six different table designs for the students to choose from – and one of them is simple; it’s meant to be a stepping-off point for motivated students to develop their own variations.

Six Tables are Better Than One

Creating six table designs is definitely more work than one, but the tools for creating designs in CAD software are very powerful. Once you realize that you can clone one table and use its general layout and dimensions as a starting point for a new design, things start to get interesting. And, because the process of creating a new design based on an existing one is so flexible, you resist the natural inertia to stop with just one. Creating in CAD is quite a bit different than sketching out small thumbnail designs in a sketchbook where you naturally want to be loose. I sketch and draw all the time. But once in CAD, you are working on full-scale working drawings that, if created precisely, can be used for cutting parts on a CNC Router. The big benefit is that you can produce lifelike 3D renderings of different variations to evaluate before you commit to building them.

You can take it a step further. With CAD software and a CNC Router machine, it’s easy to make something you can see and touch in the real world. Once I completed the six hall table designs, I thought it might be useful for students to look at actual tables. So over a couple of hours, I made half-scale versions of all six of the tables out of poplar. Because I have to ship the models to the school, I made them knock-down so they fit in a small case to be assembled on site. Now, students have a chance to see the tables in person before making the choice of which full-size version to build.

Learning More by Doing More

And that gets to an important lesson about digital woodworking. Because of the power of CAD software, you can create more than one design. You can create variations that you can try out on screen in renderings or scaled models that can be machined on a CNC Router machine. Renderings are terrific, but there’s nothing like seeing and touching something in the real world. From a designer’s perspective, the benefits go well beyond making alternate versions of the same table; it’s also about refining your design. Any tool that encourages you to hone in and tweak the design and the details is very powerful. If you’re methodical, your designs get better and better as you refine them. This is the secret of automobile designers. They develop their designs with highly skilled hand drawings, take them into CAD for precision and to refine and tweak them. Next, they’ll make scaled clay mock-ups to further evaluate and refine the design. Finally, they make full-size mock-ups to see the work in different lighting situations and refine the designs even more.

Digital Woodworking Tools are Powerful Creative Tools

The power of digital woodworking tools in creative hands is considerable. Never is this more apparent than in the use of CAD drawing software. Going beyond your first design, developing variations and continual refinement are powerful techniques a designer uses to make a good design into a great design. As I’ve said in the past, you don’t have to own a CNC Router to get most of the benefits out of digital woodworking. Good CAD software is a powerful tool that makes the process of variation and refinement much easier. And that makes your designs better. Good design and CAD software are the real secrets of digital woodworking. And whether you’re a hand-tool woodworker, a hybrid woodworker or a newbie digital woodworker, using digital design tools to develop and refine your designs is just as powerful.

Ways to Digitalize CNC Routers for Woodworking

There are a lot of ways to do woodworking.

For example, there’s more than a dozen ways to make mortises and tenons. The same is true for almost everything a woodworker does. For any given task, everyone finds a way to do it that fits how they work or a particular situation. For most of us, woodworking is a combination of hand and machine tools and techniques. If you’re making a living as a furniture maker as I do, you probably tend to be more pragmatic in your choices and lean a bit harder on machines for added efficiency, accuracy and time saving.

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5 axis CNC Router

As if there weren’t already enough options, there’s something new to consider. Thanks to lower prices and better designs, woodworkers can now add digitally controlled tools to their workshop. Yes, we’re talking about computers, software and CNC routers. How they work and the range of what they can do for woodworkers is unlike anything we’ve seen in the past.

I’ve discovered that with the right approach and a clear understanding of how to use digital tools in conjunction with hand tools and power tools, they can be great additions to a shop – the best of all worlds.

So, let’s take a peek into the world of technology, CNC Routers and digital wood-working.

Learning to Program a CNC Router

CNC or Computer Numerical Control is growing in importance in schools. This section is an introduction to CNC Router machining and explains in simple terms the equipment needed and how it can be used.

Have you ever used flashcards or CDs to learn a foreign language? To learn a new word, you read it from a card or listen to a native speaker say it in the new language, then you get an English translation. I think you can take a similar approach to learning G code, the programming language that controls CNC routers.

G-code is simple, and every machine uses it. Commercial machines come with fancy software that adds some proprietary code to every program, but the basic commands are always the same. I’ll translate some G-code into English so you can see how it works.

You can learn to program a CNC router with a few basic commands that can be mastered in a day or two.

Software for CNC Router Programming

You don’t have to learn G-code to create CNC Router programs. There’s software that will write the code for you, but it can be expensive. If you learn a few G-code commands, you’ll be able write your own programs without spending a dime. You can create a CNC program in any text editing application. All you have to do is type your code in plain text and save the file with the right extension (.nc or .gcode). There are other extensions that will work, but these two are the most common. Load the file in your CNC Router control software and run the program.

