autodesk constraints

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12/1/2005 - 10:00 am - 11:30 am Room:Swan 1 (Swan)

Moving Right Along: The Autodesk Inventor® Motion Constraints

Are you having trouble explaining to others how your new mechanism works? For that matter, are you fairly sure it is even going to work? Autodesk Inventor motion constraints can be a big help. In this course, you will learn how to apply assembly constraints that will allow you to replicate the motion of gears, pulleys, irregular cams, and rack-and-pinion mechanisms. This will include such topics as analyzing mechanism motion during the design phase to ensure proper operation, to check for interference within moving mechanisms, and to drive adaptive components. We will cover several tips, tricks, and techniques that can take motion constraints far beyond the usual textbook coverage. You will also learn how to capture assembly motions to an .AVI file so anyone can view them with the generic Windows Media Player.

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About the Speaker:

Bill Fane - BCIT / CADALYST

An AutoCAD software user since 1986, Bill was a product engineer and manager for Weiser Lock in Vancouver, Canada for 27 years. Bill has taught AutoCAD and mechanical design at the British Columbia Institute of Technology since 1996 and teaches Autodesk Inventor at the Institute’s Training Center. He has lectured on a wide range of subjects at Autodesk University since 1995. An active member of the Vancouver AutoCAD Users Society, he has written "The Learning Curve" column for CADalyst magazine since 1986, and writes about Autodesk Mechanical Desktop and Autodesk Inventor for Autodesk's Point A Toplines. He also writes for Inside AutoCAD Journal and Design Product News.

Moving Right Along: the Inventor motion constraints

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NOTE

This course is intended for intermediate users. I assume you have a working knowledge of the basic assembly constraints in Autodesk Inventor TM, so now we will go on to see some of the more advanced playing that can be done

with them. In particular, we will discuss the motion constraints and how to add movement to your models.

The example files will all open in at least release 9 or later, but the basic principles work in many earlier releases.

Wanna Drag? One of the many features that I find intriguing in Inventor is its dynamic assembly constraint analyzer. This means that it is not necessary for Inventor to have an “update” function when dealing with changes to an assembly. Changes are analyzed continuously, and any necessary updating takes place in real time. You can use your mouse to grab onto a partially-constrained component and drag it to a new location. As you do so, any other components that are constrained to it will follow along.

For example, consider the basic cylinder and crank assembly /IM-01-Piston & Cylinder/IM-01-Cylinder.iam. Simply move your mouse until the cursor arrow is located within the circular end of the crank pin.

Now press and hold the left mouse button down. While still pressing the mouse button, move the cursor in a circular motion. Keep it approximately within the circular crank pin end, and move it around the main bearing portion of the crankshaft. Observe how the connecting rod and the piston obediently follow along with proper rotary-to-oscillating and oscillating motions respectively.

For this to work, the assembly must be slightly under-constrained. Specifically, the piston cannot have a mate, flush, or insert constraint that prevents up-and-down motion, and the crankshaft cannot have an angle or other constraint that prevents rotation.

On the other hand, such lack of constraints can cause problems when creating 2D drawing views of the assembly. The solution is to apply the desired constraints, then suppress them when you want to study the mechanism’s motions. Just remember to unsuppress them before plotting the 2D drawing views.

You have now seen and used the basic dynamic constraint analyzer. So what can be done with it? It turns out that there are two major uses. Obviously, you can operate a mechanism in order to test that works properly.

Not so obviously, you can test if a model is properly constrained. For example, in an engine the crankshaft, connecting rods, and pistons should all move properly. On the other hand, you probably do not want the cylinder head to be able to move relative to the block. If you can move the head then it needs more restraints.

Let’s go back and look at the first use in more detail.

First, an observation. Notice how the piston pulls completely clear of the frame as it approaches the bottom of the stroke, but re-enters the bore properly on the way back up. A mate constraint was applied between the centerlines of the piston and the bore. They will remain aligned, regardless of whether or not the cylindrical portions remain engaged. Obviously the real world does not work this way. We can deduce a fundamental rule from this:


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NOTE Just because a modeled mechanism works properly does not

necessarily mean that the real mechanism will work too!

Let’s Go For A Drive… Having said that, a modeled mechanism can still be a very valuable tool both for analysis and demonstration purposes. Let’s start with demonstration mode.

Once you have designed a mechanism there is often a need to explain it to others. Since a word is worth .001 of a picture, an animated demonstration is usually better than a verbal description.

