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Shown vs. Created Dimensions

ptc-1868133
1-Newbie

Shown vs. Created Dimensions

What is the general feeling about using shown dimensions? I was told to always use them where possible from my first CAD administrator, but my current admin doesn't like them. Just let me know if you like shown dimensions or not and include your reasoning.
83 REPLIES 83
mlocascio
4-Participant
(To:ptc-1868133)

Not good! Be hesitant..be very hesitant!


mlocascio
4-Participant
(To:ptc-1868133)

Steve,



Yes, I have detailed SEVERAL sheet metal parts using shown dimensions. It's
as easy as you want it to be. Sheet metal is sort of a forte for me.



Mike


wfalco
14-Alexandrite
(To:ptc-1868133)

Mike,

FOUL!

WayneF

Mike, how do you create shown dimensions on the flat pattern if you
created your model in the formed state?

Brian S. Lynn
Technical Coordinator, Product Engineering

Michael,

Please, do not confuse preferences with knowledge or intelligence.
There are legitimate reasons that folks will choose one method over
another. There is not 'one right way' to drive Pro|E.

I believe that I made a coherent argument for the use of created
dimensions. I could, but will not, conclude that others who reach
different conclusions have a "low bar" mentality or that they do not
know how to use Pro|E. We each must use the methods that best suit our
own understanding of the software as well as the environment in which we
work (user base, available functionality, client acceptance, corporate
culture, etc.).

Actually, I would love to hear from folks who adhere to the 'always
shown dims' mantra what they find that it gains them. Most of the
arguments thus far have been along the lines of "it's the way it ought
to be" or "that's the way I was taught".

Shown dims only advocates, what does this method gain you that created
dims would not?

Doug Schaefer
--
Doug Schaefer | Experienced Mechanical Design Engineer
LinkedIn

I was retrained on ProE while working at Raytheon. At the time, they were adamant about using shown dimensions only. I was told that the reason was so that lower level drafting personnel could incorporate simple eco's by altering the drawing directly without needing to understand the model behind the drawing.
 
Where I work now, they are trying to transition to a Minimum Dimensioned Drawing process where the model is to contain all the infomation needed to produce the part, including all tolerancing. It makes sense under these conditions to create the model using the dimensions that you want to appear on the drawing. This would allow the machinist/inspector to not only use NC data for nominal dimensions, but also query the model to see what tolerance deviation is allowed.
 
Effectively, if you did make a drawing using a model created under this premise, you could have all shown dimensions.
 
Without making a judgment on either of these reasons, I have learned to redefine features very efficiently.
 
For the most part, I use shown dimensions. Occasionally I use created dimensions, usually for Interface/Installation type drawings to communicate overall dimensions of an assembly. These dimensions do not exist as model dimensions so cannot be shown.



 
Shown dims only advocates, what does this method gain you that created dims would not?
Doug Schaefer

I can tell you why we do it, though we do NOT use shown dim.s 100% of the
time, because we work with sheet metal and you cannot have shown
dimensions for the formed and the flat pattern both.

1. When the design is checked on the hand drawing the dimensions match
exactly what is in the part there is nothing beyond what we are interested
in specifying. So the dimension that says 3.44 is 3.44 and not 3.4368734.

2. Those who want changes to the part, mark up a print of the drawing, so
the "easy" change they see will be the same for the designer.

3. If the intent is communicated from the drawing the same as in the part,
a "new" designer will better understand the intent of the part and be able
to work on the part more easily.

4. This is just a preference... I like being able to modify a dimension in
the drawing and updating the design. I understand this doesn't work for
everyone or in every situation.

This is all garbage though if you are using top down design, though since
we here want to be able to reuse parts using top down design has to be
broken before saving into our vault as a rule.

Hope that clarifies,

Brian S. Lynn
Technical Coordinator, Product Engineering

Here are a couple of other responses to the 'why shown' thread that came
to me instead of the list. Helpful stuff, thanks folks.

Doug Schaefer

--
Doug Schaefer | Experienced Mechanical Design Engineer
LinkedIn

This thread is still going??



