1. Join us on Twitter: #AU2014
Modeling Basics for 3D Printing
Using AutoCAD®
William Work
CAD Manager

2. Who am I?
 Architect
 CAD Manager
I am an architect and CAD manager with a firm of more than three hundred professional staff working on projects spanning a wide
range of project types. On a daily basis, I work closely with the design staff providing impromptu one-on-one Q&A style
AutoCAD® support and tutorials. On a regular basis I develop and deliver structured classes. I have also worked directly with
resellers providing a variety of consulting services throughout the United States. These services have included AutoCAD
deployment and customization, on-site training, and CAD standards development and documentation.

3. What’s in it for you?
My goal is that you will:
 Understand the fundamentals of 3D printing.
 Be able to create 3D geometry that is suitable for 3D printing.
 Validate your 3D model.
 Output the required STL format file.
We’ll do all of this entirely within AutoCAD!

4. How Will We Get There?
The first part of my talk will be an introduction to the 3D modeling capabilities of
AutoCAD particularly related to 3D printing. Along the way I will demonstrate
some of the fundamentals.
The second part will be a step by step case study of the creation of a 3D model
for 3D printing.

5. But first…
“…,the most transformative technological innovation of our time,…”
Hemispheres Magazine, November 2014

6. Why Use AutoCAD For Creating 3D Geometry?
 AutoCAD fully supports 3D geometry.
 AutoCAD’s 3D command set is robust.
 You don’t need to learn another software application.
 You don’t need to purchase another software application.

7. The Basics of 3D Printing

8. What is 3D Printing?
 3D printing is a fabrication process
whereby an object is generated
directly from a 3D computer model.
 It is an additive process that lays
down successive layers of material
under computer control.
 The input to the 3D printer is an STL
file that you generate from your 3D
computer model.

9. Best Practices
Modeling for 3D printing is not fault
tolerant.
 Faces must meet cleanly.
 The model must be watertight.
 Small elements will need to be
exaggerated.
 The model must be one piece.

10. Your AutoCAD Workspace
Make the 3D Modeling workspace
current.
The handout lists ten useful system
variables. Here are two important
settings.
 Osnapz=0
Prevents osnaps from auto-
projecting to the XY plane.
 Solidcheck=1
Turns on 3D solid validation.
Both of these are the default settings.

11. Visual Styles
 Control how objects appear in a
viewport.
 Many times changing from one
visual style to another will help you
better understand your model.
 Visual styles can be customized.
 Vpcontrol=1 will display the control
in the upper left corner of the
drawing area.

12. The AutoCAD 3D Tools

13. AutoCAD’s 3D Modeling Tools
AutoCAD allows you to model using
solids, surfaces, and meshes. In my
experience solids are well suited to 3D
modeling for 3D printing.
Closed meshes are also perfectly
valid.
Surfaces are not valid for 3D printing.
We will concentrate on solids.

14. AutoCAD’s 3D Modeling Tools
 Box
 Cylinder
 Cone
 Sphere
 Pyramid
 Wedge
 Torus
 Polysolid
Solid Primitives
Think of the solid primitives as your
basic building blocks.
Your model will often start with these
and then you will manipulate them in
various ways to achieve your desired
result.

15. AutoCAD’s 3D Modeling Tools
 Extrude
 Loft
 Revolve
 Sweep
Solids Generation
Solids can be generated from closed
objects that define profiles.
Using these objects you can easily
create many complex geometries.

16. AutoCAD’s 3D Modeling Tools
 Union
 Subtract
 Intersect
Composite Solids
Composite solids are created by
adding together, subtracting, or finding
the intersection of objects.
Often the object you are modeling will
begin with primitive solids and
generated solids combined with each
other.

17. AutoCAD’s 3D Editing Tools
 Presspull
 Imprint
 Shell
 Fillet or
Filletedge
 Slice
Solid Editing
AutoCAD offers several commands to
further edit your model. Use these
commands to directly manipulate
faces, edges, and vertices.

18. Cleaning and Validating Your 3D Model
Clean and Check options of the
Solidedit command.
Clean
Clean removes redundant edges,
vertices, and unused geometry from
your model.
Check
Validates your model. If your model
passes the check, this prompt is
displayed: “This object is a valid
ShapeManager solid.”

19. Creating Your Output File
Most 3D printers will want
an STL file. Use the 3dprint
command. That’s all there
is to it.

20. Case Study

21. Case study: Doric Column
What follows is a step by step
example of how a complex object
might be built using the commands
and techniques just described.

22. Step 1: Construction Guides
 Establish the centerline of the
column shaft.
 Draw guides for the diameter of the
shaft at both ends.
 Divide the defining circles into 20
segments.
 Draw guides for the radius and
location of one flute at both ends of
the shaft.

23. Step 2: Loft the shaft
 Using the guides for the shaft,
create the shaft by lofting.

24. Step 3: Loft the flute
 Using the guides for the flute, create
the flute volume by lofting.

25. Step 4: Array the flute volume
 Using a polar array, generate
volumes for the 20 flutes.

26. Step 5: Subtract the flute volumes
 Using a Boolean subtraction,
subtract the flute volumes from the
shaft.

27. Step 6: Place spheres for the
flute ends.
 Using the guides for the flutes,
place spheres at both ends of the
flutes.

28. Step 7: Array the flute end spheres
 Using a polar array, generate
spheres for the 40 flute ends (top
and bottom).

29. Step 8: Subtract the flute ends
 Using a Boolean subtraction,
subtract the flute end spheres from
the shaft.
 At this point the column shaft is
complete.

30. Step 9: Shell the column shaft
 To reduce the print time and the
amount of material used, apply the
shell command.
Within the context of the command,
remove the top face of the shaft.

31. Step 10: Capital and base guides
 Place guides for the capital and the
base in position.
 Extrude the plinth is horizontally.
 Revolve the base moulding around
the center of the column.
 Extrude the abacus downward.
 Extrude the abacus moulding
around the abacus.
 Revolve the capital moulding
around the center of the column. PLINTH
BASE
MOULDING
ABACUS
MOULDING
ABACUS
CAPITAL
MOULDING

32. Step 11: Completed project – but…
 The column looks complete but
would be more suitable for 3D
printing if the capital was separated.
As it stands the column will require
support material to handle the
overhang of the column capital
resulting in time spent for post-
process cleaning.

33. Step 12: Capital removed
 Remove and invert the column
capital.
 Created a stud within the column
shaft.

34. Step 14: Final step
 Subtract the stud from the column
shaft. Note that the stud is keyed to
ensure the proper alignment when
the column is assembled.
 Scale down slightly a copy of the
stud and place it on the column
capital.
 The union command is applied to
each model.

35. Sending the model to the
3D Printer
 The software application that comes
with the 3D printer allows you to
arrange the model or models on the
build plate for maximum efficiency.
 Note that this application offers an
estimate of the time and material
required.

36. Final 3D printed column

37. Thank you for your time.
I hope this brief seminar has encouraged you to go
forth and start exploring 3D modeling in AutoCAD.

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