CNC Basics
What is CNC?
CNC stands for computer numerical control. This is a large machine that moves a high speed router head or a laser to machine parts from plywood.
Why is CNC technology so important?
CNC cutting brings the computer age into the production shop. It wasn't long ago that machines like this were called robots. They are capable of cutting parts far more accurately and much faster than a human.
Why did Chesapeake Light Craft invest in CNC technology?
We found that by using CNC cutting we could reduce costs and lower the price of our kits. At the same time the quality of the parts improved dramatically. In addition, we could now take files right from the design computer and cut parts for prototypes; development time for new models was greatly reduced.
Are machined parts the same as CNC cut parts?
It depends. Some companies claim their parts are "machined to tolerances of .004"" for example, implying that they are CNC cut. But the parts are really cut using a router table and a template. This is the system that we used prior to acquiring our CNC machine and we can tell you that there is no comparison in precision or quality. Always ask if a part or kit is CNC cut---and if the company subcontracts their work or owns their own machine.
Is laser cutting or router cutting better?
For boat kits we believe that router heads are superior. Router heads allow 3-dimensional cutting of scarfs, rabbets, and bevels while lasers can't cut in 3-D. Router heads leave a smooth even edge, while laser cutting leaves a black burned edge - soot gets everywhere when you handle parts. There is no difference in accuracy or precision - that depends on the machine, not the head that's attached to it.
Maximum speed is about 1000" per minute, while maximum cutting thickness is about 6 ".
What sort of bits cut the wood?
They are special solid carbide spiral bits turning at about 20,000 rpm in a 13HP motor. Even so, the router bits wear out every 4 - 6 hours and cost $36 each to replace.
