Skeleton Modeling

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ME 380Advanced Computer Aided Engineering

Chris MorganPrecision Systems Laboratory

University of Kentucky

Skeleton Modeling and SketchingStrategies

March 24, 2006


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Intent Manager

Once a designer has a complete understandingof the intent manager process, sketching

becomes an efficient processForcing Pro/E to make the correct assumptions

during the sketching process can be difficult, but understanding the terminology andsymbols will relieve some of this frustration


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Alignments and Dimensions

Alignment-Used for locating section

Dimensions-Used for location sizing of elements

Alignments always create external referencesand should therefore reference stable features

(a datum plane is usually stable, the edge of a part is very instable as it my change or bedeleted during the redesign process


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Guideline for References

1. All references create parent/child relationships Use as many references as required, but no more than required Know specifically what reference is selected (surface vs. edge,

feature, etc.) Use references that are robusti.e., they are not subject to drastic

change or elimination. Use references that belong to the same feature whenever possible

2. Any entity to be used for alignment (with a point, vertex,curve, etc.) should be selected as a reference.

3. Any entity to be used for a dimension should be selected for

a reference.4. Unless guides 1 through 3 above indicate otherwise, use thedefault references.

Quoted from Mechanical Engineering Design, Archibald


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Sketching Strategy

1. Select references carefully2. Exaggerate the sketch to obtain desired constraints and to

avoid section entities of greatly different sizes. (Modify

dimensions to obtain the correct geometry.)3. When modifying a sketch of the first feature in a new part,deselect the Regenerate

4. Select references, sketch, constraints, change dimensions,and modify dimensions in that order.

5. If several corners are to be filleted, sketch straight lines and use the Fillet option. Use the equal constraint icon toconstrain fillets to the same radius

6. Use Use Edge or Offset Edge options to copy or offset fromexisting geometry.

7. Use the Point on Entity icon to force alignments whenrequired.

Quoted from Mechanical Engineering Design, Archibald


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Sketching Strategy

Use constraints to reduce the number ofdimensions needed in a sketch

Vertical constrains a line to be verticalHorizontal constrains a line to be horizontalPerpendicular constrains 2 lines to be perpendicular Tangent constrains a line or curve to be tangent with

a curveMidpoint constrains a node to the midpoint of a lineCollinear constrains a line or point to be collinearwith another line or pointSymmetry constrains points to be symmetric about acenterlineEqual constrains a line length or radius to be equal

Parallel constrains 2 lines to be parallel


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Rename Features

Highlight and right click on the RIGHT datum plane(either in the model tree or on the screen)

Select Rename and name this planeCHAMBER_RIGHT Highlight and rename the rest of the datum planes tothe names listed below


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Create Stand offset Plane

Select the Datum Plane Tool icon at the right

Click on the CHAMBER_RIGHT plane and set the offset to an arbitrary value,select OK

Highlight and right click on the Plane you justcreated and select Edit

Double click on the offset dimension and

change the dimension to STAND_OFFSET, hit Enter When asked, Do you want to addSTAND_OFFSET as a feature relation, select

Yes . Click the regenerate icon Change the plane name to STAND_RIGHT

Make sure you pay attention to the command prompt at the bottom of thescreen, this will assist you when making selections of references


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Create CHAMBER_BOTTOM Plane


Click on the CHAMBER_TOP plane and set the offset to an NEGATIVE arbitraryvalue, select OK

Highlight and right click onthe Plane you just created andselect Edit

Double click on the offsetdimension and change thedimension toCHAMBER_HEIGHT

When asked, Do you wantto add CHAMBER_HEIGHTas a feature relation, selectYes .

Regenerate Change the plane name toCHAMBER_BOTTOM


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Create STAND_TOP Plane


Click on the CHAMBER_TOP plane and set the offset to an arbitrary value, selectOK (note: if the chamber_top plane is not highlighted, right click to query select

until it is. Highlight and right click onthe Plane you just created andselect Edit

Double click on the offsetdimension and change thedimension toSTAND_HEIGHT

When asked, Do you wantto add STAND_HEIGHT asa feature relation, select Yes .

