iSpy Autodesk Inventor® iFeatures 404_MA31-5[1]

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11/30/2006 - 8:00 am - 9:30 am Room:Marcello - 4501 (MSD Campus

iSpy Autodesk Inventor iFeatures

Are you using the same type of feature over and over again in many different parts? Do you find it anuisance to have to sketch-constrain-dimension-solidify them over and over again? Do you wish youcould use standard "placed features" similar to the standard holes, fillets, and chamfers? Well, nowyou can create your own catalog of your own standard iFeatures and insert them into any part modelas easily as dragging and dropping from Windows Explorer. There's more! iFeatures can also be"table-driven" so that the user can select a particular feature size or configuration as they insert it,much like placing a standard hole feature.@x@In this presentation, we will show you what iFeaturesare and how to create and use them.

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About the Speaker:

Bill Fane - British Columbia Institute of Technology

An AutoCAD software user since 1986, Bill was a product engineer and manager for Weiser Lock inVancouver, Canada for 27 years. Bill has taught AutoCAD and mechanical design at the BritishColumbia Institute of Technology since 1996 and teaches Autodesk Inventor at the Institute's TrainingCenter. 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 forCADalyst magazine since 1986, and writes about Autodesk Mechanical Desktop and AutodeskInventor for Autodesk's Point A Toplines. He also writes for Inside AutoCAD Journal and DesignProduct News, and Cutting Tool Engineering.

[email protected]

Stay Connect to AU all year at www.autodesk.com/AUOnline


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NOTE:

This course is intended for intermediate Autodesk Inventor users and

above. I assume you have a good working knowledge of sketching,

constraining, dimensioning, solidifying, and combining features. Youshould also be familiar with work features, placed features, and

projected geometry. The material to be covered applies to all

releases of Inventor (the oldest I have that is still installed is 6.0)

Play It Again, Sam

Actually, Humphrey Bogart never said that in the film Casablanca. What he really said was Justkeep playing, but the misquote works better for our purposes.

As the course description says, Are you using the same type of feature over and over again in

many different parts? Do you find it a nuisance to have to sketch-constrain-dimension-solidify themover and over again? Do you wish you could use standard "placed features" similar to the standard

holes, fillets, and chamfers?

Well, you can, and it is remarkably easy to do. In fact, it is so easy that Im going to have trouble

padding this presentation out to 1 hours.

Lets start with a quick demonstration of how to insert an iFeature. Well come back later to exploreit in more detail.

1. First, open or create a suitable part to which you want to add an iFeature.2. Next, click on the Insert iFeature tool , which launches the Insert iFeature

wizard.

This is a simple 4-step wizard (Figure 1):

Figure 1: TheInsert iFeature wizard

a. Browse to an existing iFeature file.b. Locate its approximate position:

i. Select a suitable insertion plane.ii. Drag it to an approximate position, and rotate if desired.

c. Specify dimension values for the size of the new feature, as appropriate.d. Specify its exact location, or accept the default.


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Thats it!

Okay, if that was too complicated, here is a simpler process:

1. Use Windows Explorer to browse to a suitable file.2. Drag and drop the file from its folder into your part.3. the Insert iFeature wizard comes up running as per step 2 above. You can now complete the

remaining three steps.

In The Beginning

Now lets walk through the quick creation of a simple iFeature. Once again, we will come back later

to analyze the details.

Lets assume you often need to place pentagon-shaped holes through plates.

1. Start a new part.2. Draw a Rectangle. It does not need to be dimensioned or constrained, as long as it is large

enough to accommodate your pentagon.

3. Extrude it to any arbitrary thickness.4. Start a new sketch on top of your extruded slab.5. Use the Project Geometrytool to project the origin center point into the current sketch.6. Create a 5-sided Polygon whose center is coincident with the projected origin center point.7. Constrain one side to be horizontal.8. Draw a construction circle whose center is coincident with the projected origin center point

and is tangent to one side of the pentagon.

9. Dimension the circle (Figure 2).

Figure 2: the dimensioned pentagon

10.Return, and cut extrude the pentagon through All the slab.11.Use the Parameters tool to rename the circle diameter to Pentagon_Dia.So far, all we have used are normal Inventor sketch and extrude functions. Now comes thestuff that is unique to iFeatures.


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12.Select Tools | Extract iFeature.13.Click on the pentagon feature in the browser tree or in the model itself. The Create iFeature

dialog box will now look like Figure 3.

Figure 3: the Create iFeature dialog box.

14.Click on Save, and then give it a suitable file name and location. By default, it will offer thelocation specified by Inventors application options.

Congratulations! You have just created your first iFeature! The actual extraction process reallyonly took 3 steps, because the rest of it was involved with creating the feature itself.

Put it there!

Lets do a quick test insertion of our new iFeature, then go back to look at some of the fineprint. It can be inserted back into the part from which it was extracted, or into any existing

part.