Shown -vs- Created

I use them both; they are good tools in the tool box so use them!

Just make sure you don't create dims on draft features, big time No No.



**Off Topic

And yes Batman is human and Superman is an alien and he can't imaginer
were as Batman is a successful business man with high intelligence.
Brains over Braun winner every time.

Then again both Batman and Superman protect life so for them to fight to
the death is absurd. But assuming this is a freak show of epic
proportion Batman wins. He gets Kryptonite boxing gloves and beats the
hell out of him.



Did you know Batman has a workstation in the bat cave with Proe and
Proman, how else does he come up with some kool shizznit

I wonder if he runs the 64bit version?

(lmao)







Jeff Lippeth
Engineering Group
NyproMold Chicago
P. 847-855-2226
F. 847-855-2303
- <">mailto:->
www.NyproMold.com

I agree that there are times where you need to be flexible, but I always teach my users to use Shown dimensions as the standard and then use created dimensions if needed.

Shown dimensions will allow quick modifications at the drawing level that translate back to the model. This is why PTC created a Parametric Modeling System. Using created dimensions as your default practice goes against that principle. Remember that I said at the beginning that there are times where a created dimensions is needed for proper communication to manufacture the part.


Another reason I love shown dimensions is because it teaches the Engineer to think about how they constrain their designs. You want to constrain your features the way you would communicate the information in the drawing. This again will allow for quick modifications by anyone down the road.

Remember that at the beginning I stated that using a created dimension when needed is perfectly fine. I would never agree that using created dimensions as a standard practice is a good thing. Using created dimensions when needed addresses most of the reasons people claim they need them but using Shown dimensions as your standard practice will yield far greater benefits.

When PTC shows a new customer what makes Pro/E a great tool, I guarantee you they pull up a drawing to make modifications on it quickly and show you how this translates back to your design. You don't need to sit there and delete created dimensions or reference them every time a change occurs.

PTC did give you the ability to create dimensions because they are times where the design intent does not capture a particular dimensions needed by your manufacturing process and you can always use them to fill in the holes. I would venture to say that PTC would consider Shown dimensionns the standard practice with created being a good secondary option.

That is my $.10 🙂

P.S. Superman always wins. He is the only true Superhero. All others wear costumes to change to their hero state. Superman's costume is a civilian because he was born a Superhero not the other way around.


"If you are not living life on the Edge, You are taking up too much space"



"Another reason I love shown dimensions is because it teaches the Engineer to think about how they constrain their designs. You want to constrain your features the way you would communicate the information in the drawing. This again will allow for quick modifications by anyone down the road."I strongly disagree with the above... I want my designers to constrain our features to function in the assembly, not to be tied down trying to think ahead to how it will be detailed. I use many assembly level features and references so that I'm sure my components work together. As a simple example, all my assembly screw holes are created coaxially to it's parent component in the assembly, or an axis in the assembly or skeleton part, therefore there aren't any location dimensions to show on the drawings. I tend to do this with many features. The last thing I want, is to give someone the ability to change something on a drawing, risking the chance that they will not think about the consequences of other related parts.

While it is true that we could use relations so that there would be show-able dimensions, that would also negate the ability to change it via the drawing anyway.

"PTC did give you the ability to create dimensions because they are times where the design intent does not capture a particular dimensions needed by your manufacturing process and you can always use them to fill in the holes. I would venture to say that PTC would consider Shown dimensionns the standard practice with created being a good secondary option."I have always thought that this topic confuses 'design intent' with 'drawing intent'. The design intent always takes priority in my opinion. My design intent is part/assembly functioning, not what the drawing will look like. We can always figure out a way to detail it, especially when manufacturing or inspection processes may not be known at the time the part is modeled.

My guess is PTC won't even get involved in this topic. I know I wouldn't if I were them. They have a product that is flexible enough to work for many different customers processes and techniques. If a customer wants to have complete control of the model via the drawings, Pro/E can do that... If another doesn't care as much about the drawings and wants to have the ability to try advanced modeling techniques, they may, without worrying that they then can't create a drawing of their parts.

