By Gerald Davis
The invention shown in Figure 1a is repre- sented fairly well and is an intriguing image. However, it is difficult to assess the function
or scale of the mechanism. Figure 1b puts the device into a meaningful context by adding a familiar
prop to the scene—a classical guitar.
We wish to acknowledge Tim Johnson for allowing us to use his guitar accessory as a subject of discussion. This is the real deal. Tooling and manufacturing are complete. Johnson has customers and is
taking orders for this newly released accessory. His
website, www.guitarest.com, has more information
if you’re into playing classical guitar with comfort.
My role in this project included industrial design,
manufacturing, engineering, and graphic arts. While
working with Johnson to translate his inspiration into
a patented, and more importantly, marketable item,
I produced complete and accurate 3-D models of the
product line using mainstream 3-D CAD software.
Business and CAD Mix Well
The CAD data became vital to Johnson’s business
operation. As the design evolved, the consequences
to inventory were well-managed:
• The top-level bill of materials (BOM) was
valuable for identifying and purchasing
• The BOM also helped with creating a master
• Vendor activity, which involved a machine
shop, a sheet metal shop, a plastic shop, a
painter, a plater, and an assembler, was
coordinated using a spreadsheet that was
derived from the CAD BOM.
• The STEP files (and PDFs of 2-D fabrication
drawings) exported from those CAD models
were used to make the tooling for vacuum
forming as well as for the CNC machining and
laser cutting of the metal parts.
• The 3-D CAD models were used to create still
shots for Johnson’s printed literature. They’ve
been used again to create the images for this
With the creation of still shots in mind, please
compare Figure 1b to Figure 1c. Without the mannequin in Figure 1b, the leg rest remains mysterious. It might be some kind of repair clamp or sound
damper. (It is neither of those things.) We found that
the mannequin sitting in a chair made it easier for
the first-time viewer to appreciate the function and
appearance of the product.
Read more from Gerald Davis at www.thefabricator.com/author/gerald-davis
Shop technology and 3-D CAD:
Using props for adding scale to a presentation
Enough animation could lead to the creation of promotional videos
The use of a prop can make it easier to understand
what the product does. In this case, a guitar as a prop
gives a hint that the item in Figure 1a might be a guitar
This illustration shows the device supporting a guitar.
The context of thigh, leg rest, and guitar is informative.
The addition of a spotlight helps emphasize the point
This image is a zoom-out from Figure 2a. This change in
scale improves the appearance of texture on the shirt.
Cropping the mannequin leaves the guitar as the star.
The product is visible but may not be obvious to the
Showing the product without props definitely changes the center of attention.
The blank space is much
like the blank stares we got
when we showed this to the
focus group. In a slideshow,
toggling between Figure 2b
and Figure 2c works pretty
well. In animation, it creates a flash-bulb effect.
This image is a zoom-out from Figure 1c. Even
though the entire product line is visible, the
mannequin is the atten-tion-getter. The unrealistic features of the mannequin made this a rejected
This close-up image of the
armrest works well with
the forearm and guitar.
However, the “quick and
easy” texture that was applied to the shirt looks like
yellow tread plate instead
of cloth. This led to another rejected effort.
What good is a product illustration that might be cute
but does not inform?
Those props in Figure 1c, hombre.sldasm
and chair.sldprt, were downloaded from
www.3dcontentcentral.com. Acknowledgment to
Josemari de la Iglesia for the human poser and to
Tuyen Ha for the chair.
Figure 1d is a zoom-out from Figure 1c. We added a spotlight to bring the leg rest out of the shadows. We found Figure 1c to be more successful than
Figure 1d mostly because of the mannequin. The
“un-realism” detracts from the message. This scene
does, however, show both the armrest and the leg
rest in meaningful context.
Center the Attention:
Since up-close was good in Figure 1c, we tried the
same with the armrest in Figure 2a. The mannequin’s shirt is textured with yellow “tread plate.”
When viewed closely, the mannequin is a strange
combination of realism and poor choice of textures
for this scale of rendering. Figure 2b takes advan-