Archive for May, 2009

Reviewing boundary conditions

Thursday, May 28th, 2009

Thank you, Richard Wand (MJ Engineering – for showing this cool trick!! And thank you Tony Tsao (SolidWorks Corporation) for reminding me to blog about this after the Simulation Tips and Tricks Webinar!!

In numerous instances, I have had the need to revisit some of the conditions that I set up on a simulation study. For instance, going back and checking what I applied on one bolt!! Or checking the value of a pressure load that I set up on the model. Usually, the quickest way to do this would be to right click on the item in the simulation tree, and select Details. This would pop-up a window that shows the definition of that item.


What is cool is the fact that you can lock this pop-up window down using the push-pin on the top right corner of the window.


Thereafter, clicking any entity on the simulation tree would bring up its corresponding definition in the pop-up window. Try doing this by walking through some of the items you have already set up in your Simulation tree (such as connections, external loads, fixtures, etc.).

Another way of getting  a quick summary of any portion of the pre-processing is to generate a report and choose to only include a specific item (such as external loads) in the report. Publishing the report would list out all the external loads that were setup in the study.

Remember: Reviewing boundary conditions is a necessary step before running the analysis, and when troubleshooting erroneous results!!

Vikram Vedantham

Simulation Product Manager 3DVision Technologies

Back, then to the Future

Wednesday, May 27th, 2009

Mail Call!

Dear Engineering Data Specialist Man

I am working with a customer who is constantly changing his mind -as a result I am nearly losing mine! Several times now he has asked me to revert to a previous version of a design and make new modifications from there! I am using SolidWorks Enterprise PDM, is there an easy way to accomplish this?

M. McFly

Dear Marty,
Logically you could make a copy of the older version on your desktop, check out the file then overwrite the file in your local cache with the version on your desktop. Actually there is an even easier way:

  • Check out the file
  • “Get” the older version (you will be notified you are going to write over the version in the cache, that is okay, say “yes”
  • Make the modifications you want, when you check in the file it will become the new next version!

It feels a bit weird getting an older version of a file while it is checked out but it is a lot easier to understand than a flux capacitor isn’t it?

Yours in engineering data service,

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

One Milllllllion Licenses!

Wednesday, May 20th, 2009

SolidWorks has hit ONE MILLION LICENSES! I still have a really nice polo shirt that says “200,000 licenses” on it from my second year with 3DVision! Needless to say, it is as obsolete as my Bengals T. J. Houshmandzadeh 84 jersey (Yes, I had to look the spelling up on Wikipedia… hope they were right!)

This is a big milestone for any CAD company. It means they did something right early, continued to innovate and develop, and listened to the user base who keeps coming back for more.

I have been around the SolidWorks community since release 97+. Anyone been around longer? Think you know the history of SolidWorks? Play the Trivia Game here(contains sound)! Watch a personal thank you from CEO Jeff Ray and founder Jon Hirschtick here.

What do you think are the most important things SolidWorks needs to do to if they want to keep this momentum? Submit a comment below…

Dr. Evil

Dr. Evil (aka Scott High)
Technical Services Manager
3DVision Technologies

Scott High

Technical Services Manager 3DVision Technologies

Keeping up with the Joneses

Tuesday, May 19th, 2009

The following is an interview with Jimmy, our top gun designer from Friday’s upgrade zone episode.

Engineering Data Specialist Man: You have a reputation around here as the go to SolidWorks guy, yet we couldn’t help but notice you did not use any of the enhancements offered in the new upgrade what happened?

jonesesJimmy: I always try to attend the 3DVision “What’s new” presentations, but this year I wasn’t allowed to go. Isn’t it interesting that companies offer tuition reimbursement but won’t let you take a half day to attend a What’s New presentation? They’d pay for me to take a pottery class (as long as I get a “C” or better) but they won’t help me keep my SolidWorks skills current?

EDSM: [Sigh] Some companies don’t understand that there is a cost to maintaining talent. Do you remember if your job description mentions that one of your job responsibilities is to keep up with technology? I know that is a typical statement at most companies.

Jimmy: I think it does, I always figured that was just something they put in so they could fire me if they ever needed to.

EDSM: Ahh…they have you paranoid, looks like your boss is doing his job; however that little loop-hole statement is a good thing! It is your ticket to improving yourself on company time.

Jimmy: I suppose that is true, but if I miss the “What’s New” presentations how can I keep up?