In the browser, you can expand the part entries to show their constraints. For example, I have expanded the entries for the frame and the crank. Clicking on a constraint will highlight the related items in the graphic window. The illustrations show the result of clicking on the Angle (325.00 deg) entry under the Crank. This constraint is grayed out in the browser to indicate that it is currently suppressed. If it were not grayed out then you would not have been able to rotate the crankshaft with your mouse. This “highlighting” step is not essential to the process, but it serves to highlight the constraint that will be driven.

Now we’ll right-click on Angle (325.00 deg) constraint under the Crank in the browser. When the context menu pops up, click on Drive Constraint. When the Drive Constraint dialogue box appears, we

click on the double chevron button in the lower right corner to display the full dialogue box.


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The illustration shows how I have filled in the Drive Constraint dialogue box. Starting in the upper left:

Start = 0.00 deg

End = 348.00 deg

Pause Delay = 0.000 s

“Drive Adaptivity” and “Collision Detection” turned off (no dot)

Increment: “Amount of value” button should be On, and value = 12.00 deg

Repetitions: Start/End should be On, and value = 5.0

Ignore the AVI Rate window for now.

Click on the double chevron button again to contract the dialog box.

Now click on the Forward button and watch in amazement as the mechanism automatically runs until the crankshaft completes 5 revolutions. Unfortunately, the speed at which it runs can depend on the speed of your CPU and graphics card. The ultimate speed limit is set by the size and complexity of your assembly.

If you want to slow it down, add a small number, for example 0.1, in the Pause Delay window or enter a smaller number in the Increment window in the expanded dialog. To speed it up, set a larger increment. Watch out for the “wagon wheel” effect when driving spoked wheels!

Click on the Reverse button and the mechanism will run backwards for 5 revolutions.

The remaining buttons perform the indicated actions, much like a VCR.

Pause the current operation. Drive or Reverse will resume it.

Reset to the start position.

Single-step in reverse

Single step forward

Advance to the end position

Closes the Drive Constraint dialogue box and re-sets the constraint to have the current value.

Closes the Drive Constraint dialogue box and returns the constraint to the value it had before you started driving it.


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Hints: • You can rename any constraint in the browser to make its relationship more obvious. For

example, the meaning of a constraint called “Drive Me” is pretty obvious.

• They can be driven even if they are not suppressed.

• They work with linear (mate, flush) constraints as well as rotary (angular).

• For the smoothest operation of a rotary motion, the End angle should be 360 degrees minus one increment (in our example, 360-12=348).

• Do not use an image or gradient background, or performance will plummet.

• Animating a mechanism like this is obviously an easy way of demonstrating it to other people.

Now let’s move on to the analysis functions.

Captain, Sensors Indicate A Collision… This time, we’ll drive the angle constraint with one minor difference. When we expand the dialog box, we’ll click on the Collision Detection radio button to turn it on.

Now when we click on the Forward button we can watch in amazement as the mechanism only completes part of a revolution. It will suddenly grind to a sickening halt and the Collision Detected alert box pops up. The offending parts are highlighted in red, indicating that the piston skirt is striking the crankshaft. The connecting rod is too short.

Hint: Collision detection only works at the increment of each motion step. If there is only a slight interference, and the step increment is large, your mechanism might “jump over” the collision.

We Must Adapt To Survive… Now we see how Adaptivity works in conjunction with driven constraints. In the browser we’ll right-click on the Con_Rod. When the context menu pops up, we’ll click on Adaptive to turn it on.

Next, we unsupress the grayed-out Tangent (0.010) constraint under the Crank, right below the Angle (325 deg) constraint. The piston will move until its skirt edge is 0.010 units above being tangent to the crankshaft, and the connecting rod will change length as required.

Now, we’ll drive our favorite Angle constraint on the crank, but before we actually run it we’ll turn

Collision Detection off and Adaptivity on. Now when we click on the Forward button the crankshaft completes 5 revolutions. This time, the piston does not reciprocate. Instead, the connecting rod lengthens and shortens to adapt to the changing geometry.

We can single-step the constraint until the connecting rod reaches its maximum length, when the constraint angle equals 180 degrees. At this point we click on Apply to accept the current values and to dismiss the Drive Constraint dialogue box.

Finally, we suppress the Tangent constraint under the crank, and turn Adaptivity off for the connecting rod. The connecting rod freezes at its new length.

