Archive for the ‘Learn CAD’ Category

In this video, we go over the CAD portion of the CNC Process.

In this CNC Basics Video we go over CAD. CAD Stands for Computer Aided Design. During the CAD step we take our initial design an In this CNC Basics Video we go over CAD. CAD Stands for Computer Aided Design. During the CAD step we take our initial design and translate it into the computer. We do this CNC Step so we can change the design, resize it, save it, transfer it to someone else, etc. Recording our CNC Design into CAD gives us flexibility.
During CAD we learn we first design parts, then assemblies, then groups, then machines. We also learn there are different types of CAD Software. 2D, 2.5D and 3D. These types also come in different software packages from inexpensive to expensive. You can spend up to the sky if you want.
The trick is to match the CAD Software Capabilites with your CNC Needs. You don’t need high power 3D Modeling CAD if you make simple parts day in and day out.
Tomorrow’s lesson is CAM. Computer Aided Manufacturing.

CNC Stomp Pad Video 3 – Rhino 3D

In this CNC Video we take the design into Rhino 3D.  We scale it to the size we want and then convert it into a DXF File.  That prepares it for the next stage which is CAM.

CNC Stomp Pad Video 2 – Illustrator Design

In this next video we go over the design of the CNC Stomp Pad.  We use Adobe Illustrator to sketch it out.  We prepare something that a CNC Plasma Cutter could follow.

CNC Stomp Pad Video 1 – Project Intro

Here is the first video in the CNC Stomp Pad video Series.  In this video we outline the project and what we are going to be making.  Check it out!

Introduction to Design
Designing is arguably the most important step to the CNC process.  Why you might ask?  Because it is at the beginning.  This is the planning stage of the process.  If you come up with a bad design, all of your work after this point is lost.  I also think of designing as the planning process.  You need an inventory of what you have to work with before you begin.

Every thing needs some planning to start with.  Whether it is a family vacation or buying a home.  CNC is no different.  You need to think about what you want to accomplish before you ever invest any time or money.  Now I am not saying you need to have a perfect plan.  What I am saying is that you need to at least have a plan.  Believe me I have had many plans and virtually none of them ended up perfect.  What it did do was give me a guide to follow.  A roadmap of sorts.
You also need to know your limitations.  For example, don’t go designing a metal sign if you have a CNC Wood Router and nothing else.  Or, you want to make a 2” thick wood routed sign, but your CNC Wood Router only has 1” clearance.  You will need to know you own personal capabilities and your shop’s capabilities.  Once you know that, you can improve your situation either through training or purchasing other tools.

Where do good design ideas come from?
First, look around.  Take an interest in your environment and all the various objects around you.  Look at how things are built.  Generally, I don’t look at the overall design.  I try to figure out how they build a specific part or area of the design.  For example a unique latching mechanism.
A lot of good design is experience.  Experience comes from failure as many people have said.  The bottom line is you need to try stuff and experiment with ideas.  Pick the ones that are useful and go with them.  Leave the failures on the scrap pile and move on.  Never marry yourself to an idea as being perfect.  Virtually everything can be improved upon.

Know what you want before you build it
When designing it is very important that you know what you want to build.  You don’t need to know every detail, but it helps if you have a general idea.  For example, the item may need to fit inside a certain dimension.  This dimension could be the size of the box used for shipping the item to the customer.  This is a requirement of your design.  Requirements can either be self-imposed or put upon you by someone else.
Another example may be building a piece of art.  You may want to make the piece out of Stainless Steel because it would reflect the sun and hold up in the environment.  Then you find out Stainless Steel is too expensive and that you don’t have the equipment to work with it.  Stainless usually maxes out your equipment. 

You need to have a plan, at least a rough one.  You will need to take inventory of your capabilities and match your design to them.  You will also need to get all requirements for the project before you ever begin.  If you do that, you will not waste extra time redesigning again and again.

What are the limits?
Really, you are the limit.  You brain and its thinking are the limit.  If you can think of it, someone, somewhere can probably build it.  The more you expose your brain to different things and ideas, the more connections it will draw.  This is where your creativity will come from.  You need to feed your brain interesting information and it will spit back some interesting designs.

