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+ | ====== A Brief Explanation of CNC Machines and How They Work ====== | ||
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+ | For more in-depth info than is covered here, look at the following: | ||
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+ | **[[http:// | ||
+ | //by Mike Lynch, CNC Concepts, Inc.// | ||
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+ | =====CNC basics===== | ||
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+ | To better understand the problems involved to successfully use your Rhino data for a CNC-controlled machining or cutting type operation, you need to understand the CNC process and how it works. | ||
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+ | ====First, a couple of definitions==== | ||
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+ | **[[cncmilling|Here is a summary of the steps required to get a digital model to a CNC milling machine.]]** | ||
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+ | ====CNC controlled machines, general==== | ||
+ | CNC machines can have several axes of movement, and these movements can be either linear or rotary. | ||
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+ | ====Some limitations of CNC controlled machines==== | ||
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+ | Depending on their age and sophistication, | ||
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+ | The speed at which the machine controller can receive and process the incoming data, transmit commands to the drive system, and monitor the machine’s speed and position is critical. | ||
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+ | ====Interpret your 3D and spline data first==== | ||
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+ | A typical problem is how to set up your files and do your CAM programming so that the machine executing your parts will work smoothly and efficiently with the data. Since most CNC controls only understand arcs and lines, any form that is not describable with these entities needs to be converted into something usable. | ||
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+ | Splines can be broken up into a series of line segments, a series of tangent arcs, or a combination of both. You can imagine the first option as a series of chords on your spline, touching the spline on each end and having a certain deviation in the middle. Another way is to convert your spline into a polyline. | ||
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+ | Imagine surfaces as the same kind of spline approximation, | ||
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+ | The size and number of segments are determined by the accuracy required and the method chosen, and will directly influence the execution. | ||
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+ | ====Common conventions used in describing CNC procedures==== | ||
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+ | Your project can be: | ||
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+ | **2 Axis** if all the cutting takes place in the same plane. | ||
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+ | **2.5 Axis** if all the cutting takes place entirely in planes parallel to the principal plane but not necessarily at the same height or depth. | ||
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+ | A subset of the above is that the machine can interpolate any 2 axes together simultaneously, | ||
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+ | **3 Axis** if your cutting requires simultaneous controlled movement of the X,Y,Z axes, which most free-form surfaces require. | ||
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+ | **4 axis** if it includes the above plus 1 rotary axis movement. | ||
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+ | **5 axis** if it includes the above plus 2 rotary axis movements. | ||
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+ | --MSH 28.10.07 | ||
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