Archive for the ‘CNC Forums’ Category

CAD (Computer-aided design)
Geometry authoring tool that involves software and sometimes special-purpose hardware. Current packages range from 2D vector based drafting systems to 3D solid and surface modellers.

CAM (Computer-aided manufacturing)
Considered as an NC programming tool wherein 3D models of components generated in CAD software are used to generate CNC code to drive numerical controlled machine tools

CNC (computer numerical control)
Refers specifically to a computer "controller" that reads G-code instructions and drives the machine tool.

CAD/CAM part programming
The computer calculation and creation of a toolpath based on part geometry information created in CAD.

Canned cycle
A predetermined machining sequence used to simplify programming.

Data
Information processed as the basis for calculations.

Database
Computer storage that holds data and is searchable

Detail Drawing
A drawing of a part giving a complete and exact description of its form, dimensions, and construction

Dimension
The desired measurement of a part

Documentation
A CAD process in which a part design is converted to a computer file or hard copy for reference and storage purposes.

Drawing Exchange Format
DXF. A standard storage format for personal computer-based CAD/CAM platforms

Driver
That portion of the electronic package that receives the stepping sequence from the translator and provides the switching of the windings in the stepper motor.

G-Code
Common name for the programming language that controls NC and CNC machine tools

Geometric Modeling
A modeling process in which a designer creates lines and text that represents the shape of a desired part. Geometric modeling is the first step in CAD.

Geometry
The measurement, properties, and relationships of the lines and points of an object that make up its shape

M Code
A code used to signal an action from a miscellaneous group of commands. M codes change cutting tools, turn on or turn off the coolant, spindle, or work piece clamps, etc.

Machine Control Data
Manufacturing instructions defined in CAM and enacted on a CNC machine.

Machine Control Unit
A small, powerful computer that controls and operates a CNC machine

Machine Tool
Powered mechanical device, typically used to fabricate metal components of machines by machining

Machining
The selective removal of metal or material

Numerical Control
The use of computers and special program instructions to execute the sequence of machining operations to make a part.

Part Program
A series of numerical instructions used by a CNC machine to perform the necessary sequence of operations to machine a specific work piece.

Personal Computer
PC. A computer designed for an individual user and commercial software. Desktops, laptops, and notebook computers are PCs.

Plotter
A large printer used to print blueprints. These output devices support vector graphics, unlike dot matrix and laser printers.

Post Processor
A software link in the CAD/CAM chain that communicates instructions from CAM to a CNC machine

Preliminary Blueprint
A design representing the rough dimensions of a specific part

Primitives or Primitive
Basic shapes such as cubes, spheres, cylinders, blocks, and cones that are combined in solid modeling to create a model of a part.

Prototype
The original test model of a part

Raster Image
A form of graphics in which closely spaced rows of dots form an image on a computer screen. Also known as bit-mapped graphics.

Ramping
The process of controlling the pulse frequency to accelerate or decelerate a stepper motor. Ramping increases the ability to drive larger loads at greater speeds by slowing the first series of pulses allowing the motor to overcome inertial loads and reduces overshooting by slowing the motor down more gradually than an unramped motor.

Scanner
A computer device that converts hard copy drawings into digital form

Software
The coded instructions, formulas, and operations that structure the actions of a computer

Solid Modeling
A type of geometric modeling based on solids in which all visible surfaces of a part are shown. In addition, solid modeling describes interior volume, mass, and weight.

Sub-Program
Acting as a part programming shortcut, a part program sequence that is called on as needed. Also called a subroutine.

Surface Modeling
A type of geometric modeling based on geometry only, in which all visible surfaces of a part are shown regardless of volume definition.

Step Angle
The angular increment the motor shaft will turn each time the windings (coils) are energized. The angle is specified in degrees. For a 200 step per revolution motor the step angle will be 1.8 degrees.

Step per revolution
The total number of steps to rotate the motor shaft 360 degrees. For CNC, 200 or 400 steps per revolution are usually used.