So we have the best of both worlds. I see no need to force anyone into one technique or another. If it happens that a feature has show-able dimensions, I'll show them. If not I don't sweat it, just create the dimension I want and move on.

But I do not like the use of created dimensions as an excuse or a work-around for poor modeling techniques. I'm sure this problem has driven some opinions. There are other ways to deal with proper modeling techniques (other than slapping a mouse across someones head, that doesn't always help)

Have a good weekend!
Dave

That's the bottom line

It's flexible and if you really look deep enough you will realize that the
argument works depending on your situation and internal process.

We don't work with allot of assemblies for example. Most of our design
effort is at the part level. So I can see how this would be different for
you.

The best thing to do is to figure out what works best for your companies
situation and standardize on it.

I do enjoy an environment where the drawing and part are one in the same
as far as information and control. That is not the case for everyone. I
do know PTC has sold people on this idea, not to say that using the tool
to conform to your application is wrong.

Damián Castillo
CAD & Administration Manager
Engineering Department
Hensley Industries, Inc.



David Reiser <->
08/01/2008 10:53 AM

To
Damian Castillo <->
cc
-
Subject
Re: [proecad] - RE: Shown vs. Created Dimensions







"Another reason I love shown dimensions is because it teaches the Engineer
to think about how they constrain their designs. You want to constrain
your features the way you would communicate the information in the
drawing. This again will allow for quick modifications by anyone down the
road."
I strongly disagree with the above... I want my designers to constrain
our features to function in the assembly, not to be tied down trying to
think ahead to how it will be detailed. I use many assembly level
features and references so that I'm sure my components work together. As
a simple example, all my assembly screw holes are created coaxially to
it's parent component in the assembly, or an axis in the assembly or
skeleton part, therefore there aren't any location dimensions to show on
the drawings. I tend to do this with many features. The last thing I
want, is to give someone the ability to change something on a drawing,
risking the chance that they will not think about the consequences of
other related parts.

While it is true that we could use relations so that there would be
show-able dimensions, that would also negate the ability to change it via
the drawing anyway.
"PTC did give you the ability to create dimensions because they are times
where the design intent does not capture a particular dimensions needed by
your manufacturing process and you can always use them to fill in the
holes. I would venture to say that PTC would consider Shown dimensionns
the standard practice with created being a good secondary option."
I have always thought that this topic confuses 'design intent' with
'drawing intent'. The design intent always takes priority in my opinion.
My design intent is part/assembly functioning, not what the drawing will
look like. We can always figure out a way to detail it, especially when
manufacturing or inspection processes may not be known at the time the
part is modeled.

My guess is PTC won't even get involved in this topic. I know I wouldn't
if I were them. They have a product that is flexible enough to work for
many different customers processes and techniques. If a customer wants to
have complete control of the model via the drawings, Pro/E can do that...
If another doesn't care as much about the drawings and wants to have the
ability to try advanced modeling techniques, they may, without worrying
that they then can't create a drawing of their parts.

So we have the best of both worlds. I see no need to force anyone into
one technique or another. If it happens that a feature has show-able
dimensions, I'll show them. If not I don't sweat it, just create the
dimension I want and move on.

But I do not like the use of created dimensions as an excuse or a
work-around for poor modeling techniques. I'm sure this problem has
driven some opinions. There are other ways to deal with proper modeling
techniques (other than slapping a mouse across someones head, that doesn't
always help)

Have a good weekend!
Dave


Today I had to write up a long explanation as to why a drawing needed corrected. The production drawing had staggered pairs of contacts dimensioned from the right, the customer drawing had them and the mating board dimensioned from the left. When the customer ordered a part with an even number of staggered pairs, guess what? It did not match the customer drawings board layout. Lucky for the customer, they used the part to make their board.

How could this happen? Created dimensions.

Another drawing has a feature dimensioned four times in four different views, and not one is a reference dimension.

How could this happen? Created dimensions.