Now when we drive the crank angle constraint again, with Drive Adaptivity turned off and Collision Detection turned on, we don’t get any collisions.


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Hints: • Collision Detection and Adaptivity only work when you are driving a constraint, and not

when you drag parts around manually.

• Driving Adaptivity is a cool way of demonstrating things like rubber diaphragms that stretch and shrink as a mechanism runs: /IM-02-Diaphragm/Assembly-diaphragm.iam.

Now we are ready to do the final showing of our mechanism. The problem is, the people who need to see it do not have Inventor and wouldn’t know how to use it if they did. No problem.

You Send Me… Inventor includes a provision for recording an AVI animation file while a constraint is being driven. This file can be played back using the Media Player program that comes standard with Windows, so everyone has it. The study of AVI files could be the subject of a full tutorial in its own right, so this time we will just hit the high spots to get you started.

All we need to do to create an AVI file is to click on the red Record button in the Drive Constraint dialogue box before we start the animation running. Supply a suitable file name when the standard file dialogue box pops up, and then click on Open. The file dialogue box will close. If a Video Compression dialogue box pops up, click on OK to accept the defaults.

Now click on the Forward button . The animation will run somewhat slower, because it is producing and compressing a frame-by-frame video as it goes.

Hints: • You may want to shrink the Inventor graphics window down to a smaller size before

recording to avoid producing MONSTER file sizes. The file size goes up as the square of the window size.

• If you slowly pan, zoom, or orbit as the operation is proceeding, then those actions will be recorded.

• Do not switch to another application while the video is recording. If you do, that excursion will be included in the video!

As indicated earlier, we can e-mail the resulting AVI file to people who do not have Inventor. They can play the AVI file back and can therefore be witness to the true genius of our design.

Get A Move On! Now let’s explore the motion constraints in Inventor.

Wait a minute. Don’t all assembly constraints serve to prevent relative motion between parts in an assembly?

Yes, most of them do. Inventor, however, has two constraints that serve to only partially limit motion. A better description would be to say that they control motion rather than constraining against it. They are intended specifically for use in studying mechanism motions. There are two variants of the Motion constraint, plus the one Transitional constraint.

Disk Looks Like An Interesting Assembly… Consider the simplified assembly IM-03-Disks.iam. The two disks are Insert constrained to circular features on a base plate. To avoid cluttering the view, the base plate is small enough that it is hidden behind the disks. The disks are free to rotate, so that we


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can drag either of them in a circular motion. For the time being, we’ll ignore the bar below the disks.

We’ll now place a constraint between the disks. We’ll click on the Motions tab, then click on the

right-hand Solution button. The dialogue box should now look like this:

Next, we’ll click on the outer rim of the larger circle, and then click on the outer rim of the smaller one.

The Ratio window will automatically change to 2.0, because in our example the larger disk has a diameter of 2 units and the smaller one has a diameter of one unit. Inventor has automatically calculated the ratio between them. We’ll click on Apply and then on Cancel.

Now we’ll drag the larger disk around in a circular motion. Observe how the smaller disk obediently follows, turning two revolutions for each single revolution of the larger disk. This motion also works in reverse; we can drag the smaller disk and the larger one will move appropriately.

Giving It The Gears… The two “Solution” options for the Rotation constraint suggest it can be used for same-way (belt or chain) mechanisms, or opposite-way (gear) mechanisms. Actually, it doesn’t really matter if you are running belts or gears, what really matters is the relationship of the direction vectors that appear when you select the linked details.

If both direction vectors face the same way then the resultant motion will match the “Solution” button. If things turn the wrong way in your assembly, simply edit the constraint and either change its solution type or the direction vector of one detail.

In the previous sample, we used plain “friction drive” disks. How about actual gears? Okay, here is a fairly long list of hints that apply to the Rotation constraint.

Hints: • You can select either a cylindrical surface or a circular face for the constraint. In fact, you

can mix & match within a single constraint. Inventor will automatically calculate the ratio based on the diameters.

• Gears do not normally have a cylindrical/circular detail at the pitch diameter. No problem; just pick any two details such as the bores, hubs, and/or faces, and then manually enter the gear ratio. This can be entered directly as a fraction; for example, in IM-04-gears.iam you would enter the ratio between a 39-tooth gear and a 20-tooth gear simply as 39/20 or 20/39, depending on which gear you picked first. Inventor will do the calculation.

