Ivan Irons asked:


When I went through college I learned how to read prints and draft. We had a bag of physical tools that we purchased and hauled around campus. T-Squares, French Curves, compasses, pencils and erasers filled this bag. Then you had a pad of drafting paper and a drafting desk. You would pin or tape the paper down and begin drawing or drafting.

Drafting paper has a grid to help keep you aligned as you began you design. In CAD, there is a grid you snap to, or guides to keep you straight. We had hard plastic templates to draw curves. CAD has numerous tools to draw curves and lines. We had calculators to figure out distances and ratios. CAD does this automatically.

Overall, you can view CAD as replacing Drafting. CAD moved the same type of process into a more flexible and efficient environment. CAD has also helped out with networking of designs. Different designers and engineers can work on the same assembly in different parts at the same time. This team effort really moves the overall process along much faster.

However, as far as print reading goes, that is about the same as it was before. Drafting outputs prints and CAD outputs prints. A human still needs to be able to read them and make sense of them. A plus with CAD is that it is much more standardized and clear. Many times before, prints were unique to their maker. Similar to handwriting, you could not always figure out what the engineer wanted to convey to you. CAD cleans all that up.

CAD is the way we work today. I would be very surprised if you could come across a shop that has hand drawn prints. It just isn’t practical. Precision and accurate prints are the way manufacturing increases efficiency.

Ivan Irons asked:


There are multiple CAD programs available for design. Generally people become familiar with one and stick with it. As far as selecting the right one, my advice is this. Most software companies have a free trial. Thirty-day trials are common. Take advantage of these trial periods and test the software out. Then at the end, decide if you want to try another software or stick with your best one. I would advise you try out at least three different packages.

The one you select will probably have to do with you liking the interface or finding it intuitive. Keep in mind it may work for you now. A simple to use and understand interface probably has some limitations for your designs. The very best programs are complex with many tools that give you the most control. I have found that I start with a simple program and outgrow it. At some point I move up to the next level of software. This usually means a higher price as well.

Types of CAD

There are different types of CAD out there. These are the ones I deal with from time to time. 2D CAD, 2.5D CAD, and 3D CAD. Here are some quick explanations of each type.

2D CAD

2D CAD is generally on the low end of CAD software packages. 2D CAD is most often vector based. The design consists on the X and Y-axis only. The designs are made up of lines, circles, ovals, slots, curves, etc. There is no “depth” to the design. Only the outline of the part is visible, to put it in a different way.

2.5D CAD

All of the same descriptions above apply, but the design is prismatic. By that I mean it has the depth of the material. There are Z levels, but they are on singular planes.

3D CAD

3D CAD is on the high end of CAD software packages. 3D CAD can be solid based, wire frame based or nurbs based. The design consists on the X, Y and Z-axis. The designs are made up of lines, circles, ovals, slots, curves, etc, but can also include Spheres, Pyramids, Torrids, Cubes, etc. There is depth to the design. The design can be rotated around 360 degrees. The design is an accurate description of what the part would look like if produced in the real world.

Paul Disley asked:


The development of computer numeric controlled (CNC) routing, using affordable personal computers has already begun to revolutionise all aspects of the woodworking industry. In so doing it has created new opportunities for large and small businesses as well as for individual craftsmen.

CNC is a technique whereby the movement of a router head is controlled by instructions from a computer. These instructions come from a computer program or list that the user keys into the CNC 860 console or into a computer as ISO standard commands called ‘G’ codes.As an example, the code G01 X100 Y100, instructs the head to move in a straight line to a point horizontally and vertically 100mm away from its starting position.

The CNC 860 The Trend CNC package is based around the Elu/DeWalt CNC 860 Machining Centre, which has a machining area of 860mm x 860mm x 90mm. These dimensions relate to the three axes, X,Y and Z (width, length and height). Each axis is served by a separate stepper motor, controlling the movement of the routing head. Two head options are offered: a modified portable router or a continuously rated, high cycle motor, that provides improved performance for intensive machining applications.

Programming directly in G-codes through the console can be time consuming. To assist the operator, a PC software application called CNCTalk is included with the machine. This is a basic computer aided design (CAD) application which runs under DOS, the original PC operating system before Windows. It is useful for intermediate applications like cutting out irregular shapes. However, to gain the maximum versatility from the CNC 860,Trend’s Open Sign System Software for Windows is the most effective solution.

OSS consists of two separate software applications: OSS Draw which provides the drawing tools to create any shape or sign, and OSS Work which handles all the routing and tooling-related parameters like depth and offset. Graphical simulations are shown for all tool parameters enabling the user to perfect a design before routing any material.

Sign-writing As an example of how these products work together, the method of producing a simple sign is shown, incorporating two different lettering styles and a graphical logo. Having launched OSS Draw, the first step is to draw a box or boarder on the screen to indicate the overall area of the work. This can be either a simple rectangular boarder or a more decorative one. This border then needs to have a depth assigned to it. This is done by using colours to define the depth of each area.

