Dimensional limits related to an origin

In SolidWorks 2007 drawing mode, the ability to change the size of individual dimension arrows (so that they were different than the drawing) was limited to a tricky use of favorites.   Starting with SolidWorks 2008, that situation improved.   SolidWorks now allows the user to set the size for individual dimension arrows.  For me, using arrows of a different size from the drawing default was only required once in the past.  However, I recently had the need to use this function for dimensioning limits from an origin. This is a special kind of dimension where the tolerance of a dimension is set between two features but applied in only one direction.

From paragraph 2.6.1 of the ASME Y14.5M-1994 standard:

In certain cases, it is necessary to indicate that a dimension between two features shall originate from one of these features and not the other.  The high points of the surface indicated as the origin define a plane for measurement.  The dimensions related to the origin are taken from the plane or axis and define a zone within which other features must lie.

The origin of such a dimension is shown by replacing that arrow with a circle.

Meaning

This is where we get back to talking about SolidWorks.  You can change the shape and size of the arrows on one or both sides of a dimension.  The problem is that once the dimension arrow is changed to a circle, its size cannot be adjusted. This means that if the circle is too small (as it likely will be) the size must be changed to the arrow before switching it to a circle.

The following are the basic steps to establishing a dimensional limit related to an origin on a drawing in SolidWorks 2008 or higher.

Instructions 1 and 2

This following chart will then pop up at that location on your drawing view.

Pop up chart

3. Select Size, to bring up the next window.

Arrow size changing window

4. Deselect Use document arrow size and edit the arrow width.  Accept by choosing the OK button.

Enter width

No, you aren’t done yet.  There’s more.  Remember, earlier I said the situation was easier.  I didn’t say it was easy.

More steps

Again Again

7. Select the fifth item down on the pop up chart, which is the circle at the end of the dimension line.

Final Product

After all of this, you’ll finally have a dimension that establishes its tolerance from an origin per ASME Y14.5-1994 paragraph 2.6.1 and figure 2-5.

UPDATE: Newer releases of SOLIDWORKS will allow you to apply a size directly to the circle arrow. So, although the above instructions still will work, there are some extra steps that are no longer necessary.

SolidWorks headquarters

The visit to SolidWorks headquarters in Concord, MA has been very eventful.  This has been on busy trip.  The schedule has been full from each early morning to evening.  The SolidWorks bloggers definitely have a lot of material to work from in the up coming months.  There is a lot of detail on already available information, as well as a ton of info about what’s to come soon. One thing that is coming up that SolidWorks Corp is very proud is Sustainability and SustainabilityXpress.  There’s also a lot of exciting improvements to SolidWorks 2010 that make it worth a look when it comes out.  More to come, including “secret” photos of the SolidWorks operations.  😉  For now, I’m heading out to my long flight back home.

Lexington, MA

Lexington is a small community just outside of Boston on your way to Concord in Massachusetts.  It’s one of those places visitors may not expect to find themselves when coming to this grand state.  It has a quaint downtown with simple flare.  SolidWorks Corp (aka DS SolidWorks Corporation) has invited many of the SolidWorks bloggers to this locale for what looks to be an all-you-can-eat buffet of their product offerings in the Concord headquarters, with glimpses of what is to come for SolidWorks 2010.  This is my first visit to Concord, MA and to the SolidWorks Corp headquarters.  There’s a few returnees to the headquarters in our group of attendees.  Every attendee has been a SolidWorks Corp guest to press events in the past.  This event is technically not a press event (being just for SolidWorks bloggers); it is my first time I am a guest of SolidWorks Corp at an event outside of SolidWorks World.  I’m a excited about that and the prospect of being able to see the SolidWorks Corp headquarters.

It’s All Over!

When “All Over” is applied to a Profile of a Surface, it pretty much defines the entire shape of a part in every direction.