EDSM: Yeah, it is difficult without being able to attend the “What’s New”s -I always think of them as the best continuing education opportunity around, but they aren’t the only tools at your disposal. SolidWorks World, Technical Summits, the SolidWorks forum, SolidWorks blogs, the “What’s New” document (found in the help section of SolidWorks), and even trade magazines are good tools at your disposal. Remember as fast as technology changes, if you don’t improve, you are falling behind. Try to set aside time each week to devote to “keeping up with technology”. At the very least ensure you go through the “What’s New” document, even if you don’t think a chapter directly will be used in your company. You might find a new approach to an age old issue in your company.

Jimmy: I’ve been thinking of attending one of the SolidWorks user group meetings do they help?

EDSM: I’ve never attended one where I didn’t at least learn something. Besides, you cannot go wrong with free pizza!

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

The SolidWorks Upgrade Zone

Friday, May 15th, 2009

What you are about to read may surprise or even shock you. You are about to enter the SolidWorks Upgrade Zone.

spinyTake this man Jimmy. Jimmy is the top gun engineer at his company. Last night Jimmy’s IT department upgraded his SolidWorks installation from SolidWorks 2008 to 2009. Let’s watch to see how much faster Jimmy is with the new upgrade.

I see Jimmy is working with weldments, but not taking advantage of the new 2009 group feature. Interesting –I am sure it would have saved him quite a bit of time there. Let’s watch him as he works with sheet metal. Wow, he is still using the same techniques he learned when he took the sheet metal class four years ago! Now let’s watch as he works with some large assemblies, I am sure the new Speedpak technology will be a huge time saver! Wait! He isn’t even using it! Oh the calamity!

So here we are at the end of the day…let’s bring up the tote board to see how much time Jimmy saved with the upgrade! [Drum roll] Two minutes! Wait, only two minutes?! How could this be? Jimmy’s company has been paying maintenance for a full year to only gain two minutes? Granted that Engineering Data Specialist guy provides excellent support, but still -only two minutes? [Rod Sterling & Jerry Lee Lewis walk off the set shaking their heads.]

What you just saw here is going on all over the world right now. This is the time of year many companies upgrade their users to the new SolidWorks version. Sadly, for many, that is where the upgrade ends. If the users are not given an opportunity to learn how to use the new version, they will continue to use SolidWorks how they were originally taught.

An upgrade requires two steps. You need to upgrade the machine and the users. If you only upgrade one of the two your return on investment is not as good as it could be. Few users learn the new performance enhancements on their own.

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

Circular References – The Cure

Monday, May 11th, 2009

As my Great Aunt Eleanor always says: “An ounce of prevention is worth a pound of cure, stop bothering me while I am trying to sell my WoW gold on eBay!”

While I am not entirely sure what all of that means, she certainly is correct if she is talking about circular references. Preventing circular references from being created is much easier than trying to find them.

Going back to last Monday’s quiz, the first puzzle’s problem could be avoided if you remember this quote: “Always mate before you relate”. [I'll wait until the sophomore class stop giggling.] What this means is if you always fully mate the part in your assembly before you add any external relationships, a circular reference of this type will never happen. If you think about it, this is your design intent anyway. The position of the part is what you care about, the mounting fastener holes need to follow the part, not vice versa.

I don’t have a cute saying to prevent the second puzzle’s problem. The trick is to always ensure you mate your parts with design intent. Adding your parts to your assembly one at a time in a logical fashion will make this task easier. “PartA” is a fixed part. “PartB” bolts to “PartA” so fully add mates between those two. Next add “PartC”. “PartC” is located via “PartB” so only add mates between those two parts, don’t add any mates between “PartC” & “PartA”. Try to define the location of a part with only one other part. Though it is not always possible, this method reduces accidental circular references and makes an assembly easier to work with if your design intent ever changes.

Bottom up design and horizontal modeling techniques are also methods that reduce the likelihood of accidentally creating a circular reference.

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

Circular References = Termites

Thursday, May 7th, 2009

Circular references are the termites of the CAD world. You might not know they are there, they might not cause any real damage, or your house could fall on your head.

Your first clue that you have a circular reference is that change you make don’t affect your models as you think they should or you see terrible performance in some assemblies but other assemblies seem to be just fine. The AssemblyXpert is supposed to help you find them, but it didn’t find issue with either of the two assemblies in the quiz -so apparently it has some weaknesses. (I do have an SPR for these two, so there is hope for the future.)

assemblyxpertWithout the AssemblyXpert, you are pretty much left to manually find the problem. I typically suppress every part but the first fixed part, then unsupress each part one at a time keeping track of every mate and external reference as I go. Move the parts (sometimes temporarily suppressing mates) check your design intent…is everything working as it should? Then, if you are lucky, when you get to the part that contains/or is causing the circular references you’ll notice things aren’t quite right -fix the issue and then hope you are done. Else start the process over again!