The logo is then created using the drawing tools within OSS Draw. The words are keyed in using the text function. Again, colours are assigned to each area to produce a graphical representation of how the finished sign will look. The next task is to define the routing parameters. In the example, the red and blue areas of the logo and the lettering have been assigned a depth of 5mm and the green area assigned a depth of zero. The same dialogue box lets you specify whether a letter or object is engraved or routed through the material. The cutter profile that will be used can now be defined. With lettering, particularly serifed fonts, the cutter used needs to have a small diameter, perhaps 3mm. However, to achieve a 5mm cutting depth this will have to be routed in several passes.

A simulation of the cutting path is now drawn on screen. Having then created a G-code file of the sign ready for the CNC 860 to cut, the file is downloaded to the CNC 860. The design can now be routed, the material being held on the bed by an adaptable clamping mechanism. From the simulation, the path that the tool will take is known allowing a datum point to be set using the zero key on the console, and the program 8 INProfile is run using the start key. This type of routing operation takes around 20 minutes to complete and requires no further involvement by the machine operator. Other accessories Sign-writing is just one of the many complex and wide ranging routing operations that can be carried out using the OSS and CNC 860 package. OSS also has a range of tools for drawing component shapes and profiles directly or with an electronic sketchpad (graphics tablet). Vacuum Clamping To reduce the through-put time for this kind of operation, the CNC 860 can also be used with a vacuum bed. Trend offer a complete range of affordable vacuum pumps and jigmaking accessories to enable all CNC users to produce a highly automated production system to suit their own specific requirements.

Ivan Irons asked:


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

Every CNC machine has quirks that you need to learn. Every CNC machine has a different working envelope. Every CNC machine is just a little bit different then the rest of them. It is in your best interest to learn your machine before you put it to work.

Generally, with a CNC machine, we are machining something. While machining, “chips” are being thrown off. Sometimes at a very rapid speed. Here is where safety glasses, face shields and material barriers come into play. Use them! The machine doesn’t know you are standing there. In the words of every boxing ref before a match, “protect yourself at all times!”

Every CNC machine has quirks that you need to learn. Every CNC machine has a different working envelope. Every CNC machine is just a little bit different then the rest of them. It is in your best interest to learn your machine before you put it to work.

Ivan Irons asked:


CAD Design Process

When designing something complex in CAD you will find there is a bit of a process. First you design parts. Then you build the parts into Sub-Assemblies. Next you build sub-assemblies into Groups. Then you build the groups into the machine. It is a logical pyramid process. You can also think of it like a file structure inside of a computer.

Designing Parts

Parts are your building blocks. Without this level, nothing could be produced. The part level breaks the entire “thing” down to its simplest form. You also manufacture at the part level. You make parts, and then assemble them into other things. Parts are generally made out of raw materials.

Think of a differential on the rear axel of a car. The differential is made up of gears and a housing. Each of these are parts of the differential and the differential is the assembly of these parts.

Designing Sub Assemblies

Sub Assemblies are the next level up and I am guessing you are getting the idea. You first design parts, then put them together into sub assemblies. In the car example above the differential is a sub assembly in the axel “Group” of the car. Sub Assemblies are put together to form groups.

Designing Groups

Moving up the design chain, groups are usually things you can identify with. It could be a door, engine, transmission, or cooling package on a car. Above we used the example of an Axle as a Group. Groups are put together into machines. Our example is a car, which is at the machine level.

Designing the Machine

Finally, the top level of all your designing, the machine. The machine could be built for the end user or be sold to another manufacturer. That manufacturer could use your “machine” as a sub assembly or group. You can see all this is just a matter of viewpoint. You can consider just about anything a sub assembly, group or final machine. It is all just semantics and what you are using the item for.

Ivan Irons asked:


Quick Explanation of the Process

This is how I view CNC. I break it down into simple steps that I can remember. Now, they all interact, but it is good to keep them in boxes for simplicity sake. I also like to keep them in a logical, progression type order. Here they are: Design, CAD, CAM, Control and Machine.

Today you are going on a journey. You are going to learn about the basics of CNC. I hope you are as excited as I am about this topic.

I have been using CNC equipment in my home shop for six years now. The technology gets better and better every year.

The software gets better every year. At one time large companies could only afford this technology. Now there are hundreds of thousands of these machines working in garages like yours and mine.

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

Design - thinking and planning what you want to build

CAD - translating it into the computer

CAM - converting it into machine language

Controlling - directing your machine’s motion

Machining - building the part to specifications

These five elements are really the building blocks to a CNC project. As you see them above, that is generally the order people associate them in. For example, you can’t control until you have a design. You can’t use your CAM software before your CAD software. One of the main things you need to address is how these elements interact with each other.

