Parametric modeling - Part 2

Geometric Constraints

The first panel on the left side of the Parametric tab is for the tools that create and modify geometric constraints. These are the relationships that are applied between two objects, points on objects, or between a single object and the coordinate system. In simple terms it works like an object snap that stays persistent throughout your design.

The middle sub panel on the Geometric constraints panel contains the commands that you will use to apply the constraints to objects in your drawings. These can be accessed from this location on the ribbon or with the GEOMCONSTRAINT command. There are twelve to choose from, we’ll cover each of them.


Coincident - Constrains two points on two objects together. A constraint point on an object can be made coincident with an object or a constraint point on another object. When the cursor hovers over the constrained point, the constraint bar to the right is shown.


Colinear – Constrains two or more line segments to lie along the same line. Regardless of how the original line is moved or rotated, the Colinear line will move to match the new location.


Concentric - Constrains two circles to the same center point. This also works for arcs and ellipses. The result is the same as that of a coincident constraint applied to the center points of the curves. Moving one of the circles will move the other with it, much like a block.


Fix - Locks a point or curve in position. The fixed point can be on an object, or a point in relation to an object, like a center point of a circle for example. This command may be a let down for those people who thought it might fix something in the drawings that doesn’t seem to work the way they wanted it to.


Parallel – Constrains two lines or polylines to be Parallel to each other. When one is modified the other will move to match it.


Perpendicular - Causes selected lines to lie 90 degrees to one another. Perpendicular constraints are applied between two objects and, unlike the Perpendicular object snap, these lines do not have to be touching each other when the constraint is created.


Horizontal - Causes lines or pairs of points to lie parallel to the X axis of the current coordinate system. Be aware when using this constraint that they are set to the axis in the coordinate system in which they were created. When another user coordinate system is active the Constraint bar icon (pictured below) will change to show that the current axis in not the one that the constraint was created in.









Vertical - Causes lines or pairs of points to lie parallel to the Y axis of the current coordinate system. Just like the Horizontal constrain these are set to the axis in the coordinate system in which they were created. When another user coordinate system is active the Constraint bar icon (pictured on the right) will change to show that the current axis in not the one that the constraint was created in.











Tangent - Constrains two objects to maintain a point of tangency to each other or their extensions. Tangent constraints are applied between two objects, those objects could be a curve (arc or circle) and a line or another curve.

A circle can be made tangent to a line even if the circle does not touch the line and a curve can be tangent to another even if they do not physically share a point.

Smooth (G2) - Constrains a Spline to be contiguous and maintain continuity with another spline, line, arc, or polyline. When the constraint is applied the endpoints of the curves to which you apply the smooth constraints are made coincident.


When two Splines are selected, they are updated to be contiguous with one another. This function is similar to using the JOIN command for polylines except the splines are not joined to be one object; they only behave as if they were one object.


Symmetric - Causes selected objects to become symmetrically constrained about a selected line. The function is similar to that of the Mirror command. Unlike other constraints where two objects are selected, with a symmetric constraint you must have an axis around which you will constrain the objects or points to be symmetrical.


This is referred to as the symmetry line. For lines, the line’s angle is made symmetric and not the endpoints. For arcs and circles, the center and radius are made symmetric not the endpoints of the arc.


Equal - Resizes selected arcs and circles to the same radius, or selected lines to the same length.

Parametric modeling

Parametric modeling

The biggest and initially the most intimidating new feature in AutoCAD 2010 is Parametric Modeling. You may be surprised to find that there is no actual Parametric command. That’s because it’s the name for a new set of tools that allow you to create geometric relationships between objects or restrict the dimensional properties of objects. The two different types of tools are referred to as geometric and dimensional constraints. That doesn’t sound that complicated now does it?

Well before you panic and pull out the old dictionary that you used to use to decipher what Dennis Miller said on Monday night football, relax. We’ll go through the tools and their usage in plain English and before you know it, you’ll see that it’s really not complicated at all.

All of the constraint settings and display options are handled by the Constraint settings dialog box. You can open it with the CONSTRAINTSETTINGS command. We’ll refer back to this command as we cover the different constraint functions and commands.

Another important feature that is used with the constraints are the Constraint Bars, these show which constraints are applied to drawing objects. The CONSTRAINTBAR command effects how the constraint bars are displayed. When constraint bars are displayed, you can pass the cursor over a constraint to view the constraint name and the objects that it affects. You can also control the display of constraint bars with this command or use the Show, Show All, and Hide All options on the Geometric panel of the Parametric ribbon tab.