For our purposes, lets start a new part, and once again well just create a simple rectangularbrick.

Having done that, we will now insert our new iFeature using the Insert iFeature tool. This time

we will take a bit closer look at each step.

1. Select: Select our Pentagon iFeature file. Nothing too obtuse here.2. Position:

a. The wizard prompts us to Pick profile plane. As usual with plane selection inInventor, it will offer the first plane that the mouse touches. You can move to other

planes, and you hover over a plane to get the usual select-other-plane tool. Click on

a suitable plane.

b. There is no prompt at this point, other than the fact that the crossed arrows/curvedarrow icon changes color. In fact, it is asking you to select an approximate position.

i. You can click and drag the crossed-arrows portion of the icon to move theiFeature

ii. You can click on the curved arrow portion to rotate it. You can also enter anexact value into the wizard.

3. Size: The wizard now displays the one key value parameter we selected during extraction.This is the size of the inscribed circle around which our pentagon was drawn. We can enter

any desired value into the wizard. Note that we cannot change the taper angle, because wedid not include it in our original selection.


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4. Precise Position: This title is slightly misleading, in that we dont actually move the iFeatureto a precise position. There are two choices, so in a blinding flash of logic we will explore the

second option first because it is the default. Two choices are:

a. Do not activate sketch edit immediately(the default): This simply completes theinsertion of the iFeature at its current location. Note that it drills all the way through

the recipient part, because the original source feature was created that way.

b. Activate sketch edit immediately: In this mode, Inventor exposes the underlyingsketch profile for the feature. We can then apply dimensions and constraints toposition it precisely, as if it were a normal feature sketch. In this case we need toclick on the usual Return button to complete the insertion process.

It doesnt really matter which positioning mode we choose, because as you have probably realizedby now the entire iFeature mechanism is simply a quick and easy way of creating a sketch,

dimensioning and constraining it, and then solidifying it. We can come back at any time to edit the

sketch, within certain limitations to be covered later.

Extraction: The Fine Print

Now that we have seen the basics, lets look at the specific details of the extraction/definitionprocess.

1. Unlike AutoCAD block definitions and insertions, there is no insertion point specification.We use normal Inventor dimensions and constraints to define the location.

2. Watch out for dependencies. You may have noticed that when we defined our pentagon wedid not dimension or constrain it to the existing slab extrusion but left it floating. If we had,

then those lines, circles, points, etc would have carried over into our extracted iFeature.

This works, but it can get a little messy because now those secondary items need to belocated relative to the recipient part, instead of just locating our primary pentagon feature.

In Figure 5, we would need to apply Co-linearconstraints between the two reference linesand two edges of the part. This technique can be valid in certain circumstances, but is

usually too limiting.

Figure4: An over-located

sketch...Figure 5: ...can cause

problems when inserting theiFeature


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3. Any formulas or relationships are maintained within the sketch, or within parameters fromother sketches.

4. You may have noticed that our first example involved a Join (add), whereas the pentagoninvolved a Cut (subtract). In the latter case, the iFeature we have defined is a Seinfeldfeature; it is nothing, it is just the hole. We can also define an Intersect iFeature.

5. We can use all of the termination methods:a. Distanceb. To nextc. Tod. From-Toe. All

6. and modes. We can flip the direction, or specify the mid-plane mode.7. If we rename parameters then they automatically transfer to the key value column when

the iFeature is extracted.

a. Key values are the only ones that can be specified during insertion or edited later. Allother sizes are fixed.

b. Key values can be added to or removed from the list. This includes generic d0, d1items that we did not rename.

c. Unwanted renamed parameters can be removed from the key value list.8. Prompts can be re-worded during the extraction process.9. We can select multiple features, with different termination methods and join/cut/intersect

modes. For example, our pentagon hole could have a specific depth, plus a round hole inthe center that goes through All.

a. It is usually best to place a Coincident constraint between the projected center pointorigin and a logical detail in the first sketch. This becomes more significant when we

select multiple features in the part to define a single iFeature. The later sketches canbe defined relative to the center point, eliminating the need for references to othergeometry that we dont want in the iFeature.

b. When defining a new sketch plane, Inventor can be set so that any existing edgesthat lie on the new sketch plane automatically get projected onto the sketch plane as

reference edges. Be careful they dont get referenced, or they will get carried

forward into the iFeature.

10.The features need not be contiguous. We can thus create an iFeature that consists of aseries of holes in a pattern (see the D-Sub samples supplied with Inventor in the Punches

catalog).

11.Look at the Create iFeature dialog box again, and note the Limitcolumn in the SizeParameters region. Click on the current value for any parameter, then click on the down-arrow that appears to get a drop list of options:

a. None is the default, which means that at insertion time the user can insert anydesired value. Interestingly, it accepts negative values. This is reasonable for certain

cases such as the distance between two details, where it effectively produces amirrored version of the detail. The strange thing is that it also accepts negative

values for illogical situations like the diameter of a hole, in which case it simplyignores the negative sign.