CNC Router Phrases

Whether you want to cut a straight line or an arc, drill a hole or route a pocket, you need to use the appropriate command. Think of G-code commands like phrases in a foreign language. Here’s a list of CNC Router phrases to get you started.

• G0: Move at full speed to a specific point
• G1: Cut a straight line
• G2: Cut a clockwise arc
• G3: Cut a counterclockwise arc
• G40: Cut right down the center of the line
• G41: Cut to the left of the line by the tool’s radius
• G42: Cut to the right of the line by the tool’s radius
• G20/G21: Coordinates are in inches/Coordinates are in millimeters

Syntax

You tell a CNC machine what to do by typing a command, followed by coordinates. If you want to cut a straight line, your code might look something like this:

G1 X3 Y0

In English, this means Cut a straight line that ends at 3” in the X-axis and 0” in the Y. Check out these G-code commands, followed by their English translations.

• G0 X10 Y0: Move full speed to 10” in the X-axis and 0” in the Y-axis.
• G1 X15 Y15: Cut a straight line ending at 15” in the X-axis and 15” in the Y-axis.
• G2 X1 Y1 R0.5: Cut a clockwise arc with a ½” radius ending at 1” in the X-axis and 1” in the Y-axis.

As you can see, some commands require additional parameters. The G2 command above is followed by a parameter for the arc’s radius. You’ll see the parameter P below, which is used with tool radius compensation. Check out this link for more information about G-code parameters.

Tool Radius Compensation

In all of the above examples, the router bit will be centered over the X and Y coordinates. When this is true, the final size of whatever you’re cutting will be smaller than the specified dimensions by the diameter of the bit. To fix this, you have to use a G41 or G42 command, which initiates tool radius compensation. Take a look at these bits of G-code and their English translations.

• G41 P0.125: Compensate for the router bit’s radius by cutting 1/8” to the left of the specified X and Y coordinates.
• G42 P0.125: Compensate for the router bit’s radius by cutting 1/8” to the right of the specified X and Y coordinates.

Example Program

To program this part on a CNC router, we need to know all the coordinates shown here.

Let’s look at the code required to cut the 4” x 4” part shown above. If this part is 3/4″ thick, we’ll need to make several shallow passes to cut all the way through the material. The following code will give us a 1/8″ deep cut. To get to full depth, we’d simply repeat the code several times, adding -.125 for each pass to the Z coordinate in the second line. The first line of code is what’s called a lead-in move, which gives us room to initiate tool radius compensation.

G0 X-1 Y-1
G1 Z-0.125 (add -.125 to this line for each pass)
G42 P0.125
G1 X0 Y0
G1 X4
G1 Y3
G3 X3 Y4 R1
G1 X0
G1 Y0
G1 Z0.2
G40

Here’s how this translates to English:

• G0 X-1 Y-1: Move at full speed to -1” in X and -1” in Y.
• G1 Z-0.125: Plunge 1/8” into the material.
• G42 P0.125: Compensate for the router bit’s radius by cutting 1/8” to the right of the specified coordinates.
• G1 X0 Y0: Cut a straight line ending at 0″ in X and 0″ in Y.
• G1 X4: Cut a straight line ending at 4” in the X.
• G1 X3: Cut a straight line ending at 3” in the Y.
• G3 X3 Y4 R1: Cut a counterclockwise arc with a 1” radius, ending at 3” in X and 4” in Y.
• G1 X0: Cut a straight line ending at 0” in X.
• G1 Y0: Cut a straight line ending at 0” in Y.
• G1 Z0.2: Retract the bit so that it’s .20” above the material.
• G40: Turn off tool radius compensation.

·         When using tool radius compensation, think about the direction of the cut. If you’re moving clockwise, cut to the left of your coordinates. For counterclockwise cuts, compensate to the right. You may need to experiment to get the hang of tool compensation.

·         Speaking/Writing G-code

·         Practice using the G0, G1, G2, G3 and G40/41/42 commands by writing some simple programs. You can download a G-code viewer here that will let you see the results of your code. Try programming in millimeters by writing G21 in the first line. When you know these commands, you know enough G Code to create all sorts of CNC programs.

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5 axis CNC Router

Building a CNC Router Cuts Down Half of the Expenditure

Have you ever seen all the new CNC Routermachines available to hobbyists these days? Everybody who sells woodworking tools seems to carry at least one model. Maybe you’ve been thinking about buying one. If you’re computer savvy, you could have a lot of fun with a CNC router. On the other hand, you might be hesitant to spend upwards of $2000 for this technology.