There is a new Tab on the menu ribbon for the parametric modeling tools called the Parametric tab. This tab is broken down into three panels, each with a different set of tools that you would use for the different constraint functions. Over the next few posts we'll look at each separately.

Election page is open!

The AUGI Special Election voting page is now live, and will be open until July 12, 2009. I encourage all AUGI members to carefully consider the candidates and make your voice heard.

AUGI Board Candidate Forums are now open!

I'm very happy to announce that I was selected as a candidate for the special election for the AUGI Board of directors.

The Board candidate forums are now open. To link to the main discussion forums go here. To view my profile and see my responses to the questionnaire go to this page.

Since these forums are heavily moderated your questions will be reviewed before they are posted. If your question is denied or if you need clarification on one of my answers please feel free to contact me. Within AUGI you can send a Private message or you can me an email at augi.doggie@gmail.com.

Even if you only read the responses I still strongly urge you to vote when the polls open on June 29, 2009.

I'm also happy to announce that the much anticipated AUGI AEC Edge magazine has released it's first issue.

I'm happy to announce that the AUGI Training Program is offering some new courses this month. ATP Courses for June 2009 are posted online and start next week (2009-6-08). So it's not to late to sign up.

ATP246 - What’s new in Revit Architecture 2010 - This three part class is designed to introduce you to the new features of Revit Architecture 2010. If you are new to Revit, or a pro, this class will define the differences between the old and the new.

ATP250 - FIELD of Study - In this class you will learn what an AutoCAD Field is, what functions they serve, and how they work. You will also discover what Fields are capable of doing and their limitations.

ATP249 - What's new in AutoCAD 2010 Once again, each new year brings a new release of AutoCAD. This course will provide an in-depth look at the new features and enhancements in AutoCAD 2010.


To Register go to the Current ATP Courses page. Note: You must be a member of AUGI to register for ATP classes. Membership is free.

The best commands you're not using (Part 2)

Since my last post covering some of the old “new” commands that people aren’t using, ended with Dynamic input, it seems logical to continue on with some more of the same. Here’s a deeper look at some of the commands that you can use with the Dynamic input feature.

Object Snap Tracking

Object Snap Tracking helps you draw objects at specific angles or in relation to other objects. When you turn on Object Snap Tracking, by pressing F11 or clicking on Otrack on the status bar, it uses AutoCAD’s trademarked AutoTrack technology to create temporary alignment paths. This will help you create objects at precise positions and angles relative to a snapped object.

Object Snap Tracking works based on the current object snap settings. You must enable Osnaps before you can track from an object's snap point.

You can change the settings by clicking on Osnap in the status bar, right click and select the Settings option. There is a toggle, highlighted in the figure above, in the Object Snap tab that will also activate Object Snap Tracking.

In the figure below, the Endpoint object snap is on. You start a line, as you normally would, by clicking its start point. In this example, we will be selecting the corner of the wall as our acquired point.

Move the cursor over the other line's endpoint to acquire it. You do not need to click on it, simply let it hover over the point until it is acquired. Acquired points display a small plus sign, shown in the figure above.

After you acquire a point, horizontal, vertical, or polar alignment paths relative to the point are displayed as you move the cursor over their drawing paths. You can acquire up to seven tracking points at a time.

Polar Tracking

Polar Tracking snaps the cursor to specified polar angles. You can use polar tracking to display temporary alignment paths defined by the angles you specify. In 3D views, polar tracking additionally provides an alignment path in the negative and positive Z (up and down) directions.


Polar angles are relative to the orientation of the current UCS and use that X orientation as the base 0 angle. As you move your cursor, alignment paths and tooltips are displayed when you move the cursor over the specified polar angles. Use the alignment path and tooltip to draw your object.

For example if you click on the Polar button in the status bar, right click and select Settings. Set the Polar Angle Settings to a 45-degree polar angle increment, an alignment path and tooltip are displayed when your cursor crosses the 0 or 45-degree angle. The alignment path and tooltip disappear when you move the cursor away from the angle and reappear near the next angle.

These can be quite handy when using the object snap tracking and polar tracking together. You can acquire the object snap tracking point and track at a polar tracking angle from that point.

Conclusion

There is a slightly different feel to using these commands. When you’re drawing, the cursor will have a lot more information floating around it. But once you get used to the new look and feel you’ll find that these commands can be a huge help. Try to take a little time to check out; you might be pleasantly surprised at what you find.

