The Legend of Layer 21 5

[TheTick]

Wherever I go, Layer 21 is the de facto standard layer for sketches, and layer 61 is where the absolute CSYS resides. This was the case when I started UG in 1995. It's still the case today. I've seen it in many places and many industries.

How did this come to be? It may have started with McDonnel-Douglas, which seemed to drive the UG culture from the early days. Maybe it's a GM thing?

Design Visionaries, which does the lion's share of NX training on the West Coast seems to be a driving force in perpetuating the Layer 21 dogma, but they did not originate it.

What do we know about the "Legend of Layer 21"?

Honesty may be the best policy, but insanity is a better defense.

http://www.EsoxRepublic.com

-SolidWorks API VB programming help

 

[3DDave]

Where UG came from:

http://www.cadhistory.net/19 Siemens PLM Software.pdf

Unigraphics originated from United Computing. No idea about layer 21, but it might predate McAuto.

 

[JohnRBaker]

NO, it did NOT predate McAuto since until the R1 release of Unigraphics, which was in 1978, AFTER the acquisition of United Computing by McDonnell Douglas, UG had ONLY 14 Layers. It was the R1 release which increased the number of Layers to 256. I can say that as far as the Unigraphics development team was concerned, they had nothing to do with making any Layer a default other than Layer 1 and the 'hidden' layers (those numbered 257 and higher).

I suspect that this could have come from the so-called 'GM kit', which was developed by the GM people for both internal use and for use by their suppliers. While McDonnell Douglas also had internal standards, they were not as adamant about imposing them on others, certainly not like GM was famous for later on. Actually, I suspect that is the EDS people who were so set on imposing standards, as it would add to the perception that they were 'adding value', which was a significant part of their 'business model' when it came to how they did business with their customers, and even though EDS, at least for the first several years that UG was being implemented at GM, was owned by GM, they still considered GM as a 'customer' rather than as an owner, which produced it's own set of interesting situations ;-)

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[3DDave]

Sorry for striking such a sensitive nerve with an admittedly speculative comment.

 

[looslib]

We had layer 10 as our standard modeling layer for parts.

For design engineering, the following are the basic layers to be used:
10 Solid Model
11 - 50 Sketches, Generator Curves
51 - 99 Datums
122 Flat Pattern
125 Flat Pattern Dimensions
240 Dimensions
241 Utility Symbols (Centerlines, Intersection Points, etc.)
242 Notes, Labels


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[JohnRBaker]

Sorry, when I speak I tend to add emphasis to my words, but when I type, I have limited tools, capitalization being one of them. My use of caps was just to make a point, not as a reaction to anything that you typed. And for the record, I never worked for United Computing, but we were a customer of theirs before they were finally absorbed completely into McDonnell Douglas and the United name disappeared in late 1979. I started to work for McDonnell Douglas in August of 1980.

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[TheTick]

there's hidden layers beyond 256? Spooky and intriguing...

 

[jerry1423]

I also noticed many places have layer 61 for datums.

Jerry J.
UGV5-NX1961

 

[3DDave]

I started at McAir division in May 1980. At the time it was interesting that the aircraft side had nothing to do with UG, making it difficult for UG sales. Seeing the company that sold it didn't use it in the town they sold it from wasn't a great draw. Not sure when the UG guys finally pushed it internally to Saint Louis but McAuto seemed like a thorn in the side to McAir - the old-timers didn't much like the arrangement, but it seemed like a lot of companies were running in-house IT as an independent contractor with monopoly pricing status.

The company I went to after McAir had the full UG button box experience in the manufacturing end, but engineering stuck with Computervision as they had a PC board layout system. The tie was broken by manufacturing going Mazak and engineering going Pro/E. We did invite the UG reps in but they were strong sellers of Pro/E as were the Schlumberger guys.

Oddly - CV had 255 layers; Pro/E started with 32 numbered layers. Eventually PTC realized that "layers" was a limited and not helpful concept. They instituted a more generalized system of named lists, though they kept the "layers" designation in menus. Named lists freak many users out; they are flexible and self documenting but many users were unable to cope with the idea that an item could be on more than one list at the same time.

