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Metal Machining...CNC and CAD-CAM

Howdy racers and race fans! I'm Jerry Gordon (Maverick on the net) Crew Chief for Al Miles and the FFR PRO DRAGSTER race team out of Edmonton Alberta Canada. I have been riding and racing motorcycles since I was 11 years old. When I started racing Fred Flintstone was my crew chief. Over a 25 year period I have built and raced a 890cc RC Eng. Honda Street bike, a double engine 2200cc RC Eng. Honda, a Kawasaki 1200cc Pro Stock, a blown and injected Top Fuel 1100cc Honda, a Kawasaki 1200cc turbo NOS Funny Bike, a 1385cc injected Nitro Suzuki, plus a bunch of road race stuff in the late 70ds.Over the years I have fabricated about 25 complete drag racing chassis complete with motor plates and some body work. I was the fastest man in Canada for over 10 years and held the record for the longest wheel stand with a Honda CBX. I was the first man in Canada to run a nitro-powered motorcycle and learned a lot of what I know about nitro from Bernie Fedderly one of Force's crew chiefs.

Anyway...enough about the past. Let's talk about the future. The future of machining components for all types of racing machines 2 or 4 wheel, straight line or roundy round. The future is CNC machining coupled with CAD CAM systems. CNC stands for computer numerical control. Basically this means that the machine movements are controlled by a code of letters and numbers. The letters and numbers in the code tell the machine to perform a specific function, for example drill a hole. Then another set of numbers with an X,Y,Z letter in front tell the machine where to drill that hole and how deep. If you were to take a map of your hometown and lay it on the table of a milling machine then give the machine the address of your house the machine would go to your house and drill a hole right in the middle of it. That code would look something like this.

T1 M6
M3 S1500
M8
G81 X-0.418 Y-1.765 Z-0.113 R0.1 F1.5
T1 (Tool number for the drill)
M6 (change the tool)
M3 (turn the spindle on)
S1500 (RPM for the spindle)
M8 (turn the coolant on)
G81 (drill a hole)
X-0.418 Y-1.765 (move the table to this position)
Z-1.00 (drill the hole 1inch deep)
F1.5 (feed the drill into the material at 1.5 inches per minute)
R0.1 (return the drill to .100 above the part)

This type of code is called G code and about 90 percent of the CNC machines in the world use it.

Now lets move on to CAD CAM programs. CAD stands for Computer Aided Design or Drafting.

Basically this is a computer program that allows you via a keyboard and mouse to draw on your computer screen. The nice thing about this type of drafting is that you never need a protractor or an eraser. This system is great for doing things like conceptual design and engineering. Parts and components can be drawn to scale on the screen and the easily multiplied, or manipulated into completed assembles. Nowadays with 3D graphics and solid modeling one can see exactly what a part or assemble will look and fit like before it is ever made.

CAM stands for Computer Aided Machining. This computer program links to the CAD program and is really the heart and soul of the system. What it does is allows you to click on different elements of you part drawing on the CAD screen and apply tool paths (machine moves) to your drawing.

For example drilling holes or machining the shape of your part. Then you can do a graphic animation of what the machine will cut and see what your part will look like. As you are doing this, the program is writing the G Code that the machine understands in the background. The code produced may be thousands of lines long but the computer generates it in a mater of seconds. This code can then be transferred to the machine on the shop floor and the parts can be made.

So as you can see the basic principles of CNC CAD CAM are fairly simple. CNC machines have been around for many years but it was not until the development of CAD CAM software that they became practical for doing one off or small run jobs. In the early days of CNC the operator had to write the code line by line on the computer in the machine. This was a long and arduous process and was not very practical for complex parts or small runs.

So now your thinking well what good is that to me as the average racer? From what I have seen over the years is that the average racer always has some part or gismo that he or she would like to make or needs to be remade because you cant get it any more. Here's the deal the largest part in most cases, of producing CNC parts is the drawing of that part. If the part is drawn accurately and to scale then it is a relatively easy process to have a local CNC machine shop with a CAD CAM system program the code and make the part.

CAD systems are relatively inexpensive to purchase and fairly easy to learn. CAD CAM systems on the other hand cost thousands of dollars and require a good general knowledge of machining.

There is currently a post running on the stipbike.com bulletin board under V-Twin Racing called CAD CAM if you are interested come over and have a look. There should be some very interesting tips and conversations.

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