Regenerate Change the plane name toSTAND_TOP


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Select the Datum Axis Tool icon

Hold down the CTRL button and select the CHAMBER_FRONT and POWER_RIGHT datum planes.

Create Power Centerline Axis

Select OK

Rename the feature to POWER_CENTERLINE


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Hold down the CTRL button and select the STAND_TOP andCHAMBER_FRONT datum planes.

Create Shaft Centerline Axis

Select OK

Rename the feature toSHAFT_CENTERLINE


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Sketch datum points

Select the sketch point button from the toolbar, when asked for the sketch plane select the CHAMBER_RIGHT plane and select the CHAMBER_TOP plane as the TOP reference.

Click sketch from the menu


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Sketch Datum Points (cont.)

Select the followingreferences-

CHAMBER_TOP

CHAMBER_FRONT STAND_TOP

Zoom in around theintersection of the reference

planes and place three datum points and dimension themas shown

Select to finish the pointsRename the points to

DISP_ROD _ PTS


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Add Relations for DISP_ROD_PTS

From the menu bar select Tool-RelationsType in the relations as shown belowThe relations for the plane offsetsshould already exist. You can addcomments by typing /* before thestatementTo find the correct dimension symbolsfor the disp_rod_pts (they might bedifferent from mine) click on the

DISP_ROD_PTS in the model tree.Click on the dimension in the graphicwindow and the symbol will appear inthe Relations window.Add a relation for the-

Conn_rod_lengthGapDisplacement/2

Click OKRegenerate


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Select the sketch point button from the toolbar,when asked for the sketch plane select the

POWER_RIGHT plane and select theCHAMBER_TOP plane as the TOP reference.

Click sketch from the menuSelect the following references-

CHAMBER_TOPCHAMBER_FRONT STAND_TOP

Place three datum points and dimension them asshown

Select to finish the pointsRename the points to POWER_ROD_PTS

Sketch datum points


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Select the sketch point button from the toolbar, when asked for the sketch plane select the CHAMBER_FRONT plane and select theCHAMBER_RIGHT plane as the RIGHT reference. Click sketch from themenu.

Select the following references-STAND_RIGHT STAND_TOP

POWER_RIGHT CHAMBER_RIGHT

Sketch datum points


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Add Relations for SHAFT_PTS

From the menu bar selectTool-RelationsType in the relations as

shown belowAdd a relation for the-

Bearing_mount_lengthConn_rod_dia/2+0.0625

Click OkRegenerate


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Create Chamber Surface

Click on the Revolve button on the toolbar Click the Revolve As Surface button at the bottomSelect Placement-Define at the bottom of the screen

Select the CHAMBER_FRONT datum plane for sketchingand the CHAMBER_RIGHT plane as the right reference,then click SketchAdd the following references:

CHAMBER_RIGHTCHAMBER_TOPCHAMBER_BOTTOM


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Create Chamber Surface (cont.)

Sketch the section shown belowSketch the centerline of revolution firstSketch the three lines and add the dimensions shown (note: the diameterdimension can be made by selecting the vertical line, then the centerline,

then the vertical line again and middle click to place the dimension)Set the horizontal lines to equal length by clicking the constraint button,selecting the equal icon, and selecting the two lines.Select , when finished

Rename feature CHAMBER_SURFACE


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Add Relations for Chamber surface

From the menu bar select Tool-RelationsAdd a relation for the-

Chamber_dia

Click OK


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Create Displacer Surface

Click on the Revolve button on the toolbar Click the Revolve As Surface button at the bottomSelect Placement-Define at the bottom of the screenSelect the CHAMBER_FRONT datum plane for sketching and theCHAMBER_RIGHT plane as the right reference, then click SketchAdd the following references:

CHAMBER_RIGHTDISP_ROD_PTS (bottom point)


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Create Displacer surface (cont.)

