Foreshortening Dimensions (Radial, not linear)

[Updated to address changes in SOLIDWORKS 2016]

SOLIDWORKS provides for the foreshortening of diameters and radii dimensions.  Older releases of SOLIDWORKS didn’t allow for the foreshortening of linear dimensions (or clipped dimensions), except in break views where both ends of the dimension are visible.  When I first encountered this limitation years ago, I was concerned that SOLIDWORKS developers just simply overlooked this functionality.  After all, if one can foreshorten a radius, then why not a linear dimension?  I was even sure I could find examples of this already being done on other drawings in detail views.  I was trying to use an open ended dimension line with double arrows on the open end.  I may have actually used this method a couple of times back in my AutoCAD days.

But what didn’t SOLIDWORKS support this for many years?  The lack of foreshortened linear dimensions can be understood by reading ASME Y14.5M-1994 paragraph 1.8.2.2.  This paragraph established the foreshortening of radii.  Its title Foreshortened Radii seems to preclude these methods for linear dimensions.  But why?

The clue is the intent.  1.8.2.2. states that if the center of a radius is outside the drawing or interferes with another view, the radius dimension may be foreshortened.  Strangely enough, paragraph 1.8.2.2 does not specifically describe the just how foreshortening is demonstrated, other than to say the dimension line is radial to the arc.  It does reference a figure that shows radii centers repositioned with zigzagged radial and coordinate dimension lines.  The key is that the center of the radius is still within view.  The dimensions have known termination at both ends.

Allowed foreshortening of radial dimensions

There is an issue with using this methodology on any dimensions where the termination of both ends is not clearly shown.  Without both ends of the dimension in view (or known through some other way), there is no established way to determine where the dimension’s open end terminates.  It is an incomplete specification.  In other words, if I have a detail view and attempt to dimension to a feature not in that detail, the fabricator does not know the location of the other end of that dimension.  SOLIDWORKS previous limitation was not really a limitation after all.  It follows the drafting standards in a very logical way.

Disallowed foreshortening and diameter forshortening

Another thing SOLIDWORKS allows is the foreshortening of diameters.  Although this is not directly supported by the standards, it is common practice.  Unlike the foreshortening of linear dimensions, foreshortened diameters make sense since the other end of the dimension is known, even if it is not shown.  I’ll address foreshortened diameters in more detail a future article.

As of SOLIDWORKS 2016, foreshorten of linear dimensions is supported without restriction.  This was added for customers who still need methods to clip dimensions regardless to the issues mentioned above.

“Brand New Car”

In case anyone is in doubt, but not over finances, right now is a GREAT time to buy a car.  I cannot overstate this fact.  With the economic woes causing our system to collapse all around us, there are many opportunities for which to take advantage.  Stock market is one, if you don’t mind the rollercoaster ride.  Another way is in using one’s buying power for the big ticket items (cars in particular, but yeah, I’m sure boats and such are going for huge discounts too).

I recently traded in my old 2003 Acura TL Type-S for a 2009 Pontiac G8 GT.  As I began on this strange move months ago, I got asked “trade in an Acura for a Pontiac?”.  Yes, without reservation.  I waited to make this exchange until the end of Sept, and I’m glad I did because I got great pricing.  (OK, the reasons why I readily dumped my Acura for a Pontiac are best covered some other time.  I’ll just say that no one asks why once they see my G8 GT and ride in it.)  Anyway, the point is, right now is a great time to get some really great deals on the cars.

This isn’t a message to tell people “Hey, go out and support the American economy.”  This is a message saying “Now is the time to strike; to get the really great bargains.”  The consumer advantage is not limited to GM.  All the car companies are in pain right now.  As I shopped around in recent months, many of the dealers put on a brave face, but there is an air of desperation.  I guess a better way to put is that they are willing to actually deal.  No more dealer mark-ups.  I’ve actually seen quite the opposite.  Some brands are selling 2008’s for WAY under even the invoice price (prolly close to what is actually paid by the dealer).

Of course, if you invest your money, you might score a 3.0% yield CD, which is running at about 1/2 the current inflation rate.  You can try to time the stock market, but much bigger money is likely timing you instead.  If you are going to lose money, you might as well enjoy the ride (literally).

SolidWorks World 2009 is coming together

If interested, I encourage everyone to check out the SolidWorks World 2009 website.  Included are details about SolidWorks World 2009 (SWW09), of course.  Yes, it’s that time of year already.  Time flies by, doesn’t it?  The first announcement of Breakout Sessions and Hands-on Sessions is now available for viewing too. This is useful for planning attendance and maybe even in justifying the trip to one’s boss.

As usual, there are diverse topics covering the basics to advanced ideas, and the abstract to the very specific.  There is already a large selection to choose from.  Here’s the list of the categories.

CAD Administration
Data Management
Design Automation
Design Validation
Education
Modeling Essentials
Productivity Tools
Customer Success/Designing Better Products
Tips and Tricks
Design Communication

And, here’s a quick snap shot of just a few of the actual sessions:

  1. Surfacing for Beginners
  2. Using SolidWorks to create a greener World
  3. Connecting SolidWorks Enterprise PDM to your ERP system
  4. Saving time using Smart Components

From the looks of what scheduled so far, this promises to be a very educational conference.

Measure that Mate (Why are results different?)

I was recently asked,

“I did a check where the distance mate value and the measurement for the same features shows two markedly different values.  Have you ever seen anything like this?”

Distance Mate Result

This individual wondered how it was possible that his measurement of two associated features was different than the dimension he entered for the distance mate assigned to those two features.

Measurement Results

My reply was pragmatic.

“Without seeing the model directly, it’s hard to confirm the error.  However, I have found that whenever SolidWorks gives me a number and it doesn’t make sense, it is due to something the user is doing or some misinterpretation of the data.  This causes me to try to investigate when such issues arise by first considering what the user is doing.

“In this case, I’m assuming you are measuring from the center of the circle to the flat face.  However, I notice that your mate is set up face to face. I’m guessing SolidWorks is mating your hole based on the closest point of the circular face, and not the hole’s center.

“To fix this, use the temporary axis of the hole as the selected entity for your mate instead of the hole’s face.”

This individual followed my advice and was able to eliminate the apparent discrepancy.  In general, it is a good idea to check look at how SolidWorks (or any software) functions in order to understand why something is happening.