CAD for Hobbyists: PTC Creo Elements/Direct

Creo Elements/Direct
Creo Elements/Direct

Before starting the demo for my review of CAD for Hobbyists I had never used PTC Creo Elements/Direct before.  Years ago (about 10) I used PTC Pro/Engineer for a short while.  PTC Creo Elements/Direct is a decedent of Pro/E. A few years ago Pro/E was renamed Wildfire, later to be again renamed Creo.  The standard version of Creo is a parametric feature based modeling program.  I had initially assumed that Creo Elements/Direct was a stripped down version of Creo, I was wrong.

As the name of the program indicates Creo Elements/Direct is a direct modeling program and not a feature based editor.  3D shapes are created by pushing or pulling 2D sketches to add/remove material to the model.  These sketches are not used to be able to update the shape of the model at a later stage.  If you create a box and decide that at some point later you wish to decrease the size of the box, you grab one of the box faces and push it inwards directly updating the size of the model.  This direct modeling is much like sculpting.  Coming from my background of feature based modeling, I find this methodology frustrating.  I like to see the history of features that were used to create my 3D model and be able to go back in time to make changes as needed.

Sample Project

When opening Creo Elements/Direct you are presented with an empty file called a session.  Creo Elements uses sessions as a combination part/assembly file.

A new Session
A new Session

This blank session starts with a single part (which is empty) and a workplane.  Workplanes are used to create sketches on, but are only useful for creating a sketch, they can be deleted at any point in time without effecting the 3D model.

To start the bottle opener I first create a rectangle sketch.  By using the TAB key I can directly input the dimensions of the bottle opener body.

Drawing a Rectangle
Drawing a Rectangle

Pressing ENTER completes the rectangle drawing operation.  I prefer directly entering my dimensions using the TAB-TAB-ENTER sequence to create a rectangle of a given dimension.  You can also click and drag to make a rectangle and go back and add dimensions after the fact.   However, these dimensions are associated with the sketch that will be used to generate the 3D model and not the model itself.

Rectangle After Sketching
Rectangle After Sketching

With our rectangle that will be the bottle opener body created, we can now pull it into a 3D shape.

Using the Pull Command
Using the Pull Command

With the pull command you can either manually extend your 2D sketch into a 3D shape, or use the pop-up dialog to enter a dimension.  The TAB-ENTER key sequence also works to manually enter and accept the dimension for the pull.

Completed Pull Command
Completed Pull Command

With the bottle opener body created, I next wanted to add the opening that makes the bottle opener functional.  To do this, I created a new workplane on the top surface of the bottle opener bottle on which I would sketch the opening.

Creating a new Workplane
Creating a new Workplane

With this work plane I then began to sketch the opening.  I used the Line sketch object and used TAB-TAB-ENTER to manually enter both the length of the lines and the angle at which they are drawn.

Drawing the First Line of the opening
Drawing the First Line of the opening
Drawing the Second Line of the Opening
Drawing the Second Line of the Opening
The Completed Opening Sketch
The Completed Opening Sketch

With the sketch for the opening complete, I was able to use the pull command to cut the opening away.

Using Pull to Cut the Opening
Using Pull to Cut the Opening

With the opening complete, I now had 2 work planes with sketches that did not correspond to any geometry.  To clean up the display, I deleted these sketches.  To do so I clicked on the edge of the top workplane to select it.  With the plane selected, I right clicked to pull up a context menu.  This context menu allowed me to “Delete All 2D” which removes all sketches from the selected workplane.  I did this for both workplanes.

Deleting all 2D off the Workplanes
Deleting all 2D off the Workplanes

With the functional opening added to the bottle opener, I next needed to add the hole for the key ring.  Again, I would create a 2D profile on a workplane that I would pull to remove material from our 3D shape.  I used the TAB-ENTER sequence to manually enter the hole size.

Sketching Hole for Keyring
Sketching Hole for Keyring
Using Pull to Cut out the Keyring Hole
Using Pull to Cut out the Keyring Hole

With the hole created I did not have it accurately located.  To do this I would use the Dimension Command.  The easiest way to launch the dimension command is to select an edge of the model by left clicking.  This pulls up a context menu from which I can select the dimension tool.

Selecting Dimension from Popup Menu
Selecting Dimension from Popup Menu

With the an edge and dimension tool selected I then clicked the edge of the keyring hole to add the dimension.

Selecting the Keyring Hole to create a dimension
Selecting the Keyring Hole to create a dimension

To modify this dimension you simply double click it.  Where you double click on the dimension defines how the selected items will move.  In this case, clicking the left arrow will move the hole relative to the selected edge while clicking the right arrow will move the edge relative to the hole.  Clicking in the middle of the errors causes both features to move towards one another.

Selecting the Left Dimension Arrow
Selecting the Left Dimension Arrow

When you are editing the dimension it will show you which feature will be moving.

Keyhole dimension showing keyhole moving.
Keyhole dimension showing keyhole moving.

With the distance of the keyhole from the end of the bottle opener I added a second dimension to center the keyhole vertically.  With the keyhole properly positioned, I wanted to finish the bottle opener by adding a chamfer to the keyhole.  To add this chamfer I simply selected the edge of the keyhole causing a context menu to pop up.  From this menu I selected the chamfer command.  With the command open I was able to drag the chamfer to the appropriate size.  With the chamfer command active you can select any additional edges you would like to chamfer.  I selected the other end of the keyhole to also chamfer it.

Launching the Chamfer Command
Chamfer Command

With the keyhole chamfered on  both sides the bottle opener was now complete.

Completed Bottle Opener
Completed Bottle Opener

Conclusion

In my small sample size I found Creo Elements/Direct to be a more than capable modeling program.  I am personally not a fan of the direct modeling scheme (when compared to a feature based modeler that gives you a design history).  For a hobbyist who has never used a CAD program before direct modeling is probably a good way to get started with CAD.  For the experienced CAD user who is familiar with feature based modeling may find Creo Elements/Direct frustrating to use.

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