It takes a minute or two to redefine a part or assembly so that it matches your new design intent. You show all your dimensions and you don't get duplicates. Parametrics is great if you are willing to put forth a little extra effort to do things right. In the long run, problems are greatly minimized. You have robust models AND drawings. Yes, "AND drawings", since that is what a majority of businesses still use as the final say-so as to what is being manufactured. Doesn't that actually make the drawing just as important as the model? So isn't the drawing reflecting the model important? You do not get that with created dimensions, at least I have not noticed it over the 15 years of using Pro/E and mentoring other users.

The above is just two problems caused by created dimensions (and I have seen many), one that could have cost thousands of dollars to a customer in incorrect parts being made, lost time, and potentially lost business, and thousands of dollars to our company in either lost business or paying to correct the mistake. The other speaks of the sloppyness in drawings that do not even meet standards. Could there have been extra time and effort used in checking the drawings to make sure they were correct? Sure. Is this what we want to do every time there is a new drawing created? I wouldn't think so.

Isn't this why we purchased Pro/E in the first place...to be able to get to the market faster with fewer mistakes?

Yes, created dimensions are needed ON RARE OCCASIONS, that is why they are available in Pro/E. Otherwise I would feel better knowing that any Pro/E drawing or model I need to work on down the road is parametric with each other, saving me both time and money to make changes.

Joe Ordo

To: -Subject: [proecad] - RE: Shown vs. Created DimensionsFrom: -Date: Fri, 1 Aug 2008 06:30:34 -0700
I agree that there are times where you need to be flexible, but I always teach my users to use Shown dimensions as the standard and then use created dimensions if needed.
Shown dimensions will allow quick modifications at the drawing level that translate back to the model. This is why PTC created a Parametric Modeling System. Using created dimensions as your default practice goes against that principle. Remember that I said at the beginning that there are times where a created dimensions is needed for proper communication to manufacture the part.
Another reason I love shown dimensions is because it teaches the Engineer to think about how they constrain their designs. You want to constrain your features the way you would communicate the information in the drawing. This again will allow for quick modifications by anyone down the road.
Remember that at the beginning I stated that using a created dimension when needed is perfectly fine. I would never agree that using created dimensions as a standard practice is a good thing. Using created dimensions when needed addresses most of the reasons people claim they need them but using Shown dimensions as your standard practice will yield far greater benefits.
When PTC shows a new customer what makes Pro/E a great tool, I guarantee you they pull up a drawing to make modifications on it quickly and show you how this translates back to your design. You don't need to sit there and delete created dimensions or reference them every time a change occurs.
PTC did give you the ability to create dimensions because they are times where the design intent does not capture a particular dimensions needed by your manufacturing process and you can always use them to fill in the holes. I would venture to say that PTC would consider Shown dimensionns the standard practice with created being a good secondary option.
That is my $.10 🙂
P.S. Superman always wins. He is the only true Superhero. All others wear costumes to change to their hero state. Superman's costume is a civilian because he was born a Superhero not the other way around.
"If you are not living life on the Edge, You are taking up too much space"

I think we've beaten this poor deceased equine down enough for another year
or two reprieve. Up for some more? For even more workplace distraction, we
can start similar enlightening and engaging discussions in such highly
controversial areas as:

Wabbit season vs. duck season (a classic)
Pepsi vs. Coke (eternal)
Democrats vs. Republicans (oy vey!)
Boxers vs. briefs (keep it discreet!)
Alien vs. Predator (sure whatever...)
1969 NY Mets vs. the 1990 SF 49ers (is this another stupid ESPN dream team
concoction?)
Playstation3 vs. Xbox360 (for "children" only)
Men vs. Women (be careful with this one!)
Blu-ray vs. HD DVD (moot now, but a favorite!)
Mac vs. Windows (even older than shown dimensions vs. created dimensions)

The limit is only your imagination...

Hey, it's Friday. 😉

_____

You've left out the 2nd best topic . . . . engineers vs. designers


Gingeror Mary Ann?

