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November 15, 2012

Dear Subscribers,

Welcome to Issue 92 of The Optional Stop.  I hope you enjoy it. 

Sorry for being so late with this issue. I’ve been working on moving my on-line class content to a new platform and wanted to finish that task so I could include information about it in this issue. Please see the Product Corner for how individuals can benefit. See the Instructor Notes to see how we can help CNC-teaching schools. And see Manager’s Insight to see how we can help CNC-using companies that have in-plant training classes.

It’s great to hear that – and finally experience – manufacturing is finally making a comeback in the U.S. CNC teaching schools are working overtime to bridge the gap between the skills companies need and peoples’ current skill levels. Let’s keep the ball rolling!

 

Mike Lynch

IN THIS ISSUE
Product Corner: Our on-line CNC classes
Instructor Note: Using our on-line content to supplement your CNC classes
Manager's Insight: Using our on-line CNC content as part of your in-plant training program
G Code Primer: Which is better, G53 or G28?
Macro Maven: Unlimited fixture offsets (Fanuc)
Parameter Preference: A parameter related to circular motion
Safety First: Training and task simplification – both enhance safety

Product Corner: Our new on-line CNC classes

We’ve moved the content for our on-line classes to iSpringOnline.com. It’s a great platform – simple to use, it has a great media player, and there’s lots of room for content. Almost all of the presentations for our basic classes, as well as for our Parametric Programming class are now narrated, so students can hear as well as see the videos. Note that we still maintain a silent version of most classes for the hearing impaired and for people who have computers without audio. And we’ve added two new basic courses, providing a second approach to people who want to learn about CNC.

The new platform has also allowed us to expand the user base:
Individuals who want to learn CNC on their own will still find an inexpensive and easy-to-use, yet comprehensive set of on-line classes.

But now, instructors teaching for CNC-teaching schools will find an excellent way to supplement their face-to-face classes. We now provide instructor access to allow monitoring of student progress (seeing what students are working on, checking test scores, etc.).

And companies with in-plant training programs can now use our content to provide learning materials that employees need to become proficient with CNC.

We address the two most popular types of CNC metal cutting machine tools: machining centers (mills) and turning centers (lathes). As stated, we offer two approaches to help students learn the basics of CNC. Current basic machining practice experience determines which approach will be used.

Students that have no prior shop experience (as is often the case when companies hire new people) should begin with a setup and operation class (again, we have one for machining centers and another for turning centers). This class begins with two lengthy lessons that prepare them to learn about CNC. Topics include shop safety, shop math, blueprint reading, tolerance interpretation, measuring devices, machining operations, and cutting tools. We then provide ten more lessons to show how to get a machine up and running – and to complete a production run.

Each of these classes can be followed up with a programming class that teaches G code level, manual programming.

Students with prior shop experience (as is often the case with students attending CNC-teaching schools) can dive right into CNC, taking one of the programming, setup, and operation classes. Again, there’s one for mills and one for lathes. With this approach, we begin with programming, but any time we come across a programming topic that has implications of how setups are made and/or production runs are completed (like program zero, tool length compensation, and cutter radius compensation), we address it. By the time we get to the setup and operation portion of the class, many of the related topics will be quite familiar.

We also have advanced CNC classes to address advanced CNC techniques, parametric programming, and improving the utilization of your CNC machine tools. See the full list of classes below.

On-line classes include several activities:

To present material, we use presentations and reading material.

  • Presentations utilize an easy-to-use media player, and again, most are narrated. They provide a very visual way to learn, and can be viewed on any device with support for Flash content (many portable devices now provide this kind of support).

  • Reading material is provided in the form of .pdf (Adobe Acrobat) files. These files can be viewed on the computer screen or they can be printed. They can also be saved for future reference. (Presentations cannot be saved).

To evaluate student understanding, there are three more activities, tests, coordinate sheet exercises, and programming activities.

  • All lessons contain tests. Once students have studied the presentations and reading material, they take the test. Results are immediate so students will know how they did right away. Results are also emailed to me (or the instructor, if taking the class through a CNC-teaching school) so grades can be recorded. Complete results are then emailed back to the student.

  • Many lessons in programming-related classes also include coordinate sheet exercises and programming activities. Like reading material, these are .pdf files which students print and fill in. They then type them and email them to me (or again, the instructor) for grading. After grading is done and grades are recorded, results are emailed to the student.

Links to our web site that provides more information.