Sketch the section shown belowSketch the centerline of revolution firstSketch the line and add the dimensions shown (note: bothdimensions are diameter dimensions)Select , when finished Rename feature DISPLACER_SURFACE


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Add Relations for Displacer surface


Disp_diaDisp_rod_dia

Click OK


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Create Power Piston Surface

Click on the Revolve button on the toolbar Click the Revolve As Surface button at the bottomSelect Placement-Define at the bottom of the screenSelect the CHAMBER_FRONT datum plane for sketching and the

POWER_RIGHT plane as the right reference, then click SketchAdd the following references:POWER_RIGHTPOWER_ROD_PTS (bottom point)


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Create Power piston surface (cont.)

Sketch the section shown belowSketch the centerline of

revolution firstSketch the 2 lines and addthe dimensions shown(note: both dimensions arediameter dimensions)Select , when finished Rename feature

POWER_PISTON_SURF ACE


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Add Relations for Power Piston surface


Power_piston_diaDisp_rod_dia

Click OK


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Create Power Cylinder Surface

Click on the Revolve button on the toolbar Click the Revolve As Surface button at the bottomSelect Placement-Define at the bottom of the screenSelect the CHAMBER_FRONT datum plane for sketching and thePOWER_RIGHT plane as the right reference, then click SketchAdd the following references:

POWER_RIGHTCHAMBER_TOP


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Create Power Cylinder Surface (cont.)


revolution firstSketch the 2 lines and addthe dimensions shown

Select , when finished Rename feature POWER_CYLINDER_SU RFACE


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Add Relations for Power Cylinder Surface


Power_chamber_heightPower_piston_dia

Click OK


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Create Displacement Gland Surface


CHAMBER_RIGHTCHAMBER_TOP


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Create Displacement Gland Surface (cont.)



Select , when finished Rename feature DISP_GLAND_SURFACE


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Add Relations for Displacement Gland Surface


Disp_rod_dia

Click OK


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Create Displacement Crank Surface


STAND_TOPDISP_ROD_PTS (top point)SHAFT_PTS (left end point)


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Create Displacement Crank Surface (cont.)



Select , when finished Rename feature DISP_CRANK_SURFACE


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Create Power Crank Surface

Click on the Revolve button on the toolbar Click the Revolve As Surface button at the bottomSelect Placement-Define at the bottom of the screenSelect the CHAMBER_FRONT datum plane for sketching and thePOWER_RIGHT plane as the right reference, then click SketchAdd the following references:

STAND_TOPPOWER_ROD_PTS (top point)SHAFT_PTS (right end point)


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Create Power Crank Surface (cont.)



Select , when finished Rename feature POWER_CRANK_SURFACE


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Add Relations for Power Crank Surface


SHAFT_DIA

Click OK


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Create Displacement Pin Surfaces

Click on the Edit-Fill from themenu at the topSelect the References-Define atthe bottom of the screen

Select theCHAMBER_RIGHT datum plane for sketching and theCHAMBER_TOP datum planeas the Top reference, then click

SketchAdd the following references:DISP_ROD_PTS (top point)

DISP_ROD_PTS (middle point)


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Create Displacement Pin Surfaces (cont.)

Insert two circles as shown to the right.Dimension the diameter Make their radii equalClick , to finish the surfaces

Rename the surface to DISP_PIN_SURFACE


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Add Relations for the Displacement Pin surfaces

Enter Tool-RelationsAdd relations for:

Pin_dia

Click OK .


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Create Power Pin Surfaces (cont.)

Insert two circles as shown to the right.Dimension the diameter Make their radii equal to the reference radiusClick , to finish the surfaces

Rename the surface to POWER_PIN_SURFACE


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Create Stand Surface

Click on the Edit-Fill from the menu at the topSelect the References-Define at the bottom ofthe screenSelect the STAND_RIGHT datum plane for

sketching and the CHAMBER_TOP datum plane as the Top reference, then click SketchAdd the following references:

CHAMBER_TOPCHAMBER_FRONTSTAND_TOP

Sketch the section shown at the rightMake sure you have the same dimensions, nomore no less, and the same values.

