Notes on the June 2006 Meeting

Mark welcomed all to the first meeting in the new RMIT venue and especially the presenters Chris Needham, ImaginIT and Ian Hunter. The new venue is well set up and meets our needs, although car parking in the street is difficult to find at 6 o’clock. Next month, we’ll start the meeting at 6:30 to see if that makes life easier.

Tables, Fields and Hatching Improvements
Chris Needham
Chris presented a “leftover” session from last month, but a tasty one nevertheless! He covered some of the features which have been introduced or enhanced in the newer versions of AutoCAD.

Tables have been around in AutoCAD for a while now – they first arrived in AutoCAD 2005. To draw a table, first make sure that you have a suitable table style defined. These are a bit like DIM styles. The default size of table elements is assuming that they are to be drawn in paper space, or at least in a drawing whose plot scale is 1:1.
In AutoCAD 2006, you can reference cells by rows and columns, which opens up the possibility of using formulas to calculate the contents of other cells. You can now inert blocks in a table cell as a graphic image. This is useful for creating a legend of drawing symbols. You can even put fields in cells which can, for example, contain polyline areas for a live room area schedule.

Fields too, have a range of formatting options like m2 instead of mm2. You can then generate a live updating schedule of areas in the drawing. If you’re familiar with the way that Microsoft Word handles fields, then you’ll be right at home here. Fields really come into their own when used with the Sheet Set Manager, but that’s a whole topic for another meeting.

Hatching has been much improved in later versions. There’s a new system variable called HPGAPTOL that controls what size gap in the hatch boundary will be covered in the hatching. Still it does tend to get confused by arcs and other objects which “touch” the hatch area. Sometimes it’s still better to draw a polyline boundary in a no-plot layer and just use that to generate the hatch.

Hatch origin used to be controlled by the SNAPBASE system variable but now there’s a new one called HPORIGIN. You can easily set the hatch origin in the hatch or hatchedit dialog box. Osnaps can be set to ignore hatch objects if you wish. Find this under “Drafting Setting” in the Options dialog. Other recent enhancements include the ability to trim (but not extend) hatches and to re-create boundaries.

There have been a lot of new system variables introduced recently. Have a look at the list of system variables in the AutoCAD 2007 help file. Spend five minutes per day here and in no time you’ll be an AutoCAD power user!

AutoCAD Mechanical
David Morgan and Kent Matthews of ImaginIT.
David introduced himself and the company and explained the basic relationship between the various Autodesk mechanical products. They are resellers of mechanical products including AutoCAD, AutoCAD Mechanical, Mechanical Desktop and Autodesk Inventor.

Kent is a contractor working mainly in Inventor, but is presenting AutoCAD Mechanical tonight, so it’ll be interesting to see how he gets on with a major software program which is relatively new to him. He opened a drawing with a feature tree. This is something you don’t see every day in vanilla AutoCAD! They’ve beefed up the standard xref command to take heed of the mechanical features of the model. You can structure your models and assemblies with a mixture of local and externally referenced objects. This is a facility which is lacking in many 3D CAD programs. It gives you a lot of freedom in constructing your model. One neat way of doing this is to do your models in Inventor and then bring them into AutoCAD Mechanical to generate the 2D documentation.

The question was asked: Why don’t you simply do it in 3D all the way? There are a few good reasons, but one is that it’s simply a marketing response from Autodesk to the fact that many engineering drawing offices still prefer 2D design. This may be due to the steep 3D hardware requirements, increased productivity in simple parts or simply inertia. Whatever the reason, there’s still plenty of demand for a slick 2D mechanical drafting package.

Slick’s the word, too. Kent is happy to admit that he’s a novice in AutoCAD Mechanical 2007 – he only loaded it today – but he made a creditable attempt at drawing a shaft using the built in shaft generator. It was interesting to see the method of generating a shaft that a novice takes. The “wrong turns” that Kent took were in fact most instructive and generated a lot of healthy audience participation to put things right. This sort of demonstration can be more valuable than a smooth “canned” presentation where everyone falls asleep!
The big difference between AutoCAD Mechanical and vanilla AutoCAD is that you’re drawing “parts” rather than just dumb lines. You can manipulate these parts by moving, copying etc. yet keep track of their attributes. Even though it’s only 2D, in many situations it’s faster than trying to model everything in 3D.

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