Stepper motor
A device that translates electrical pulses into precise mechanical movement. The output shaft may deliver rotary or linear motion.

Title Block
A portion of a blueprint that contains information such as the company name, part name, part number, designer, scale, and material.

Tolerance
A blueprint specification indicating an unwanted but acceptable deviation from a given dimension

Toolpath
The series of coordinate positions that determine the movement of a tool during a machining operation.

Translator
An electronic device that converts pulses into the correct switching sequence, which will operate the motor one step for each pulse received.

Unipolar
A bifilar wound motor. The current flows only in one direction through each winding. Normally there are two winding per bobbin and eight bobbins per motor. Usually is a 5, 6 or eight wire motor. One or more common leads are used per winding. Has less torque than a bipolar stepper motor but is simpler to drive. Bipolar stepper motor- just two windings. The electronic controls reverse the current alternately between the coils. This motor has more torque but requires more electronic controls.

Vector Graphics
A form of graphics that uses geometric formulas to represent images. Vector graphic images are more easily manipulated than raster graphics when dealing with CNC.

Wire Frame Modeling
A type of geometric modeling in which the edges of a part are represented by solid lines

Working Drawing
A drawing of a part providing data for manufacturing

X-Axis
An axis that is left or right. All movement left of a zero point is minus (-X), all movement right of the zero point is plus (+X).

Y-axis
An axis that is at right angles to the X-axis and intersect the zero point of the X-axis. All movement further away from the zero point is plus (+Y). All movement closer than the zero point is minus (-Y).

Z-axis
An axis that is vertically perpendicular to the X-Y zero point. All movement above the zero point is positive (+Z) while all movement below the zero point is (-Z).

        CNC as a hobby has really seen a huge growth spurt over the last 8 years.  I think I stepped into it about two years after it started cooking in the late 90s.  When I jumped in there were a few CNC Groups going already and about three different CNC Plasma Tables available at the hobby level.  I don’t know where the other machine types were at the time because I came in through the plasma path.  I would guess they were further behind as CNC Plasma Cutters was one of the first areas of CNC to take off in the Hobby arena.

        Most of the growth I would attribute to the Internet.  Groups formed, ideas were shared.  Feedback was given.  People started making “chips” and didn’t look back.  The Internet brought a very expensive technology into garages across the country.  When I built my $4000 CNC Plasma Table a hobbyist class machine was around $10,000 and a commercial machine was $100,000 to as high as you wanted to go.

Here is the table of contents to the book I recently wrote about CNC Basics.  The book’s title is "Learn CNC Secrets."

Learn CNC Secrets Table of Contents

CNC Safety. 9

A few ideas to keep you safe in the shop: 10

Foreword. 11

CNC Knowledge Levels    11

One last note before we get going: 12

CNC Intro. 13

Questions, Questions and a few more Questions. 13

My CNC Story    13

My Initial Thoughts on CNC        14

Little Did I know             15

Other things I had to learn along the way: 15

So, where am I at today?    16

CNC Machines I own today:  16

CNC Hobby Growth Story    17

Why do people get into CNC?    17

Production CNC – Professional CNC – Manufacturing CNC. 18

Here are a few jobs on the professional side of the house: 18

Hobby CNC     18

Here are a few elements that have brought people into the CNC Fold:  19

What personal attributes will help you with CNC?. 20

CNC Process Overview: 22

Quick Explanation of the Process. 22

There are basically five elements to a CNC Project that you need to know:  22

Design    23

Here are some important elements of design that need to be answered:  23

CAD     25

3-D Design    25

Here are some examples of 3-D drafting/design software: 25

2-D Design    25

Here are some examples of 2-D drafting/design software: 26

CAM      26

Here are some examples of CAM software: 26

Using CAM Software    27

Here is an example of some G-Code: 27

Control  27

Here is a brief description of the two types of motors generally used in CNC:  28