• Gear teeth do not automatically mesh properly. They must be in the correct position before you apply the Rotation constraint. Good practice is to apply one or more “timing” constraints that set the correct mesh, such as the angle between bore keyways and the machine frame, or a tangent constraint between two gear teeth. If the gearset gets out of step, simply suppress the Rotation constraint, unsuppress the timing constraints, then suppress the timing constraints again, and finally unsuppress the Rotation constraint.


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• The constrained parts don’t need to actually touch each other. They can be displaced both radially and axially from each other.

• Gear axes need not be parallel. Bevel gears work quite nicely; IM-05-Bevel gears r9.iam.

Motion constraints cannot be “driven” directly, but they will function correctly if one of their linked parts is driven.

Like any constraint, the motion constraint can be edited. Simply right-click on it in the browser, then select Edit from the context menu. We can change the ratio, the solution, and even re-select the rotating elements.

Rack ‘Em Up… Now let’s investigate the “rack-and-pinion” option of the Motion constraint. In the Place Constraint

dialogue box, we click on the Motion tab then click on the right-hand Type button . This is the Translation-Rotation function. Going back to our earlier “two disks” example, we’ll move the cursor onto the rim of the larger disk and observe how the red arrow points “into” the disk as shown. We click on the disk to select it.

NOTE: With this constraint, we must pick the rotating element first.

Next, we’ll select the upper rear edge of the bar, as shown.

NOTE: We picked the edge of the bar, not a face. We’ll come back to this later.

Having selected the edge of the bar, the Distance window will be highlighted. This shows the distance that the linear object will translate for each revolution of the circular object. By a strange coincidence, it always seems to be some multiple of 3.14159268…

We’ll click on Apply, and then Cancel. Now we’ll use the cursor to rotate either disk, and to slide the bar back and forth. Observe how all three objects are connected by and driven by their motion constraints.

The Wheel Deal… Now let’s have a bit of fun with another assembly file IM-06-Steering.iam. This will show you some of the things that can be done with motion constraints. We’ll use the cursor to rotate the hand wheel. Watch in amazement as the entire mechanism works from the hand wheel, through the universal joints, and to the rack and pinion. Conversely, we can drag the rack back and forth and the hand wheel and the u-joints will follow.

We can drive the angle constraint between the handwheel and its bearing, and the mechanism will automatically go through six cycles, being out and back three times.

Now that we have seen the basic motions, here are a few tips and pointers that apply to the Translation-Rotation constraint.


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Hints:

• As we saw when constraining the gears, Inventor does not automatically apply the correct ratio to a rack and pinion unless the pinion includes a circular feature at the pitch diameter. We had to enter the ratio manually when constraining the assembly, based on the pitch diameter of the pinion.

• Again, Inventor does not automatically mesh the rack and pinion teeth. We had to have things correctly positioned before applying the constraint. Again, we should provide suppressed “reset” constraints if things get out of step.

Note that I have been calling this the “Translation-Rotation” constraint, rather than the “Rack and Pinion” constraint. Constrained objects do not have to touch each other. In this assembly, we applied the Rotation/Translation constraint between the hand wheel and the rack as well as between the pinion and the rack. The pinion then drives the constraints back up through the universal joints. I found that this gave better performance, especially when driving the hand wheel manually on a slower computer. I first tried constraining it the “logical” way, down from the hand wheel and through the u-joints. I then applied the Rotation/Translation constraint between the rack and the pinion, but I found that if I moved the hand wheel or the rack very quickly I could confuse Inventor and things would get out of step.

I emphasized earlier that we had selected the edge of the bar. This is not strictly a fixed requirement in its own right. You can select an edge or a face of the “rack” providing it is free to move in the “vector direction” that was shown when it was selected. In our examples, we could have selected a long edge or an end face of the rack, but not the top/bottom or front/back faces, nor can we select any of the “short” edges.

Once again, the direction vectors determine which of the two possible “solution” cases apply.

Assembly IM-07-Steering.iam shows that the axis of rotation does not need to be at right angles to the translation direction. This constraint simply says that there is a relationship between the rotation of one detail and the translation of another. This variant of the steering assembly works just as well.

The People On The Bus... Time to move on (pun intended) to explore the Transitional motion constraint. The Transitional tab of the Place Constraint dialogue box is simpler than the Motion tab, but it unleashes a very powerful constraint. This constraint can best be described as a “cam and follower” motion constraint. It can be used to model and simulate a range of motions far beyond that which can be accomplished with the regular assembly constraints and the two Motion constraints. A quick demonstration using IM-08-transition1.iam (see next page) will show you the some of the power of this constraint.