ASME Y14.5M-2009 has been out for a little while now (after almost a year’s delay).  There are significant improvements and clarifications.  One addition in particular caught my attention, the ALL OVER symbol.  When applied to a Profile of a Surface, it pretty much defines the entire shape of a part in every direction (not just ALL AROUND which applies to the profile of a surface along a particular plane).

The symbol is either a double circle at the vertex of the associated bent leader, or the words ALL OVER placed immediately below the feature control frame.

ALL OVER symbols

The symbol indicates that a profile tolerance or other specification shall apply all over the three-dimensional profile of a part. It is applied as “unless otherwise specified” to allow for other existing dimensions and tolerances to take precedence.

ASME Example

The advantage of using this symbol is that it provides control of surfaces over an entire part without regard to part orientation, thus allowing us to directly reference the CAD model as basic and fully controlled, while still detailing critical dimensions and tolerances.  This may help companies better parts where they rely on the CAD model to provide complete specification.  In fact, where a CAD model is declared basic, companies may be able to effectively place the Profile of a Surface FCF with the ALL OVER symbol right into their drawing title blocks along side other tolerancing information.

June SW Legion Contest analysis (Part 3) – No July Contest

There will be no July SW Legion contest.  I’m planning on something a bit bigger for August and September, so for now, I’ll take a month’s break from contests.  June SW Legion Contest was very successful. As promised, I’m going to discuss some of the variety of entries. There are many ways to approach modelling in SolidWorks.  This the June SW Legion Contest is proof of that.

One of the more interesting scalene ellipsoid model entries was technically not a solid model.  Rather, it was a Surface-Loft, with three sketches (each with an ellipse in the proper proportions), by Ian Vivero.  This was the most functional of all scalene entries because it effectively used equations to drive the shape with one dimension value.

Of the scalene submissions, Matt Lombard’s was the simplest, with one Loft and one cleaver 3D sketch.  The problem is that I was not able to confirm its scaleneness.  The shape did not fall exactly along ellipses in all three directions.  This entry relied on the default SolidWorks choices for a lofted shape.  It was very close, however.

Two entries used exactly the same methodology: a simple revolve of a half circle that was then scaled in the appropriate proportions in X, Y and Z directions.  Very simple and cleaver.  These submittees were Cam Shute and Gary Liptrot.

Another cleaver entry that also had only three elements was by Arash Erfanian (unofficial winner who earned a CSWSP-FEA test).  This entry was one Sweep feature with one 2D sketch and one 3D sketch.

Other entries that were equally cleaver, but with more elements.  This included one entry that used another method with Surface-Loft and mirror features.

Two entries relied of the fact that I did not word my contest properly.  True to my word the one legitimate entry does represent the official winner of the contest, Sandeep Pawar (who chose a CSWP test as the prize).

Enhancement Request

So, I am teaching the students how to reuse pre-existing data in SolidWorks.  The project is using a Truarc – E-Clip retaining ring. Cool stuff – Toolbox has the Truarc catalog to just drag and drop.  Toolbox Pull-down has the groove generator with the intelligence to select the correct groove size/feature for the Truarc E-Clip by having the user just select the shaft surface. Awesome stuff right?  That is until you realize that the dimensions, relations and tolerances have to be applied manually.  All the information is there so why doesn’t SolidWorks just dump the info in.Here is the best part, up until that point the students think I am God handing out the solution that they could have used the semester previous.  “Oh man!  We could have used this on 4 project last semester”  Then we DEFINE the groove. “Why would I want to use this tool?” That is the outstanding question of the year!  Why have an incomplete tool.  It ends up being 3 times the work to define the groove than if you just did the revolved cut. No matter if your company is model centric or still uses drawings the size/location dimensions and tolerances still need to be there.  Please jump on this bandwagon and complete the enhancement request to finish this tool.  In theory it is a huge time saver and could potentially help designers and engineers from making mistakes about o-ring and retaining part numbers, sizes, dimensions and tolerances.  –Chris MacCormack