Machine Controllers    29

Machining    30

Here is a list of common tooling: 31

CNC Process Conclusion    32

The five things to master with CNC are: 32

Design. 33

Introduction to Design    33

Where do good design ideas come from?. 33

Know what you want before you build it 34

What are the limits?    34

Part vs. Art   35

Designing on Paper   35

Designing with a Computer   35

My Design Computer Setup    36

Design Software. 37

What I used to do                     37

Why use Design Software?    37

Here are some advantages of using Design Software: 37

Here are some disadvantages of using Design Software: 37

My Definition of Design Software  38

Here are some examples of work for “Creative” Design 38

Commonly used Creative Design Software. 40

What is your Vector, Victor?    40

Vector Images:  41

Raster Images:  41

Raster to Vector Software    42

File Types You Will Deal With    42

Examples of Different File Types  43

What do I really need to know?    44

CAD. 45

What is CAD?    45

Print Reading and Drafting    46

How do I translate my design into the computer?. 48

Different Design Views    48

The main print or design views are: 48

Here are some photo examples of the different design views: 49

Tools in CAD     51

How do I choose the right CAD program for me?. 53

Types of CAD     53

2D CAD     53

2.5D CAD     54

3D CAD     54

2D, 2.5D and 3D Photo Examples  54

CAD Design Process    56

Designing Parts    56

Designing Sub Assemblies    57

Designing Groups    57

Designing the Machine    57

FMEA Analysis?  What?    58

CAD Software Price Points    59

Hobby CAD Software    59

Professional CAD Software    59

Examples of Commercial CAD Software Programs. 59

What is CAD/CAM?    60

CAD/CAM Article    60

CAM.. 64

What is CAM?    64

How do I pick a CAM program?    65

The different types of CAM Software. 65

Here are the most common types of CAM Software. 66

What are tool paths and how do you create them?. 66

Process of CAM      67

Here are the CAM Steps:  67

Define Material  68

Define Stock Size    68

Define Coordinates    69

Define Tool  70

Define Feeds and Speeds    70

Simulate Machining    72

Tool Paths    73

Post Process    75

So what does CAM Software cost?. 76

Hobby CAM Software    76

Professional CAM Software    76

CAM Software Photos:  77

CAM Programs    78

Art CAM Programs    78

Art CAM Program Examples    79

Machining Simulators    79

CNC Simulator Examples:  79

G-Code. 80

What is G-Code?    80

You will see many variations of the G-Code name like: 80

Are there other “Codes?”    80

Here are some examples of G-Codes. 81

Why does G-Code Change?    81

What is an M-Code?    82

G-Code Example    82

2” Square G-Code    84

Do I need to be a G-Code Expert?. 84

Post Processing??? – Now you have me worried.  With all the variations in G-Codes and M-Codes, how will I ever keep it straight?… 85

Here are some screen shots of lists of post processors that you can select in your CAM Program       86

Controlling. 88

Definition    88

Control Computer   88

How is the Control Computer used?. 89

CNC Control Software    89

Quick List of control software    90

Machine Controllers    91

Here are some example controller prices. 92

Prices    92

Buying a completed CNC Machine. 93

Here are some examples of some Machine Controllers. 94

Internal Machine Controller Parts. 97

Control Pendants    98

Photos of Pendants    99

Machining. 101

Machining Overview      101

Machining    101

Here are a few of them:  101

Different types of machining    103

Here are a few examples:  103

Chips?    105

Different Sources of Tooling:  106

Photos of Different Types of CNC Machines: 107

Keeping your shop clean    115

Here are some examples:  115

Tool Offset   116

Zeroing the machine out   117

The final “Part”    117

CNC Mainstream.. 120

How do you know we hit the mainstream?. 120

End Results of CNC. 121

CNC Glossary. 126

 

From time to time I will get an email from an expert telling me this or that is not perfectly, technically correct.  Usually I agree with them.  What I have tried to present is how I learned CNC and how I made this stuff work in my mind.  Think of it as a Layman’s Guide to CNC vs. a PHD Doctoral Thesis with years of Data Collection and Analysis on the topic.  My point is always to teach, not gain recognition in scholarly journals.