Debugging circular references is a skill, and you will get better at finding them with practice.

Not a very rosy picture is it? Nope. That is why an ounce of prevention goes a long way which brings me to my favorite topic “Best Practices”!  …

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

Circular References – Answers

Tuesday, May 5th, 2009

What did you think of Monday’s quiz? I was surprised by the responses I received, only about 1/2 the people found both circular references.

CircularRefs.SLDASM is a typical problem I often find when a user attaches a purchase part to his assembly. (i.e. mounting plate) Think of the yellow block as the mounting plate and the red block as the purchased part. The red block has the hole and the yellow block has its hole positioned via an external reference back to the red part. (The logic being you always want the hole to line up with the purchased part.) However, notice the red block is positioned by the Concentric1 mate! Thus the position of the red block is defined by the position of the hole, yet the position of the hole is defined by the red block.

Image for second puzzle

Image for CircularRefs2.sldasm

CircularRefs2.SLDASM demonstrates a mating issue. Through mates, the yellow block defines the position of the red block. Through mates again, the red block defines the position of the blue block, and lastly through more mates the position of the blue block defines the position of the original yellow block!

Both of these examples aren’t terribly bad, yet there are very few parts here. Imagine (and I have seen examples of this) where there could be many parts involved in creating the circular reference. It works like a big chain reaction.

There is a third common circular reference type that I did not show in either of these examples. Equations (in both part and assembly files) can be an issue. One dimension defines the value of a second which in turn defines the value of the first. If you are an equation fan, you have to watch out for these too.

Lastly, you can have combination of these three scenarios: The mate defines the reference that defines the equation…oh the problems can go on and on!

Are circular references bad? Yeah, typically. Assemblies that contain them are difficult to change, and parts don’t update as you expect them to –sometimes they don’t update at all or they change for no apparent reason! Not to mention that it can bring your PDM package to its knees and kill your SolidWorks performance. Bad, bad, bad and bad.

Have I frightened ya? I hear you cry:  “Is there an easy way to find circular references??” Fine, I’ll tell you…..after the break….

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

Transition Layers in Mesh Control

Tuesday, May 5th, 2009

While practising for the upcoming Simulation Premium training class this week that I am going to teach, I came across an instance where I wanted to control the number of layers for the growth of mesh size. Prior to 2009, the Mesh Control utility in Simulation permitted the user to specify the number of layers to grow from the local element size to the global element size. This functionality is gone in 2009. That confused me as much as some of the attendees at the COSSUG meeting two weeks ago in Columbus, OH.

Well, the solution is tricky to get to, but is available in 2009!!

Apparently, the two options available now are the desired local element size, and a ratio called a/b. The ratio was defined previously as the desired Aspect Ratio (or a measure of skewedness of the elements). In 2009, the definition has been re-written as the ratio of the element size in one layer to the element size in the preceding layer.

Now, that got me thinking about how to back-calculate and hence control the number of layers. So here is the solution:

The general expression that dictates mesh sizes can be stated as:


Here is an example:

Suppose I want the local size to be 0.2mm and the global size to be 0.3456mm, and the number of layers to be 3. I can calculate the a/b value by substituting these numbers into the above equation. I end up with a value of 1.2, which would yield the desired result in the mesh. If I want the number of layers to be 10, I can re-calculate the equation, and the new a/b value is 1.056.

As a generalized observed rule, the smaller the a/b value, the slower the growth rate.

So pull out those calculators, and start punching away!! The functionality is still there.

Vikram Vedantham

Simulation Product Manager 3DVision Technologies

Circular References Quiz

Tuesday, May 5th, 2009

You think you are hot stuff eh? You’ve gone through all the training classes -been studying for the CSWP, think you got SolidWorks licked? I have two words can make even the most seasoned SolidWorks user cringe…”circular references”.

I’ll give you a minute for your breathing to recover. <Sorry> You come to the 3DVision blog to be entertained and maybe learn something, and I spring that on you.

Circular references are a rather advanced topic because they are difficult to find and fix, yet sadly it is beginner users who get them the most often.

The Engineering Data Specialist’s handbook describes circular references as: When one thing defines another and that second thing in turn defines the first thing. [Hey, we work with data all day, we don't need to speak English very goodly.]

This zip file <CLICK HERE> contains two assemblies. Each assembly contains a different type of circular references. Here is the quiz. Open the two assemblies and see how long it takes you to find each problem. We’ll discuss these in future posts.

Jeff Sweeney

CSWE Engineering Data Specialist 3DVision Technologies

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