By Gerald Davis, Contributing Writer
Iwas once a job shop owner. Our mission was to add value to raw inventory, then to profitably deliver that valuable inventory to our customers.
In my case, the raw inventory was sheet metal.
Over time routine material processing evolved and
expanded to include machined billet and a little bit
of plastic work. The investment in capital equipment matched or exceeded the customers’ expectation for precision and fine aesthetics.
In 2004, with 20 years of experience in fabrication, I retired and turned the shop over to better
management. My interest had shifted from fabrication to design. The first customer of my industrial
design practice is still sending me projects and has
graciously allowed me to use one of its products in
When PMI Was PDF
Figure 1a is an image of a machined steel part.
Fabricators in the machining trade often receive
and use 3-D geometry in the process of developing machine control programs. To assist in verifying
that the product coming off the mill is correct, a fabrication drawing may be prepared—Figure 1b, for
example. This PDF has dimensions, finish requirements, and declarations of ownership that are otherwise difficult to show in imported 3-D geometry.
With the goal of having a paperless fabrication
shop, a fabricator can rely on 3-D models, which
have product manufacturing information (PMI) embedded in them. As a happy coincidence, most of
the work required to prepare a 2-D fab drawing results from that PMI. Figure 1c shows some dimensional information, as well as a form with notes and
Suppose that the paperless future has arrived!
PMI, as hinted at in Figure 1c, has eliminated the
need for 2-D drafting, as represented in Figure 1b.
The modern drafting department is now tasked
more often with preparing illustrations as opposed
to dimensioned line drawings. Either way, it is just a
process for adding value to inventory.
Common ground exists between traditional drafting and product illustration. The inventory to work
with is 3-D geometry. Experience with PDF/PMI
helps with efficiency. The discipline required for
preparing 2-D drawings is not much different from
setting up camera shots on a consistent basis.
Illustrating the CAD Way
Figure 1a is a view of a 3-D model using a camera’s
perspective, shadows from the environment, and
resulting hues from materials and finishes. Setting
up such a view can be accomplished in just a few
minutes, but the mouse clicks and menus are not
often used in 2-D drafting. It helps to practice.
The assembled product illustrated in Figure 2a
puts the ramp from Figure 1a into context. Several
other parts are bolted and wedged together. Those
items have been exploded in Figure 2b, which gives
a hint about how the assembly goes together.
Perhaps the most tedious aspect in preparing
Figure 2b is the addition of path lines. One must
click to place each end of each line. Even so, the
preparation of exploded views is a routine skill from
With product illustration as the design intent, the
twist is to plan and sequence the explode steps in
3-D CAD. When you are just making an exploded
view for a 2-D drawing, the sequence of explode
steps is pretty much irrelevant. Anticipation and
plotting are subtle CAD skills that lend competitive
advantage when making videos of animated assembly collapsing.
As another CAD tip, drama is sometimes useful
for revealing details of an assembly. The dramatic
example in Figure 3a is of transparent aluminum
and a distinctive point of view. Figure 3a might be
the exact image needed in a product brochure.
Here’s a CAD tip: Rename the camera and save its
locked position. As the CAD model evolves and the
illustration needs to be updated, just switch back to
that saved camera position. In Figure 3b we see
that two cameras have been set up. Camera2-Fig3A
has been selected. Selection of a saved camera view
is how the view of the model in Figure 3a may be
3-D CAD Being Wordy
Once the image is rendered, it needs to be saved in
a digital format. This is not a new concept for the
CAD jockey. However, anticipating how the digital
image file will be used can be a real advantage for
the seasoned pro.
Consider the task of making illustrations for a
product brochure. When the design changes in CAD,
we want the illustrations in the brochure to update.
Efficiency is our competitive advantage. In terms of
workflow, the core concept is to digitally link the 3-D
geometry to the product brochure.
Read more from Gerald Davis at www.thefabricator.com/author/gerald-davis
Shop technology and
3-D CAD: From the model
to the product literature
Tips and tricks for preparing product illustrations
An example of a product manufactured from steel is
shown. Starting with a STEP file import, materials, environment, and camera were added. Starting with the
rendering, the CAD jockey used an add-on to the 3-D
CAD software to create this illustration.
An example of a 2-D PDF fabrication drawing is shown.
The part from Figure 1a was dropped into the drawing
template to reveal the product manufacturing information (PMI) embedded within the part.
The 3-D CAD software can be used to examine PMI. On
the right is a data entry form for specifications and notations. All of the information required to fabricate this
part is embedded in the model. In a paperless world,
does this PMI make Figure 1b obsolete?
This is an example of an assembly. The 3-D CAD workstation makes it easy to change the transparency of
components to reveal hidden details. This illustration
helps to explain where the item from Figure 1a is used.
This is an example of an exploded view of an assembly. 3-D CAD makes a simple task of the inspection and
animation of exploded views. Sketching the paths is
tedious, but the result helps explain the relationship