In Reply to:
Wabbit season vs. duck season (a classic)
Pepsi vs. Coke (eternal)
Democrats vs. Republicans (oy vey!)
Boxers vs. briefs (keep it discreet!)
Alien vs. Predator (sure whatever...)
1969 NY Mets vs. the 1990 SF 49ers (is this another stupid ESPN dream team
concoction?)
Playstation3 vs. Xbox360 (for "children" only)
Men vs. Women (be careful with this one!)
Blu-ray vs. HD DVD (moot now, but a favorite!)
Mac vs. Windows (even older than shown dimensions vs. created dimensions)

Mary Ann



Ginger was a bimbo...



_____

Ginger, there is something about a long legged red head


Nope, May Ann. Without a doubt.


I'm thinking this horse is about as beaten as it's going to get. I will
say that proper checking would have solved both issues below and that
there is nothing to stop one, at least in the first instance, from
creating the same scenario using shown dims.

Also, many have implied that created dims are not 'parametric'. They
most certainly are, they just follow rather than lead.

As far as what PTC would recommend, well, now they are pushing model
based definition hard. I the 3D drawing class I took in Tampa in 2007,
the instructor added all created dims in the annotation elements that he
created within the part model itself. He then showed the annotation
elements in the drawing. So, shown created dims.

That ought to give the hard core shown dim fans fits. 😄


Doug Schaefer
--
Doug Schaefer | Experienced Mechanical Design Engineer
LinkedIn

My Ex was a Ginger who turned into a monster, my girlfriend is more the Mary-Ann type.
At some point you're going to want to talk.


BOTH !!!

Hey David,

I agree with you that this topic always seems to loose focus and morph
into a "design intent" vs "drawing intent" topic. I think it is because
of a general miss-understanding of drawing requirements or possibly just
having unusual drawing requirements. It is my interpretation of the
ASME standards that my organization adheres too; that design intent and
drawing intent is one and the same (See following excerpts.) The actual
process of applying a dimension (show vs create) on a drawing or
annotation plane has nothing to do with it. Design intent can be
captured by either process (show or create) and can be left out by
either process as well. I take it from you statements below that your
organization is one that makes a distinction between design intent and
drawing intent. Could you elaborate on how your organization defines
drawing intent differently from design intent?



ASME Y14.8M

This Standard does not intend to suggest that the types of casting and
forgings presented herein are more important than those not presented,
nor does it presume to restrict drawing content to only that which
appears herein. Drawings must convey design intent and be complete
enough that a designed part can be produced from them.



ASME Y14.5M

1.4 FUNDAMENTAL RULES

Dimensioning and tolerancing shall clearly define engineering intent and
shall conform to the following.



ASME Y14.5M (appendix)

The purpose of this Appendix is to assist the user in selecting the
correct geometric characteristic for a particular application. Decision
diagrams have been developed that are based on design requirements and
the application of datums, geometric controls, and modifiers. The
diagrams encourage the user to think in terms of design intent and
functional requirements, and assist in the development of the contents
of feature control frames.



When documenting design intent, the user must consider both the
stabilization of the part and the functional requirements of the
individual features. See Fig. E-1. In dealing with Individual Features,
both Form and Profile controls must be considered. If the application
deals with Related Features, then Location, Orientation, Runout, and
Profile controls must be considered.



ASME Y14.13M

This Standard does not presume to restrict drawing content to only that
which appears herein. Drawings must convey design intent and be complete
enough that a designated part can be produced from them.



ASME Y14.5.1M

The subject of datums also led to many hours of work by the
Subcommittee. The current definitions, presented in Section 4, were the
result of evaluating a number of approaches against four criteria: 1)
conformance to Y14.5M; 2) whether a unique datum is defined; 3) whether
the definition is mathematically unambiguous; and 4) whether the
definition conveys design intent. A fifth criterion, whether the
definition was measurable, was not used for reasons discussed above. The
end result of this work was based on feedback from the Y14.5M
Subcommittee when Y14.5.1 presented its analysis, and involved a change
in its thinking about datums. The initial view of a datum was as
something established before a part feature is evaluated. The current
definitions involve a different view that a datum exists for the sake of
the features related to it. The result was a consolidation of the issues
involved with "wobbling" datums and the issues involved with datum
features of size at MMC or LMC. These apparently dissimilar issues are
unified mathematically in the concepts of "candidate datum" and
"candidate datum reference frame."



