Teaching CNC with the Key Concepts approach - part one

Part one - Introducing the key concepts approach

It is truly amazing how much a Human Being can learn, even when the learning environment is not at its most optimum. Aptitude, of course, has a lot to do with learning. A student with a high degree of aptitude will pick things up quickly, even from a poor instructor. Conversely, instructor with a high degree of aptitude will be able to get through to just about any student.


One constant goal when preparing/improving a curriculum is to maximize the potential for learning, especially for students that don't have the highest aptitude. In most cases, you want to target your presentations to the lowest level of student that will be attending your class. While bright students may pick things up very quickly, you must at least be prepared to work with students that do not have a high degree of aptitude.


Your general approach to teaching will have a big impact on how universal your course appeal will be in this regard. Without a well planned approach, your presentations will be like a ship drifting at sea. They may have meaning, but will never go anywhere.


All students need a light at the end of the tunnel. They need to know where they stand as they go through your course. In part one of this article, we introduce a proven method for teaching CNC courses that we call the key concepts approach. This can be applied to just about any form of CNC machine tool. Indeed it can be applied to any teaching curriculum. In upcoming issues of The Optional Stop, we'll show how the specific key concepts related to a CNC programming curriculum.


The key concepts approach is relatively simple to understand and implement. It involves determining the most important principles that are related to your curriculum and categorizing all presentations and learning activities for the course accordingly. We call each important principle a key concept.


Each key concept should be broad enough to minimize the number of new general ideas a student must master in order to successfully complete your course. We recommend having no more than ten key concepts for a given class. If you come up with more, you're probably not keeping them broad enough.


An example

Here is an example of how we've applied the key concepts approach to CNC programming. With our key concepts approach (the same method we use in our CNC teaching curriculums), there are six key concepts related to G-code level (manual) programming. They include:

  1. Know your machine from a programmer's viewpoint

  2. Prepare to write programs

  3. Understand the motion types you have available

  4. Understand the compensation types that minimize tooling problems

  5. Format programs using a strict structure

  6. Know the special features that can minimize programming time and effort

Think of any topic related to manual programming. It's going to fit nicely into one of these key concepts. Axis direction? That's part of key concept number one. Tool length compensation? That's part of key concept number four. Canned cycles? That's in key concept number six. Circular motion? That's in key concept number two.


Remember, if you come up with a topic that doesn't fit into one of you're key concepts, you either don't have enough key concepts, or they are not broad enough. As stated, the goal is to minimize the number of new things a student must learn (staying pretty broad) without becoming so general that a given key concept will take too long to present.


These same key concepts can be applied to any form of CNC machine tool. This will be especially helpful to students and instructors that are working with multiple machine types. Consider, for example, the various compensation types. With machining centers they include tool length and cutter radius compensation. With turning centers, they include wear offsets and tool nose radius compensation. While specific presentations will be dramatically different based upon machine type, the general reasoning for them is consistent from machine to machine.


It is best if you can begin each key concept by relating the general mentality behind the key concept. Again, stay general at first, explaining why the key concept is important. As you progress, let your presentation get more and more specific. In key concept number four, for example, you might begin by describing why compensation is required. Explain it's benefits. Again, stay general at this point. Only discuss things that apply to all compensation types. Once students understand why compensation is required, go into each specific compensation type in greater detail.


Reviewing class material

Another great benefit of the key concepts approach is that it facilitates review. You don't have to get every detail across on the first try. Just be sure they truly understand the general presentations. If students are getting confused with the details, back off a little. You'll be reviewing the material at some future time, and you can dig in deeper once students have had some time to absorb the material.


Again, it will probably be impossible to relate every detail of every key concept the very first time through. When describing the feature constant surface speed for turning centers, at first I'm only concerned with making sure students know what it does and how it works, and maybe the related CNC words. During a review (after discussing these ideas again), I'll dig deeper, explaining why constant surface speed can be a cycle time waster if it is not properly programmed. As long as students understand, I'll show a more efficient way of programming it.


You've got to be flexible. In the constant surface speed example, some students truly are bright enough to catch on to every detail the very first time. If most of the students in the class understand, by all means, go until they begin to become confused. Then back off and save the details for a future review.


When does the class end?

Another benefit of the key concepts approach is that it allows you to be flexible with how much material you get through. In many classes I've attended, there comes a point when the instructor realizes that they're not going to get through all of the material. They begin to speed up their presentations in hopes of completing the course.


By comparison, the key concepts approach allows more flexibility with regard to when the class ends. Since you're constantly working from general to specific, and since you decide how detailed to get in each presentation based upon student aptitude, you'll be able to let the class end at any time after you've covered the key concepts.


Admittedly, some classes will have students with more aptitude than others, meaning you'll be able to cover more (detailed) material. But as long as students understand the general presentations related to the key concepts, and as long as they have good support materials (manual), they will have proficiency with the material in the class. And with a good manual that reinforces class presentations, they'll be able to review on their own should the need arise.


Conclusion to part one

As we've demonstrated, the key concepts approach will help you to organize any curriculum. While we've been pretty specific, discussing how the key concepts can be applied to teaching CNC, you should be able to see how this approach can be applied to teaching just about anything.

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