||Copyright 2012, CNC Concepts, Inc.
November 15, 2012
Welcome to Issue 92 of The Optional Stop. I hope you
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!
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
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
Each of these classes can be followed up with a
programming class that teaches G code level, manual
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
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).
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
To evaluate student understanding, there are three more
activities, tests, coordinate sheet exercises, and
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
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
Basic CNC classes
If students do not have previous
If students have previous shop
Advanced CNC classes
Top of page
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
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
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
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
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
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
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
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
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
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
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
- Machining center
- Turning center setup and
- Turning center programming
Do you want to know more?
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.
Top of page
Using our on-line CNC content as part of your in-plant
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:
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.
Top of page
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
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).
Top of page
Unlimited fixture offsets (Fanuc)
Submitted by G. Kilpatric of
Use this method to create extra work
offsets if your machine is limited to just six (G54 TO
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!
O0002(WORK OFFSET SUB-SET UP
FIXTURE OFFSETS HERE!)
G0TO#1 (Seq No / Line search)
(AND SO ON..............)
Top of page
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
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
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.
Top of page
The Optional Stop newsletter
is published quarterly by CNC Concepts, Inc. and is distributed
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