To apply this constraint, we must click on the curved face at the bottom of the vertical follower first, and then click on the upper curved face of the cam. We cannot click on an edge or vertex.

For best results, the cam and follower should be in approximately the correct mating position, and the selected face of the cam should be the first face the follower will touch when the constraint is applied.

We can now drag the cam around or drive it and the follower will faithfully follow it.


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This constraint is called the Transitional constraint because it is not limited to simple circular cam shapes, such as could be handled by a simple Tangent constraint. It can follow the “transitions” between arc, line, and spline curves.

But Wait, There’s More! The transitions do not even have to be smooth tangencies. IM-09-transition2.iam shows a sharp-cornered cam. All we have to remember is that we must select the contact face of the cam first, and then select the cam face

Once again, we can drag the cam around or drive it and the follower will faithfully follow it.

We are not limited to having the follower slide linearly, as we have used in our examples. A rocker arrangement, as seen in the valves of a car engine, will also work.

The Transitional constraint will also work if we have used a spline to define the cam, as in IM-10-transition3.iam. It can be a little finicky, however, and it will often suddenly snap over to picking some other face for the cam surface if we are dragging in too quickly, especially if the cam has a circular bore through it.

Mathematically, a hypercycloid is the “perfect” shape for a cam profile but Inventor prior to the Design Accelerator Release 10 does not have such a curve. One could be approximated in earlier releases using a spline curve.

It’s A Flat World… So far, we have been using a curved follower. IM-11-transition4.iam will show that a flat-faced follower works every bit as well, with one condition.

The one condition is that the flat face of the follower should be wide enough that it spans the contact face of the cam. If the follower in this example or the previous one were installed the other way up, so that the smaller flat face contacts the cam, then it will tend to “dig in” and stick, just as it would in the real world.


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It’s A Really Flat World… If you are impressed by what we have done so far, look at IM-12-transition plate.iam.

Right! A Transitional constraint also works between a follower and a flat or plate cam. The Transitional constraint will also work within a closed slot cam profile. A plate cam does not have to be open-sided as shown in the example.

All we need to remember is to select the contact face of the follower first, and then pick any face on the mating edge of the cam.

Now that we understand the basic principles, here are a few tips, tricks, and pointers.

Hints: • As we have seen, the follower face must be selected first and must be a single flat or arc

face.

• The cam face can be any combination of lines and arcs. Sharp corners will work, but as in the real world you will find that things work more smoothly if there are small radii on the corners. For example, the “sharp-cornered” cam example I used actually has very tiny radii on the corners.

• Again mimicking the real world, a flat-faced follower should be a little wider than the longest contact face on the cam. We don’t want sharp corners that could dig in.

• Unlike all other normal and motion constraints, Transitional is not “infinite”. The follower face must always touch the cam face. There is no offset value to space the contact faces radially apart as in other constraints, and they must also touch in the axial direction.

Hit Me! I was going to present a complete class on the contact solver because it is so powerful and versatile, but then I realized it can be covered in three sentences. IM-13-contact.iam is an example.

1. Right-click on any part in the browser, or in the graphics window, then click on Contact Set. Repeat for any number of parts.

2. Click on Tools | Activate Contact Solver.

3. Move any part in the contact set. When it hits any other part in the set then the second part will move if it is able to; if not, the first part will stop moving.

That’s it! There is only one contact set. If anything in the set hits anything else in the set then the contact solver works.

Hints: 1. You can mix and match linear and rotary motions in the same assembly.

2. The solver only “pushes”; the hitter will not pull the hittee (?) back.

3. The contact solver works when parts are manually dragged or are moved by a driven constraint, with one minor hiccup: if the hittee cannot move then it will stop the hitter and hence act as a travel limiter when parts are dragged manually, but will give bizarre results when propelled by a driven constraint.


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And The Bad News Is… Unfortunately, there are three common types of motions that Inventor cannot produce.

1. Don’t Interrupt! Inventor can’t produce an interrupted, non-continuous cam motion. If you try to use the contact solver then the peg will push the follower up on the first revolution but will not pull it back down.