Small wonder that numeric layer designations would last so long.

 

[SDETERS]

yeah we have had issues with zero length lines getting put on layer 257, this turned our drawings from megabytes in size to gigabytes in size. Luckily we have a program that deletes all of the zero lines off of layer 257. One of those hidden layers. ha.

 

[JohnRBaker]

Yes, over the years there was a running debate about how did we get so many 'collector' schemes, Layers, Groups, Blank/Unblank, Assemblies, Reference Sets, etc. Several times there were proposals to scarp them all and come-up with a single, flexible scheme that could replace most of the legacy schemes, but each time when we looked at how we would transition existing part files to say nothing of customer's custom applications, we could never justify both the expense and the hassle.

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Toost]

If i remember things correctly, Sketches and datums came in as new object types in UG V8 with the UG/Concept module.
This was probably not seem by that many since it was an addon module to Unigraphics. ( -which probably was a good thing since the sketcher was "limited", I remember us trying to constrain a triangle...)
UGV10 which was a big change in all aspects of Unigraphics introduced parametric modeling, and sketches and datums, to all users.
I remember seeing the Layer 21 etc in the then training manuals for NX. I have always thought that these numbers came from the training material writers.

Regards,
Tomas

Never try to teach a pig to sing. I wastes your time and it annoys the pig.

 

[TheTick]

Layers are a mystery to most new users. They've been deemed obsolete, but they still have important uses, especially for managing large subassemblies where one does not have write access to said subs.

 

[JohnRBaker]

In the beginning, Layers were used both for Drafting and for managing the early Assemblies since the concept of Assemblies & Components, where an Assembly was simply a set of references to other Part files, was not introduced until Unigraphics II version 4.0, that was released in November 1986. After that, most people tended to use Layers mostly to manage Drawings. Some still used them for separating construction geometry from things like Surfaces.

With the introduction of Solid Modeling, particularly with UG 10.0 and the use of Sketches, more people started to use Layers to separate construction geometry, but now from both Surfaces and Solids. However, I personally started to use a much simpler scheme, using Blank/Unblank, particularly when we introduced functions like Reverse Blank, where is was easy to flip all of the Blank/Unblank statuses, so that you could then 'Blank' the stuff you wanted to turn back on, and then Reverse Blank again. We later 'automated' that by introducing the Unblank Selected function. For me and many of the people who adopted this approach, we just separated the world into what you could see and what you could not see (which is one reason we later changed the name of the Blank/Unblank function to Seen/Unseen). For us, at least when doing Modeling, Layers were considered as being even more archaic. And then we eventually automated this further by adding the concept of managing the visibility of Sketches when they had been used to create a Surface/Solid Body, reducing the usefulness of Layers even more.

Finally, from our (R&D) point of view, while we considered Layers as an old and outdated 'collection' scheme, we decided rather then try and do away with Layers, we would simply introduce new approaches which would effectively obsolete them, but would leave them in place to cover legacy usage. Granted, this violated one of the primary rules of software development, "You can't make something simpler by adding to it.", but we really had no other choice. We hoped that people would gravitate to the newer, more automated schemes and simply leave the older functions to die out from lack of use (like that was ever really going to happen ;-)).

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Toost]

The problem with using show/hide ( =blank/unblank) instead of Layers comes specifically when one does surface modeling, having several hundred similar splines in hidden mode and one needs just these n splines for the next step is not fun. it can be pretty nasty too using layers but it's a little better.

Regards,
Tomas

Never try to teach a pig to sing. I wastes your time and it annoys the pig.

 

[jerry1423]

I agree with Toost.
I think it is a good practice to use hide/show for temporary manipulation and layers for permanent management.

Jerry J.
UGV5-NX1961

 

[mmauldin]

My biggest use for layers is controlling what geometry is seen in each view in drafting by using "Visible in View". If there is another way, I'd love to hear it.

 

[cowski]

@mmauldin,
If you are using "visible in view" to hide components, you can use "hide components in view" instead.

www.nxjournaling.com