Adding CNC to your shop doesn’t have to cost a small fortune; you can build a sturdy and accurate three-axis CNC router for about $1000, and that price tag will get you most of the features you’ll find in commercial models selling for $3000-$4000.

You’ll need some kind of sheet material to make the machine’s body, and that can be MDF, plywood, UHMW or HDPE plastic, aluminum or steel. I recommend using something that’s at least ¾” thick so that you end up with a rigid frame. To stay within the $1000 budget, choose MDF. It’s flat, easy to work with and inexpensive.

Each axis will require a combination of guide rails and bearings for motion. There are plenty of choices for these components, but aluminum rod is an easy option and won’t cost as much as most of the others. Just make sure the rod diameter is large enough that the shafts won’t sag. You can also drill and tap holes in the shafts and mount them to the machine’s frame. You’ll have to cut notches in the bearings, or buy bearings that are made for this type of mounted shaft.

The bearings can be made of ¾” thick UHMW plastic, which is a low-friction material that’s easy to machine with standard woodworking tools. To make a bearing out of plastic, just drill a hole the same diameter as the corresponding shaft. I like to split the shaft hole with a saw kerf, which allows the bearing to slide a little more easily. Drill and tap some mounting holes in the edge of each bearing and attach the bearings to the machine with bolts.

The easiest way to drive each axis is with a lead screw and nut. You can be super-thrifty and use threaded rod, but this won’t give you the kind of accuracy CNCs are know for, so I suggest ACME screws. These screws have trapezoidal threads and can work with special anti-backlash nuts that reduce slop.

You can buy a kit with the motors and all the required electronic components for as little as $100, but at this price, you won’t get an enclosure for these parts to protect them from damage or exposure to dust, water or other harmful materials. A few manufacturers make what are called “drive box kits” that include an enclosure, and are usually simpler to connect than the cheap kits you have to wire up yourself. Both types of kits require a PC with a printer port, or parallel port. You’ll also need the controller software, and there’s an excellent program called Mach 3 that will get you up and running for $175.

Three-axis routers are simple machines, and once you understand how they work, you can easily build one with a few basic tools. Although building a router doesn’t require any computer skills, using one certainly does. You need to be computer literate to setup, program and operate your new router.

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5 axis CNC Router 

Do You Know How to Program a CNC Router?

Have you ever used flashcards or CDs to learn a foreign language? To learn a new word, you read it from a card or listen to a native speaker say it in the new language, then you get an English translation. I think you can take a similar approach to learning G code, the programming language that controls CNC routers.

G-code is simple, and every machine uses it. Commercial machines come with fancy software that adds some proprietary code to every program, but the basic commands are always the same. I’ll translate some G-code into English so you can see how it works.

Software for CNC Router Programming

You don’t have to learn G-code to create CNC Router programs. There’s software that will write the code for you, but it can be expensive. If you learn a few G-code commands, you’ll be able write your own programs without spending a dime. You can create a CNC Router program in any text editing application. All you have to do is type your code in plain text and save the file with the right extension (.nc or .gcode). There are other extensions that will work, but these two are the most common. Load the file in your CNC control software and run the program.

CNC Router Phrases

Whether you want to cut a straight line or an arc, drill a hole or route a pocket, you need to use the appropriate command. Think of G-code commands like phrases in a foreign language. Here’s a list of CNC Router phrases to get you started.

• G0: Move at full speed to a specific point

• G1: Cut a straight line

• G2: Cut a clockwise arc

• G3: Cut a counterclockwise arc

• G40: Cut right down the center of the line

• G41: Cut to the left of the line by the tool’s radius

• G42: Cut to the right of the line by the tool’s radius

• G20/G21: Coordinates are in inches/Coordinates are in millimeters

Syntax

You tell a CNC Router machine what to do by typing a command, followed by coordinates. If you want to cut a straight line, your code might look something like this:

G1 X3 Y0

In English, this means Cut a straight line that ends at 3” in the X-axis and 0” in the Y. Check out these G-code commands, followed by their English translations.

• G0 X10 Y0: Move full speed to 10” in the X-axis and 0” in the Y-axis.

• G1 X15 Y15: Cut a straight line ending at 15” in the X-axis and 15” in the Y-axis.

• G2 X1 Y1 R0.5: Cut a clockwise arc with a ½” radius ending at 1” in the X-axis and 1” in the Y-axis.

As you can see, some commands require additional parameters. The G2 command above is followed by a parameter for the arc’s radius. You’ll see the parameter P below, which is used with tool radius compensation. Check out this link for more information about G-code parameters.