To make this work, all we need is an invisible cam with a transitional constraint. Note that if we also turn off Enabled, then the part does not contribute to mass calculations but its constraints are still active. I once built an assembly model of an electric fuel pump that demonstrates its function. The spring and diaphragm flex, the contacts operate, and the valves open and close. It is all driven by an invisible series of cams on a single shaft, much like the “line shaft” that was used to power old factories.

2. Go figure… Here is another example of a motion that is “impossible” to create using Inventor. The trick to this one does not even use any fancy motion constraints. All we need to know is that Inventor will allow us to use a relational formula any time it needs a value. This includes the offset and/or angular values of a constraint. Okay, there is one other thing we need to know. Each constraint “offset” has a parameter name, just like the dimension parameters in a part sketch.

The “timing belt” in this assembly actually consists of four separate parts; the two vertical straight sections, and the two arc sections. The four sections are mated with a simple line-to-line constraint at each end. They act as “hinges”. In addition, the centre lines of the two arc sections are mated line-to-line with the centre lines of the sprockets.

A simple angle constraint then ties the rotational alignment of the bottom arc to the machine frame.

Now comes the cunning bit. The value for this angle is actually a formula that links it to the angle constraint that drives the rotation of the sprocket, like this:

d61%15deg

In this formula, d61 is the name of the angle parameter between the keyway in the lower sprocket and the frame of the machine in my particular assembly. The sprocket has 24 teeth, so each tooth encompasses 15 degrees.

In Inventor formulas, the % sign indicates the “modulo” or “remainder” function.

The result is that as the lower sprocket is driven through a full revolution, the formula takes the current value of d61, divides it by 15, and returns the remainder. The resultant is then fed to the angle constraint that orients the lower belt arc segment.

For example, as the sprocket travels through 0-15 degrees of travel the resultant of dividing it by 15 returns a matching number (1/15=0, plus 1 remainder. 2/15=0, plus 2 remainder, etc).


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However, when the angle d61 hits 15, then 15/15=1 plus 0 remainder and so the arc, and hence the other three segments, snap back to 0.

As the angle d61 increases from 16-29, the remainder cycles through 1-15 again, and so on. The belt appears to move continuously. To help understand this, turn off visibility of a straight section and increase the pause delay to slow down the action.

This, of course, is the exact same principle as movies or TV. It isn’t really an optical illusion, it just looks like one. I love lying to computers…

3. Spring Has Sprung… I often get e-mails asking how to produce an associative spring that will automatically change length as a mechanism operates. Unfortunately, part parameters are not directly available within an assembly. I suppose you could do it with a pile of VBA programming…

…or you could cheat. To build this spring I first created a part that is a simple half-coil; I revolved a circle 180° about an axis.

I then created an assembly and inserted enough half-coils. Now it was time to constrain it:

• Each end of each half-coil has an Insert constrain to the next half-coil.

• The first coil has a Mate or Angle constraint to prevent it from rotating about its central axis. It is also Tangent to the base plate. Note that it must be able to shift sideways a little bit.

• The centre point of all remaining half-coils except the last one is Coincident with a suitable central axis.

• The last segment is tangent to the upper plate, which in turn is constrained so it stays parallel with the base plate.

• Applying the Contact Solver between two segments will prevent things from flipping inside-out if you attempt to overtravel the spring.

The one serious limitation is that all segments and the upper and lower plates must all exist in the final assembly. You can build a spring sub-assembly and then add it to a main assembly, but it won’t work until you promote all of its components up to the assembly level in one operation.


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Which Way You Goin’? Inventor has two other methods for producing animations. Each of the three methods has its advantages and disadvantages:

1. Motion constraints:

a. For:

i. Relatively simple (your assembly needs constraining anyway).

ii. Can do interference checking, can drive adaptivity, can use contact solver.

b. Against:

i. Can only drag or drive one constraint at a time.

ii. Cannot control part visibility.

2. Presentations:

a. For:

i. Multiple motions at one time; e.g. exploded views.

ii. Part visibility can be turned on and off during an animation.

iii. “camera” can move automatically during animations.

b. Against:

i. Cannot do analyses.

3. Studio (new to R10)

a. For:

i. Photorealistic renderings.

ii. Complex, powerful animation controllers.

b. Against:

i. Long, high-resolution animations can require “geologic” time frames to render, and can produce “government spending” file sizes.

And In Conclusion… Driven and motion constraints in Inventor can be a powerful analysis and visualization tool. Don’t be afraid to experiment and explore; this session has just scratched the surface.

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