Part vs. Art
In designing for CNC, there are two different paths.  Art or Part.  By art, I mean a design that may have extra embellishments, curves, features, text, etc.  By part, I mean a square with a hole in it.  Or a triangular gusset.  Art is usually flowing or an image of something.  It could also be a sculpture for example.
When you are designing art, you normally keep a sketchbook with your ideas.  You note them.  They don’t have to be perfect, just roughed out.  Sometimes I cut things out I find interesting and put them in my sketch book.  Things like interesting shapes, interesting images or even a unique way to bolt things together.

When you are designing parts, you are dealing with deadlines and customer requirements.  There are no extra things to personalize or stylize the part.  The part is utilitarian and gets the job done.  This is the majority of what CNC is used for.  This is what various industries use CNC for.

Designing on Paper
Most people scratch out their initial ideas on paper to rough them out.  I like to draw things out in a print, drafting or blueprint format.  This style uses multiple looks and multiple angled drawings to convey what you mean to someone else.  I picked up this style of drawing while working in a manufacturing environment.  Some wood workers will also recognize this style.  Think of a time when you bought “The Plans” to building a birdhouse.

Designing with a Computer
This is what I use next.  Once I have something roughed out, I like to translate it into a computer.  Things are more exact.  You get a feel of the size or how parts fit together.  You also get the benefit of saving your work and coming back to it later.  You can even share your files with others when working on a project.

My Design Computer Setup
A number of people have asked me what my design setup is at home.  Here is what I like to use.  First a powerful computer with plenty of processing power.  Make sure to get as much processing power, RAM and a big hard drive.  Don’t skimp here.  CNC software uses a lot of system resources and you will save time by having a computer that can handle the load. 

Next, buy a dual monitor setup.  You will need a graphics card with a dual output head and two monitors to output to.  Most home users can install this themselves.  Dual monitors keep you focused.  I really like being able to keep my computer screen clean of various design palates that seem to clutter it up.  A dual monitor is perfect for this.

Hobby CNC
Hobbyists get into CNC for many different reasons.  It really has a lot to offer as a hobby.  There are many challenges to it and that is what draws in many people.  This is not something you do just to pass the time.  There is a result in mind.
Some people make it to Hobby CNC through a side door.   They come from areas like Combat Robot and RC Modeling.  There are many small, precise parts in these hobbies, which CNC is perfect for.  There are also many enthusiasts that like to customize things so they need a way to make unique parts that they can’t get anywhere else.

Here are a few elements that have brought people into the CNC Fold:
Electronics – There are many electronic components you can build yourself.  Do you like to solder together power supplies, cooling fans, drivers and processors? CNC would appeal to you.

Design – Do you like to think about things in your mind?  Then conceptualize them into a computer.  Do you have a little inventor inside of you trying to get out?  CNC would appeal to you.
Manufacture – Do you like to make things in a process fashion?  Step by step, process by process.  Do you like to optimize and test and make processes more efficient?  CNC would appeal to you.
End Design – Do you have a result or end design in mind?  This is what happened to me.  I knew where I was.  I knew where I wanted to go.  I then used CNC as a bridge to get there.  If you have an end design in mind that is repetitive, then CNC would appeal to you.
Money – Do you like money?  Boy is that a question.  Many hobbyists get into CNC to make some extra money or start their own business.  Yes, you can make parts and sell them.  Guess what, after you design the part, you never have to do that again.  You can just call up the program and make some more.  Months and years later…forever.  CNC appeals to people who want to make money.
Challenge of Building a Machine – Some people just get bored and want a project to work on.  Building a machine that does something appeals to them.  Think of the Model Builders, Woodworkers, Metal Workers and any other type of builder you know.  CNC appeals to the builders of the world.
The Entire CNC process – I fall strongly into this category.  I started into CNC because of a problem, but stayed because I love the whole process of it.  I like to design things.  I like to build things.  I like to make money.  I like the challenge.  I like the whole enchilada.  That is what I want to share with you.

What personal attributes will help you with CNC?
I get this question a lot.  How do I know if CNC is right for me?  Guess what, I have seen it all.  Many types of people show up in CNC.  Here are some common skills I see often in the field. 