Click , to finish the surfacesRename the surface to STAND_SURFACE


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Select the sketch point button from the toolbar, when asked for the sketch plane select the CHAMBER_TOP plane and select the CHAMBER_RIGHT plane as the RIGHT reference. Click sketch from the menu.Select the following references-

CHAMBER_FRONT CHAMBER_RIGHT

Place the datum point usingconstruction line and constructioncircle and dimension as shownSelect to finish the point

Sketch datum points


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Hold down the CTRL button and select the CHAMBER_TOP datum planeand the point you just created.

Create Chamber Bolt Axis

Select OK

Rename thefeature to

CHAMBER_BOLT _AXIS


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Right click on the point created and select Hide

Hold down the CTRL button and select the point created and theCHAMBER_BOLT_AXIS

Right click and select Group

Rename the group CHAMBER_BOLT_LOCATION

Create Chamber Bolt Group


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Add Relations for the Chamber Bolt Location

Enter Tool-RelationsSelect the CHAMBER_BOLT_LOCATION groupfrom the model treeAdd relations for:

Chamber_dia+3/8

Click OK .


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Select the sketch point button from the toolbar, when asked for the sketch plane select the surface shown below and select the POWER_RIGHT planeas the RIGHT reference. Click sketch from the menu.Select the following references-

CHAMBER_FRONT POWER_RIGHT

Sketch datum points


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Place the datum point usingconstruction circle and dimension as shownSelect to finish the point

Sketch datum points


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Create Power Bolt Axis

Select OK Rename the feature to POWER_BOLT_AXIS


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Hold down the CTRL button and select the point created and the POWER_BOLT_AXIS


Rename the group POWER_BOLT_LOCATION

Create Power Bolt Group

Add R l i f h P B l L i


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Add Relations for the Power Bolt Location

Enter Tool-RelationsSelect the POWER_BOLT_LOCATION group from themodel tree

Add relations for:Power_piston_dia+7/16

Click OK .


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Sk h d i


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Place the datum point as shownSelect to finish the point

Sketch datum points

C Gl d l A i


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Create Gland Bolt Axis

Select OK Rename the feature toGLAND_BOLT_AXIS

C Gl d B l G


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Hold down the CTRL button and select the point created and theGLAND_BOLT_AXIS


Rename the group GLAND_BOLT_LOCATION

Create Gland Bolt Group

Add R l ti f th Gl d B lt L ti


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Add Relations for the Gland Bolt Location

Enter Tool-RelationsSelect the GLAND_BOLT_LOCATION group from themodel tree

Add relations for:Disp_rod_dia+7/16

Click OK .

Sk t h d t i t


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Select the sketch point button from the toolbar, when asked for the sketch plane select STAND_RIGHT and select the CHAMBER_TOP plane as theTop reference. Click sketch from the menu.Select the following references-

CHAMBER_FRONT STAND_TOP

Place the datum point as shownChange the dimension values as shownSelect to finish the point

Sketch datum points

C t B i S t B lt A i


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Hold down the CTRL button and select the STAND_RIGHT datum planeand the point you just created.

Create Bearing Support Bolt Axis

Select OK Rename the feature to BEARING_SUPP_BOLT_AXIS

C t B i S t B lt G


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Hold down the CTRL button and select the point created and the BEARING_SUPP_BOLT_AXIS


Rename the group BEARING_SUPP_BOLT_LOCATION

Create Bearing Support Bolt Group

Sketch datum points


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Select the sketch point button from the toolbar, when asked for the sketch plane select CHAMBER_TOP and select the CHAMBER_RIGHT plane asthe Right reference. Click sketch from the menu.Select the following references-

CHAMBER_FRONT STAND_RIGHT

Place the datum points as shownChange the dimension values as shownSelect to finish the point

Sketch datum points


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Create Stand Bolt Group


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Right click on the points created and select Hide

Hold down the CTRL button and select the point created,STAND_BOLT_AXIS_1 , and STAND_BOLT_AXIS_2


Rename the group STAND_BOLT_LOCATION

Create Stand Bolt Group

Save skeleton file


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Save skeleton file

Save and close the skeleton fileSave and close the layout fileExit Pro/EAt the command prompt type:

purge

Documents

Skeleton Modeling