Basic CNC classes

If students do not have previous shop experience:

If students have previous shop experience:

Advanced CNC classes

 

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Instructor Note: Using our on-line content to supplement your CNC classes

Our on-line CNC content itself is pretty well described in the Product Corner and web page links. The only additional point here is that since most CNC-teaching schools require students to take certain basic machining practice classes as prerequisites to CNC classes, the two most popular sets of on-line content will be for Machining Center Programming, Setup, and Operation and Turning Center Programming, Setup and Operation. If you happen to teach classes for local industry on an in-plant basis, you may additionally have need for the content related to setup and operation.

We’d like to better explain how our CNC content can help instructors who are teaching CNC classes. This includes instructors teaching in a CNC-teaching school as well as instructors teaching in a CNC-using company.

First, a little history. We’ve been providing curriculums to help instructors teach CNC classes for many years. Last year, over eighty schools used our materials. Student materials for our curriculums include a manual and, for some classes, a workbook. Instructor materials include PowerPoint presentations and lesson plans. And again, these materials have been very well-received by CNC-teaching instructors.

In early 2011, we began getting requests for on-line content that would replace materials that students currently purchase for the CNC classes they take. The thought was that if students have notebook computers, they shouldn’t have to lug around physical books. Instead, they should be able to download the related material from a web site. So one of the objectives for our on-line content does just that. Students no longer have to purchase student manuals. Instead, they download reading material for each lesson.

Reading material can be viewed on the computer screen or printed. It can also be saved. And if all you want is to eliminate the need for physical manuals, we can tailor the on-line content for your school to just include the reading materials for your class/es.

But early on, we realized that we could do much more than just provide students with reading materials. Since several of our curriculums utilize workbooks that students fill in and turn in as they go through the class, we targeted them for elimination too. Exercises have been converted to on-line tests that are automatically and immediately graded. Results can be emailed to you, or any instructor in your school, so that grades can be recorded. (We even provide an Excel file grade book for recording and summarizing grades.)

Our curriculum workbooks also include coordinate sheet exercises and programming activities. So we put them on line too. Like reading material, they are in the form of .pdf (Adobe Acrobat) files that can be printed. Once students complete one, they can email it to you (a special class activity makes it easy to correspond with the instructor) or they can hand it in face-to-face. We provide answers so you can easily grade them. Answers are provided in the form of a response email that you can send to students once you finish grading and recording the grade. And there’s room in the Excel grade book to record assignment grades.

So again, if all you want is to provide on-line reading materials and/or tests and/or coordinate sheet exercises and/or programming activities, we can tailor your on-line content accordingly.

But we also decided to include visual presentations in our on-line CNC content. Every lesson has one and most are narrated. If you are currently using any of our CNC curriculums, they parallel the PowerPoint presentations you use when delivering your lectures. But the on-line presentations are aimed at students, being self explanatory and extremely tutorial. They are displayed in a great media player and can be shown from any devices that support Flash content (many portable devices support Flash content).

While our intention is to supplement your face-to-face instruction, these presentations stand on their own pretty well. If a student misses a lecture, they can easily catch up without you having to go through the material again. In similar fashion, if a student wants to review a lesson, they won’t need you to do it. And, of course, you can assign the viewing of presentations as homework.

For instructors who are currently using our CNC curriculums, rest assured that this on-line content perfectly parallels our curriculums. That is, we provide the same Key Concepts and lessons – and in exactly the same order as we do in the curriculums. While tests are in a different form, they parallel the exercises in the workbook. And on-line coordinate sheet exercises and programming activities are exactly the same as they are in the workbook. This should make it very easy to incorporate our on-line content into your current CNC classes.

What you’ll get

Instructors using our on-line content will receive two accounts: an instructor account and a student account. The instructor account will give you access to student progress. You’ll be able to quickly track what your students have worked on – as well as see the results of the tests they’ve taken. You’ll also be able to add and remove students from your classes.

Since it’s not easy to see what students see from the instructor account, we also provide you with a student account. This will be most helpful as you get started to get familiar with the material, and will let you demonstrate the system to your students or help them if they have questions.

And again, we provide instructors with a grade book for each class and a set of answers that will be used for grading.

Getting started /setting up

The system is pretty flexible, so there are a few choices to make before we can set up the system to include your school. You can, for example, specify the number of times you want students to be able to take tests. And you can specify whether you want test results to be emailed to you or whether you’d rather log in to the system to see student progress. And of course, you must choose which content items you wish to include (presentations, reading material, tests, coordinate sheet exercises, and programming activities).

Pricing

Pricing is different (much lower) than for the on-line classes we provide to individuals. This is because you’ll be doing the evaluation (grading) and corresponding with students when they have questions. The prices listed below assume you are using all the content for a given class (again, presentations, reading material, tests, etc.)