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b. Range lets you specify upper and lower limits. For example, we might say that theinscribed circle of our pentagon must be at least 3.0 units but not more than 6.0

units. The user can provide any value within this range.

c. Listlets us create a list of pre-defined exact values from which the user must selectone at installation time.

Different parameters can have different limits, so that a structural shape could be limited to

certain stock cross-sectional sizes but its length could be anything the user wants providedit is longer than a minimum size and less than or equal to a full bar length.

Insertion: The Fine Print

There are really only three additional details to consider:

1. If your iFeature contains multiple sub-features, and/or if your definition feature requiresspecific termination planes, then they must be specified during insertion. You can click on

each of the work planes that appears, and then click on its target plane. All referencegeometry must be located, so now you see why we dont want extraneous items in the

iFeature definition. It may not be possible to locate some of them at logical locations.

2. If you have clicked on a plane in the graphic screen to select it before you invoke the InsertiFeature tool, then Inventor automatically assumes that you want the feature placed on the

selected plane. If you dont, then click on its name in the Insert iFeature wizard and it willbe released for normal placement.

3. Note the rotation angle during insertion. Once you have defined it, it appears to be frozenand cannot be changed. There is a work-around, however, that I will cover under Editing.

The More Things Change

the more it looks like a normal design project. There are two types of editing:

1. Editing of individual insertions:a. The sketch for each insertion can be edited like any other sketch, with a couple of

limitations:

i.

You can only add/edit dimensions and/or constraints that locate the sketch,but not components within the sketch.

ii. You cannot edit the insertions rotation angle by applying dimensions orconstraints to the sketch. There are two work-arounds:

1. Include an angle dimension between a component of the sketch andreference geometry from the rest of the part, or:

2. Use the Rotate 2d sketch tool and rotate the sketch relative to itssketch coordinate system.

b. An inserted feature can be edited:i. Right-click on it in the browser, then select Edit iFeature from the context

menu.ii. You can only edit those dimensions that were selected as key values when the

iFeature was extracted, and only within any limits or tables that may have

been set.

2. Editing of the iFeature definition file:a. You can adjust the values of any dimensions that were selected as key values. This

includes changing the limits from None to Range or List.

b. You can add or subtract entries from an existing List table.


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c. You cannotselect additional nor remove any existing key values. It would appearthat you can add new parameter columns to a table, and put specific values in them,

but they do not actually change the host part. For example, I set up a table within

my Pentagon iFeature to say that a 1 feature had zero taper whereas a 2 featurehad 10 taper. Upon inserting or editing the iFeature I found that selecting the 10

taper selected the 2 size, but the feature itself was not actually tapered.

d. You can create a new definition in a source file and then extract a new iFeaturedefinition that over-writes the existing file.

e. Any editing or redefining of the iFeature file is notretroactive and has no effect onany existing insertions anywhere in any existing or in-process drawing.

Tips & Tricks

1. Theory and practice are the same in theory, but not in practice. In theory, any existingfeature or features can be extracted from any existing part file in order to create an iFeature

definition file. In practice, this can often lead to complications with extraneous reference

geometry. The best practice is usually to build a specific source file, in which the futureiFeature is self-contained and is not dependent on other existing geometry. This means that

a CutiFeature will be under-constrained because it is missing the positional dimensionsand/or constraints. On the other hand, a Join feature usually can and should be constrained

to the coordinate system.

2. Now where did I put that filea. When extracting or inserting an iFeature, Inventor first offers or looks in the folder

specified in Tools | Application Options | iFeatures. There are two folder

specifications under this tab, because there are two ways of finding an iFeature:

i. iFeature Rootspecifies the main location. If you activate the View Catalogtool, then Inventor uses Windows Explorer to display the contents of thisfolder. As demonstrated earlier, you can then browse and dragndrop from

this folder to place an iFeature.

ii. iFeature User Rootspecifies the default folder offered by the Extract iFeatureand Insert iFeature tools.

By default, these two folders are the same and both point to the

C:\Program Files\Autodesk\Inventor nn\Catalog\

folder. On the other hand, either or both can point to network folders, so all users inan organization can have access to the same iFeature libraries.

If you change these folder locations, then when you extract or insert an iFeatureInventor may complain that its location is not in the current project search path. This

does no harm, but if you object to the repeated reminders then you can always add

them to the project search path.

And In Conclusion

Dont be intimidated. Inventor iFeatures are actually a quick, easy way of producing multipleinsertions of the same or similar features in one or many part models without having to

sketch/dimension/constrain/solidify each one each time. Start small, with simple single-featuresingle-value extractions and then just work your way on up.

And Dont Forget

www.autodesk.com/auconnect

will connect you to Autodesk University content files. This includes course handouts, sample files,

datasets, and the a/v files for over 100 presentations that were recorded live.


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iSpy Autodesk Inventor® iFeatures 404_MA31-5[1]