Computers – Do you like working with computers?  If you said yes then that will help you out.  CNC is really computer intensive work on the front end of the process.
Software – Can you learn multiple software packages?  If you said yes you probably have a flexible software mind.  That will come in handy.
Shop Skills – If you have skills in the shop, you will be ok.  It doesn’t really matter if it is metalworking, woodworking or anything else.  Being comfortable getting your hands dirty will help.
Engineering Mind – I usually think of this as a problem-solving mind.  Trying to isolate things and pin them down.  If a problem come up, you test different ways around it.  Keeping track of things will help.
Artistic Mind – Can you imagine things?  Think of the products you create.  Guess what, creating is very important.  Using you mind and thinking of unique possibilities will help.
Crafty Mind – I don’t mean in a devious way, more in a building way.  Can you take things apart and put them together in your head?  Can you see a finished product, and then back track the processes to make it?  You will be well served if you can play with things in your mind.

“Wait, wait, wait,” you might say.  “I don’t possess all these skills.”  You don’t have to.  Having some of these skills will only help you on your quest to learn CNC.  Again, I have seen all types of people get into and succeed in this field.  Your desire to learn and get out there and do it will be the deciding factor.

There are a variety of different levels of knowledge and skill with CNC.  You need to figure out where you fit in to the topic.  When you know your level, your learning on the subject will be much more effective.   

If you are an expert in a subject, you can blow through most subject areas and only pick up what you need.  You can readily see the new ideas proposed because you know the lay of the land.  If you are a newbie, take your time and study intently.  Then go back and re-read the topics again and again.  With each new read you will be able to pick up more and more.  This is very similar to the proverb, “the teacher will appear when the student is ready.”

CNC Knowledge Levels
Newbie:
Hobbyist or student
You need to learn the general process of CNC
You have heard various CNC terms, but don’t know what they mean or how they relate
You might have some end result idea of what you want to do with CNC

Beginner:
You probably know the general process of CNC
You stumble across problems with programs or the machine on a regular basis
You have some learning “battle scars” and could maybe explain some basics to others

 
Intermediate:
You know the process of CNC and have worked through it multiple times
You can see and recognize problems before you ever begin machining
You understand the software you use and all its nuances
You have machined multiple parts out of multiple materials.

Advanced:
You know what “Fanuc, Mazak, Canned Cycles and Conversational Programming” mean
You probably work in a production environment with CNC technology every day
This book is probably not for you

Take a minute to score yourself before we move on.  It will be valuable for you to know what level you are at and what level you are headed to next.
As a generalization this book was written for the Newbie to Intermediate CNC students.  Everyone who works with CNC can probably learn a thing or two, but Advanced CNC users probably know most of these concepts like the back of their hands.

One last note before we get going:
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.

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).

What I used to do…
Before I found design software I was in the stone ages.  I would actually hand lay out a template on a piece of paper.  Then cut it out.  Next, I would tape the design onto a piece of steel and trace around it with a Sharpe Marker.  Finally, I would cut out the piece I wanted.
No matter what, it was never exact.  There would always be something wrong.  Things like wavy lines, gouges and “unique parts” were the norm.  Measurements were never as exact as I would have liked either.  That usually caused some fit-up issues, followed by some grinding.  If you know anything about fabrication, grinding is the enemy of your time.

Why use Design Software?
I knew there had to be a better way so I found some design software to try out.  Yes, it does take some time to learn.  Think about it, like anything else in life, something that is worth it takes some time.  This is also the situation of taking one step backwards to move ten steps forward.

Here are some advantages of using Design Software:
Saved file you can use over and over
Transfer the design to others
Can use exact measurements
Repeatability in design

Here are some disadvantages of using Design Software:
Cost money
Takes time to learn
May not be the quickest way of making something if it is a “One Off”

My Definition of Design Software
If you are an engineer, you will probably consider CAD Software as design software.  That is true.  But what I am talking about here is “Creative” Design Software.  These software packages are used by creative types for print, web design and logo design.  This software is great for creating designs that flow and are artistic in some way.
Design software can be boiled down to what it is good at.  If you want to make a square with a hole in it or a triangular gusset, then CAD type design software works great.  If you want to cut out a Cowboy on a Horse, then “Creative” Design Software is the only way to go.

Here are some examples of work for “Creative” Design Software:
Plasma Art
Router Art
Signs
Engraving