DRM based on MIL-T-10000

5.5 FUNDAMENTAL RULES OF DIMENSIONING. The following rules shall

I usually try to stay out of this conversation but I have to agree with
Jim here. I never understood where design intent and drawing intent
differed. When a drawing and model out for manufacture I see the
drawing as what they use to validate the parts before sending them to
the customer. Or that the drawing intent is to display the design
intent making them one and the same. How does the opposing opinion view
them as different?

One of my pet peeves is marking up a drawing to get the dimensions I
need to revise an old part and finding that those dimensions do not
exist. Then I have to find what combinations of dimensions I need to
change to get the drawing dimension correct without changing
inadvertently changing something that shouldn't.

Pro/E vs. SolidWorks?
<ducking>

Just because I have to...

Boxers vs. briefs (keep it discreet!) > neither..... Kilt 🙂

In Reply to:

I think we've beaten this poor deceased equine down enough for another year
or two reprieve. Up for some more? For even more workplace distraction, we
can start similar enlightening and engaging discussions in such highly
controversial areas as:

Wabbit season vs. duck season (a classic)
Pepsi vs. Coke (eternal)
Democrats vs. Republicans (oy vey!)
Boxers vs. briefs (keep it discreet!)
Alien vs. Predator (sure whatever...)
1969 NY Mets vs. the 1990 SF 49ers (is this another stupid ESPN dream team
concoction?)
Playstation3 vs. Xbox360 (for "children" only)
Men vs. Women (be careful with this one!)
Blu-ray vs. HD DVD (moot now, but a favorite!)
Mac vs. Windows (even older than shown dimensions vs. created dimensions)

The limit is only your imagination...

Hey, it's Friday. 😉

_____

Design intent is that there be a .025" gap between parts A & B. With a
curve in a skeleton to describe the parting line between them, I design
part A line to line with the curve, part B .025" from the curve. Design
intent captured simply, cleanly and directly.

My drawing intent is to communicate how to make or perhaps inspect the
individual parts. That .025" dim is meaningless to the machinist or
molder or QA technician who has to make or inspect Part B, they need a
dimension from some other geometry. Part A has no dimension to the
mating surface, so I need to provide one.

Doug Schaefer
--
Doug Schaefer | Experienced Mechanical Design Engineer
LinkedIn

I agree.

I know there are some people out there with situations they will justify
why they create dimensions. Good thing is, Pro/E will let you do it. I
am just glad I don't have too. 🙂

Damián Castillo
CAD & Administration Manager
Engineering Department
Hensley Industries, Inc.



Joseph Ordo <->
08/01/2008 11:48 AM

To
Damian Castillo <->, <->
cc

Subject


what your other wise saying is that you enjoy being comando?

To: -Subject: [proecad] - RE: Shown vs. Created DimensionsFrom: -Date: Fri, 1 Aug 2008 11:53:39 -0700
Just because I have to...
Boxers vs. briefs (keep it discreet!) > neither..... Kilt Smiley HappyIn Reply to:
I think we've beaten this poor deceased equine down enough for another yearor two reprieve. Up for some more? For even more workplace distraction, wecan start similar enlightening and engaging discussions in such highlycontroversial areas as:Wabbit season vs. duck season (a classic)Pepsi vs. Coke (eternal)Democrats vs. Republicans (oy vey!)Boxers vs. briefs (keep it discreet!)Alien vs. Predator (sure whatever...)1969 NY Mets vs. the 1990 SF 49ers (is this another stupid ESPN dream teamconcoction?)Playstation3 vs. Xbox360 (for "children" only)Men vs. Women (be careful with this one!)Blu-ray vs. HD DVD (moot now, but a favorite!)Mac vs. Windows (even older than shown dimensions vs. created dimensions)The limit is only your imagination...Hey, it's Friday. ;-)_____ From: Damian Castillo [
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