  • Machining center programming, setup, and operation ($99.00)
  • Turning center programming, setup, and operation ($99.00)
  • Machining center setup and operation ($69.00)
  • Machining center programming ($69.00)
  • Turning center setup and operation ($69.00)
  • Turning center programming ($69.00)

Do you want to know more?

Admittedly, there’s a lot of information here to digest, especially if you haven’t been using our curriculum materials. If you’d like to discuss our on-line content further, give us a call at (847) 639-8847. We’d be happy to allow you both instructor level and student level access for a ten-day trial period so you can check out the system.

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Manager's Insight: Using our on-line CNC content as part of your in-plant training program

The Product Corner in this issue shows how our on-line CNC content can be used by individuals wanting to learn about CNC. Instructor Notes describes how our on-line CNC content can help in CNC-teaching schools. Here, we’d like to address how companies that have in-plant training programs can use our on-line CNC content.

If you have but a few people to train (under ten), please use our on-line classes (shown in the Product Corner). We’ll do the grading and answer any questions as students go through the material.

But if your company has many people to train, and especially if you are selecting a special person in your company to act as the instructor/facilitator, you should consider how our on-line CNC content can help. Please read the Instructor Notes and Instructor Notes articles. The points made about on-line content for individuals and schools applies to companies as well. The only difference is that companies need a minimum of ten students to qualify for the discounted pricing we show.

Most CNC-using companies today are struggling to find, hire, and train people to attend to their CNC machine tools. Entry level people commonly begin with the position of CNC operator. We have two sets of content the can really help you bring people up to speed quickly:

  • Machining Center Setup and Operation

  • Turning Center Setup and Operation

Each class includes four Key Concepts, which are further divided into lessons. The content for each lesson in the setup and operation classes includes a narrated presentation, reading material and a test. Test results can be automatically emailed to your instructor/facilitator.

You can follow up with classes for programming (again, one for turning centers and another for turning centers).

Please contact us to further discuss how our on-line CNC content can help with your in-plant CNC training classes (847) 639-8847.

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G Code Primer: Which is better, G53 or G28?

Suggested by Jason Michaud of Chippewa Valley Community College

Mike: We are having a discussion in our department if we should have students send the axis home with a G28 or a G53. For some reason I like using the G28 but others prefer G53. Is there an advantage of one over the other and which one promotes better programming practice?

  • G28 G91 Z0 or G53 Z0

One advantage to using G28 is that the axis origin lights will come on which was very important in the days of using G92 to assign program zero - when the machine had to be in a planned position before the cycle was activated. This made it possible for an operator to check whether the machine was at the zero return position (the lights would be on). But with fixture offsets (or geometry offsets on lathes) this is no longer so important.

Another "advantage" is that G28 is universal. For companies that have very old machines (no fixture offsets - or possibly G52 is not allowed), they can use the same command for all machines.

Finally, even today, I think some machine tool builders don't make G53 part of there standard package, meaning the G28 method will always work (or G53 would have to be purchased as an option).

The biggest reason some people don't like G28 is the G91 that goes with it. If they forget it, the machine will first go to the program zero point (possibly crashing) then go home. Or if they subsequently forget the G90 in upcoming motion commands, the machine will still be in the incremental mode.

Generally speaking, if a company is sure that they can use G53 on all of their machines (maybe the company is just getting started in CNC), I'd recommend using G53. But if they have any concern about compatibility, I'd recommend using G28.

One last point about using G53. I'm not sure if it is influenced by the common fixture offset (fixture offset number zero). I don't think it is, but it would be worth testing. When a value is placed in the common fixture offset, the point of reference for fixture offset entries is moved from the zero return position to a more logical place - possibly a location point on a sub-plate.

To test, simply put a -3.00 value in the Z axis register of the common fixture offset (don't forget to clear it after the test!). Then give the command G53 Z0 in MDI mode. Does the machine still go to the zero return position, or is it three inches below? If G53 is affected by the common offset, I would NEVER recommend using it. Someday, the user may need to use the common offset, which would mean they'd have to change lots of programs.

If anyone performs this test, would you let me know the outcome? I’ll post your results in an up-coming issue of The Optional Stop (giving you credit, of course).


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Macro Maven: Unlimited fixture offsets (Fanuc)

Submitted by G. Kilpatric of Nichol McKay.

Use this method to create extra work offsets if your machine is limited to just six (G54 TO G59).

In your main program assign a value to a variable, the example below uses #1,you can have hundreds of individual alterable offsets.

Every coordinate system is G54, it uses the sub program to set the work offset required, when finished it jumps down to the end of the sub program and back into the main machining program.