The best commands that you’re not using

There are so many commands in AutoCAD that even the most experienced users don’t use a lot of the tools that are available. More often than not, I’ll show some of my AutoCAD users a command to make their work a little easier and the response is almost always “Wow, is that a new command?” Since it’s a new year, I figure this might be the perfect time to take a fresh look at some of the old “new” commands that a lot of AutoCAD users don’t always take advantage of.

Match Properties

Tucked away comfortably in the Standard toolbar is the Match Properties command, highlighted in the figure to the right. This command does exactly what the name claims; it matches the properties of a Target object to that of a Source object.

After picking the Match Properties icon, or typing MATCHPROP at the command line, you will be prompted to select a source object. This is the object whose properties you want to copy to other objects.

Once this object is selected, you can either select the target object or type S to open the Settings dialog. Settings allows you to pick which object attributes you want or don’t want copied to the target objects. By default, all of the properties will be selected. If you don't want a specific property or properties to be applied to the new object, use the Settings option to suppress the copying of that property to the new object. You can also choose the Settings option at any time while the command is running.

The properties are broken down into two categories, Basic and special properties. Basic properties are simply the properties that almost all objects in a drawing will have. The Special Properties will only apply to certain objects in the drawing, these are also selected by default when you first run the command.

Note: In versions prior to 2008, the Multileader toggle is not listed in the Special Properties section.

Dynamic Input

Dynamic Input is a powerful tool that provides a command interface near the cursor. This will help you keep your focus in the drawing area, and not looking down at the command window as often, ever second that you’re not looking at the screen is time lost.

The figure above shows the Dynamic Prompt, this allows you to type in commands without using the command window. Dynamic Input is not designed to replace the command window, but it will allow you to hide the command window to add more precious screen area for drawing.

When Dynamic Input is on, tooltips display information near the cursor that is dynamically updated as the cursor moves.

When a command is active, the tooltips provide a place for user entry. This is referred to as Dimension Input when drawing an object that requires a distance or angle. If a command requires a point or a coordinate input it is referred to as Pointer Input.

After you type a value in an input field and press the TAB button the field then displays a lock icon, and the cursor is constrained by the value that you entered. You can then enter a value for the second input field.

If you type a value in the first input field and press ENTER, the second input field is ignored and the value is interpreted as direct distance entry.


You can change the Dynamic Input settings by right clicking on DYN in the status bar and selecting the Settings option or by typing Dsettings at the command prompt. The figure above shows the Dynamic Input settings that allow you to modify the format and appearance of the Dynamic tooltips. These will give you the options to fine tune the Dynamic Input options to exactly what you want it to look like and how you want it to function, including the color and Transparency of the tool tips. I suggest taking some time to investigate the different settings, you might be pleasantly surprised.

Reading your Manager's mind

What CAD managers, or supervisors, would like to see out of a novice CAD user is likely not what you would always expect. A while back I posted a thread in the AUGI CAD managers forum to see what they thought I should focus on for a class I was writing. I was surprised to see how many of them were saying the same things I was already planning on saying. Here is a list of good general drafting practices that I've compiled after discussions with other CAD managers.

• None of the CAD Managers said I want someone who’s fast. It’s easy to want more speed so you can prove yourself at the new job. Experienced drafters and CAD Managers often see someone who is clicking their mouse like they’re playing a video game as someone who has potential to make mistakes. You don’t want them to have that impression of you.
• Always remember doing it fast twice is still slower that doing it carefully once. Don’t just work fast, work smart and find the right tool (command) for the job.
• If you find yourself saying “there must be a better way to do this” then you’re probably right. There is almost always more than one way to do something in AutoCAD. There may be a faster way that is worth investing a minute or two to discover.
• If you’re not sure about something, don't be afraid to ask a question. But only ask it once. Write down the answer so you can look it up later. There is such a thing as a stupid question; it’s the one you don’t ask, or the one you ask several times.
• Always check your plots before turning it in to the Engineer or Architect who gave it to you. Sometimes a mistake is obvious on paper that isn’t obvious on the screen.
• Always spell check a drawing before plotting it. Even someone with exceptional spelling skills can transpose letters when typing.

Welcome to my AutoCAD blog

Welcome to my AutoCAD power user Blog. This Blog is dedcated to showing AutoCAD users Tips Tricks and best practices to teach novice users the keys to being a power user.