Right now this may seem confusing. Over time, it will seem very basic. The more you use these elements with one another, the more their order will become second nature.

Note: The A-axis is the rotational axis. Why is it called that? I don’t know. It is also sometimes called the B-axis. I have even heard it called the W-axis. A-axis is the rotational axis around the X-axis. B-axis is the rotational axis around the Y-axis.

Buying a completed CNC Machine

If you purchase a CNC machine outright, it will have a machine controller as part of the package. Everyone does it a bit different though. Some try to make it a black box that only they can fix. Other use commonly used components so you could repair it if need be. You will just have to ask the manufacturer and see what they say. My experience says they usually tell you that it uses common components that you can get anywhere if needed. If something goes wrong, it seems you can only get the part from them. You will have to decide.

Internal Machine Controller Parts

There are many different electrical components that go into a machine controller. I won’t pretend that I am an expert on this. Actually, this is one of the components I buy pre-made so I don’t have to do it. If you are an electronics junkie you could build your own. I know where my skills are at and it isn’t in assembling and understanding electronics.

Here is what I know about the guts of a controller. There will be drivers. One for each axis.

Ivan Irons asked:


CAD stands for Computer Aided Design or Computer Aided Drafting. CAD was developed in the early 60s. Today it is the premier way to design, develop and optimized products. People use CAD every day to design virtually every product you see. Generally, designers use CAD to design a product, and then produce prints to manufacture that product. A print is a picture of a part or assembly that is very exact. It includes the dimensions and a parts list used to manufacture a product.

CAD is the use of computer based software packages that assist engineers, architects and other design professionals in their designs. CAD is the part of the main designing process and involves both software and sometimes hardware. Current software packages range from 2D vector based drafting systems to 3D solid and surface modelers.

Computer Aided Drafting software packages can generally be broken into two groups. The groups are 2-D drafting packages or 3-D drafting packages. Most all software packages are moving to 3-D design. 3-D design is really the next generation of CAD. Utilizing 3-D design, engineers can make a model of their product. They can then look over this model for any apparent defects before it is ever made.

CAD is used to design, develop and optimize products. CAD is mainly used for the engineering of models and/or drawings of components. It is also used throughout the engineering process from concept to design of products. These products can be used by end consumers or used in other products. For example, you can design a bolt in CAD, and then use it in a Sub-Assembly in a planetary, which is a part of an earth-moving machine. CAD is also used in the design of tools and machinery. Finally, it is used in the design of all types of buildings from sheds to shopping malls.

Ivan Irons asked:


The Control Computer generally resides in the shop somewhere near the CNC machine it is controlling. Control Computers don’t have to be the top of the line, every bell and whistle type of computer. These are the workhorses. Save your money for a good design computer. You will save much more time having a fast computer for your designing.

A control computer doesn’t have to be that powerful for a few good reasons. It doesn’t have the workload. It takes G-Code and turns it into signals that it transmits to the Machine Controller. Turning G-Code into signals is not that labor intensive for a computer.

I have used multiple types of control computers. Everything from a 486 DOS running “$30 special” to a modern Dell with Windows XP. I have yet to try one with Vista. I will keep you posted. Generally I like to find a good used computer for a couple hundred bucks, wipe the hard drive and only load the control software onto the machine. That way you know what you have.

There is another good reason you don’t want to spend a lot of money here. This computer will usually be located in the shop. Dirt will be located in your shop. Using logic here, dirt will be located in your computer. If the computer does go belly up, you aren’t out your children’s college tuition.

Here is my strategy in a nutshell for Control Computers. The dirtier the job, the less money I spend on the computer. My plasma cutting computers are bought in the $40 range. They eat a lot of dust and dirt. I blow them out frequently. My wood routing computers are in the $100 dollar range. My milling machine computers usually are in the $200 range. Truth be told, they all last a very long time if you keep dirt, dust and plasma smoke out of them.

How is the CNC Control Computer used?

The control computer has the control software loaded on it. You start up the control software then load up the CNC Program you created. When you do this, the G-Code will be visible and ready to go. Once you prep your CNC Machine and zero it out, you can begin your “cycle.” A cycle is usually completing one CNC Program, which is a machining sequence. You will also hear the term “Cycle Time” on the professional side of CNC a lot more. The quicker you can get the cycle time, the more parts you can make. And yes, that translates to more money.

Back in the good old days of Home CNC, everything was transferred on a disk. Now I have seen people include their Control Computers on their home computer network and transfer the files needed wirelessly. At a very minimum, get a good jump drive and transfer things back and forth that way.

CNC has become a very popular hobby and more and more people are starting to hop on the band wagon of CNC. Its a fun hobby and easy to do from your very own home with just a little elbow grease and creative mind.