Make up a table so you can keep track of which work offset is used for what setup/part.

Be careful what variable (#) you use as these maybe used elsewhere for other purposes.

I’ve used this method for over 12 years and it works great!

  • O0001(EXAMPLE PROGRAM)

  • G90G80G40G17G21M9

  • G91G30Z0M5

  • G90


  • T1(A TOOL)

  • M6

  • T2

  • M1
    #1=1 (Assign 1 to variable #1)

  • P0002M98

  • G0G90G54X-50Y100S1000M3

  • M8

  • G43Z100.H1

  • G98G81Z-10R2F500

  • G80

  • G0Z100M9

  • G91G30X0Y0Z0M5

  • G90


  • T2(A TOOL)

  • M6

  • T3

  • M1

  • #1=2 (assign 2 to variable #1)

  • P0002M98

  • G0G90G54X50Y-100S1500M3

  • M8

  • G43Z100.H2

  •  

  • G98G81Z-20R2F500

  • G80

  • G0Z100M9

  • G91G30X0Y0Z0M5

  • G90

  • M30

 

  • O0002(WORK OFFSET SUB-SET UP FIXTURE OFFSETS HERE!)

  • G0TO#1 (Seq No / Line search)

  • N1G10G90L2P1X-111.Y-107.Z-300.(1ST WCS)

  • GOTO99

  • N2G10G90L2P1X-150.Y-152.Z-300.(2ND WCS)

  • GOTO99

  • N3G10G90L2P1X-150.Y-150.Z-300.(3RD WCS)

  • GOTO99

  • N4G10G90L2P1X-33.Y-114.Z-300.(4TH WCS)

  • GOTO99

  • N5G10G90L2P1X-120.Y-50.Z-300.(5TH WCS)

  • GOTO99

  • N6G10G90L2P1X-155.Y-10.Z-300.(6TH WCS)

  • GOTO99

  • N7G10G90L2P1X-103.Y-127.Z-300.(7TH WCS)

  • GOTO99

  • N8G10G90L2P1X-110.Y-10.Z-300.(8TH WCS)

  • GOTO99

  • N9G10G90L2P1X-120.Y-150.Z-300.(9TH WCS)

  • GOTO99

  • (AND SO ON..............)

  • N99 M99

 

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Parameter Preference: A parameter related to circular motion

As you know, there are two ways to specify the size of a circular motion. The easiest way, especially for manual programmers, is to use the R word to specify arc size. While using the R word is easy, it has a limitation. Just about any value placed in the R word will work – that is, it will cause the machine to do something, and not generate any kind of alarm. The circular motion, however, will not be correct unless the R word is correctly specified.

The second way is to use I, J, and K – which are directional vectors with Fanuc and Fanuc-compatible controls. They specify the distance and direction in each axis from the start point of the arc to the center of the arc. I specifies the distance and direction in X. J specifies the distance and direction in Y. And K specifies it for Z.

Directional vectors are not nearly as forgiving as using the R word. Even a tiny error can generate an alarm. In a sense, using directional vectors can be considered better to use than the R word since an alarm will be generated if they are not specified nearly perfectly.

If you use directional vectors – or if the CAM system you use does – it is important to know that a parameter controls just how much an I, J, or K word can be off and still work. It is usually set to 0.0001 inch, meaning – again – even a tiny mistake can result in an alarm. This also means that if your CAM system is not perfect, it can cause circular motions that could generate alarms.

To find the parameter, look in the circular motion description of your Fanuc manual. You should find it in the notes after the description. The parameter is usually named something like INTOL – for in-tolerance. And of course, if you’re experiencing alarms when using directional vectors, you can increase it’s value.

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Safety First: Training and task simplification – both enhance safety

Normally we talk about training and task simplification with the emphasis on how it affects the skill level required to perform complex tasks. You can allow the task to remain complex and raise the skill level of the person performing the task or you can simplify the complex task so that even a lesser-skilled person can efficiently perform it.

We also relate this to productivity. We can raise the skill level to make it possible to more quickly perform tasks or we can simplify the task so that the task is easier (and faster) to perform.

But there is a third benefit having to do with training and task simplification. The safety related to any task is directly related these issues. The skill level of the person performing the tasks has a lot to do with how safe the task is to perform. You should easily agree that well trained people are less apt to make mistakes that can lead to dangerous situations. Indeed, people that are not well trained can be very dangerous. On the other hand, lowering the skill required to perform the task will also minimize the potential for dangerous mistakes.

To improve safety for a particularly dangerous task, we recommend incorporating both techniques. Target the task in your in-plant training sessions. While at the same time, consider ways to make the task easier to perform.


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