A CNC Programming Tutorial is necessary if one is going to properly use a computational numeric control (CNC) milling machine or auto lathe.
Why is a CNC Programming Handbook Necessary?
As the technology for milling and lathing machines has advanced, using these machines has become more and more complicated. With the switch to computational numeric control machines (those machines run by computer that allow for intricate precision work) it has become increasingly difficult for one person to memorize all the different functions that are possible with a CNC machine. Instead of trying to memorize the myriad different functions that CNC machines are capable of, CNC Programming Tutorials put all the information needed to work these machines in one convenient place.
To this end, CNC Programming Handbooks have been created to enable those using CNC machines to program them for whatever function is required.

What is in a CNC Programming Handbook?
A CNC Programming Handbook is, basically, a CNC Programming Tutorial on how to program your machine to handle any number of different functions. From tips on program development to useful information on setting up your machine to notes on tooling selection and machining data, a CNC Programming Handbook can give you detailed instructions on how to program CNC machines to follow your instructions.
Most Handbooks include detailed information on program development. Some of this information is general programming advice, while some is specific to the particular kind of machine or to the function being performed. Also basic in all handbooks is information on setting up the machines so that they can run as specified as well as more detailed information regarding specific functions.
Some of the functions covered in most CNC Programming Handbooks includes tips on how to calculate contour points; techniques for using cutter radius offset; advice on part reversal in milling; information on tool length offset adjustments; block skip applications; polar coordinates, information on how to bore and turn in depth; descriptions and advice on programming tapers; techniques for grooving, threading; advice on practical thread milling; what to do with four axis lathes; how to work with pallet changers and programming cams as well as introduction to macros.
Types of CNC Tutorials and CNC Handbooks
While there are some types of CNC handbooks, such as “The CNC Cookbook: An Introduction to the Creation and Operation of Computer Controlled Mills, Router Tables, Lathes, and More” by E. Hess that contain a good deal of detailed information on the various types of CNC machines in addition to basic information for programming them, there are also tutorials such as those contained in the “CNC Programming Handbook, Third Edition” by Peter Smid that contain deeply detailed information on specific programming and machine functions. There are even handbooks such as the “CNC Machining Handbook: Building, Programming, and Implementation” by Alan Overby that not only contain information on programming CNC machines and implementing specific projects, but which also cover information on how to build a CNC machine from a kit or from scratch.
Regardless of whether you are using a CNC machine for hobby work, or whether you are attempting to understand the workings of an industrial-grade machine, there are CNC tutorials and CNC handbooks available for all your needs.