Tool Radius Compensation

In all of the above examples, the router bit will be centered over the X and Y coordinates. When this is true, the final size of whatever you’re cutting will be smaller than the specified dimensions by the diameter of the bit. To fix this, you have to use a G41 or G42 command, which initiates tool radius compensation. Take a look at these bits of G-code and their English translations.

• G41 P0.125: Compensate for the router bit’s radius by cutting 1/8” to the left of the specified X and Y coordinates.

• G42 P0.125: Compensate for the router bit’s radius by cutting 1/8” to the right of the specified X and Y coordinates.

Example Program

Let’s look at the code required to cut the 4” x 4” part shown above. If this part is 3/4″ thick, we’ll need to make several shallow passes to cut all the way through the material. The following code will give us a 1/8″ deep cut. To get to full depth, we’d simply repeat the code several times, adding -.125 for each pass to the Z coordinate in the second line. The first line of code is what’s called a lead-in move, which gives us room to initiate tool radius compensation.

G0 X-1 Y-1

G1 Z-0.125 (add -.125 to this line for each pass)

G42 P0.125

G1 X0 Y0

G1 X4

G1 Y3

G3 X3 Y4 R1

G1 X0

G1 Y0

G1 Z0.2

G40

Here’s how this translates to English:

• G0 X-1 Y-1: Move at full speed to -1” in X and -1” in Y.

• G1 Z-0.125: Plunge 1/8” into the material.

• G42 P0.125: Compensate for the router bit’s radius by cutting 1/8” to the right of the specified coordinates.

• G1 X0 Y0: Cut a straight line ending at 0″ in X and 0″ in Y.

• G1 X4: Cut a straight line ending at 4” in the X.

• G1 X3: Cut a straight line ending at 3” in the Y.

• G3 X3 Y4 R1: Cut a counterclockwise arc with a 1” radius, ending at 3” in X and 4” in Y.

• G1 X0: Cut a straight line ending at 0” in X.

• G1 Y0: Cut a straight line ending at 0” in Y.

• G1 Z0.2: Retract the bit so that it’s .20” above the material.

• G40: Turn off tool radius compensation.

When using tool radius compensation, think about the direction of the cut. If you’re moving clockwise, cut to the left of your coordinates. For counterclockwise cuts, compensate to the right. You may need to experiment to get the hang of tool compensation.

Speaking/Writing G-code

Practice using the G0, G1, G2, G3 and G40/41/42 commands by writing some simple programs. You can download a G-code viewer here that will let you see the results of your code. Try programming in millimeters by writing G21 in the first line. When you know these commands, you know enough G Code to create all sorts of CNC programs.

Sign up for Build a CNC Router from Popular Woodworking University for complete plans, drawings and instructions for building your own CNC machine. You’ll learn even more about G-code.

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CNC Router Machine - A Brief Introduction

CNC Router Machine - A Brief Introduction

In Industry it is not efficient or profitable to make everyday products by hand. On a CNC machine it is possible to make hundreds or even thousands of the same item in a day. First a design is drawn using design software, then it is processed by the computer and manufactured using the CNC machine. The machine featured below is the BOXFORD DUET.

This is a small CNC machine and can be used to machine woods, plastics and aluminium. In industry, CNC machines can be extremely large. The Duet is one of the smaller CNCs and is ideal for use in schools.

Have a look at the photograph on the right. Can you imagine how long it would take a skilled worker to ‘carve’ this shape out of wood or a soft material - it would probably take a full day. We will be going through its manufacture, one step at a time using a CNC machine (next page). How long do you think manufacturing this product with a CNC machine will take ?

The VICE: This holds the material to be cut or shaped. Material must be held securely otherwise it may 'fly' out of the vice when the CNC begins to machine. Normally the vice will be like a clamp that holds the material in the correct position.
The GUARD: The guard protects the person using the CNC. When the CNC is machining the material small pieces can be 'shoot' off the material at high speed. This could be dangerous if a piece hit the person operating the machine. The guard completely encloses the the dangerous areas of the CNC.
The CHUCK: This holds the material that is to be shaped. The material must be placed in it very carefully so that when the CNC is working the material is not thrown out at high speed.
The MOTOR: The motor is enclosed inside the machine. This is the part that rotates the chuck at high speed.
The LATHE BED: The base of the machine. Usually a CNC is bolted down so that it cannot move through the vibration of the machine when it is working.
The CUTTING TOOL: This is usually made from high quality steel and it is the part that actually cuts the material to be shaped.
1. Draw a small CNC machine and label the most important parts. 2. List the safety factors that people must be aware of before they operate a CNC or similar machine.