T. Scott Rowe
An optical engineer shares
his notes on using rapid
to create lens mounts.
Rapid prototyping (RP) technologies have been around for more than
20 years. They are often used to develop
design elements for consumer products
such as ergonomic handles, skins, etc.
Yet rarely is much written about how
these technologies can be used to create
That’s why I decided to share my
experiences. I needed to develop a lens
mount quickly, with relatively loose
mounting requirements and tolerances.
It had to be lightweight, cosmetically
appealing, manually activated (like
a classic flip in/out lens mount), and
adjustable over a ± 1 mm location.
As a prototype, it would only be
used for preliminary evaluations, and
therefore it did not need to have a long
service life. It was an interesting challenge! I initially considered making it
out of an aluminum alloy. However,
this complicated the bearing design and
could limit the design shape. It would
also take longer to develop. An RP set
of parts straight out of Solidworks-generated mechanical design files (e.g.,
STEP, STL, etc.) served as the bearing
and the mechanism mount as well as
the lens mount. Based on the limited
14 | OPN Optics & Photonics News
processes are driven by
instructions that are derived
from 3-D CAD models.
life expectancy, I thought this might be
the way to go.
The main RP processes work by building up a component layer by layer, with
one thin layer of material bonded to the
previous thin one. There are several different processes, including:
c laser sintering
c fused deposition modeling (FDM)
c solid ground curing and
c laminated object manufacturing.
In addition, there are a number of
newer processes, such as ballistic particle
manufacturing and three-dimensional
Semi-transparent assembly of the bearing, detent and lens mount with lens. A simple sheet metal spring keeps the roller bearing up against he pivot bearing surface. A flanged shoulder screw (backside shown) holds the whole assembly together, but is not a bearing surface.
T. Scott Rowe
printing, that have recently appeared
on the market. These processes essentially start with nothing and end with
a completed part; this is in contrast to
conventional manufacturing processes
such as milling machines, which start
from a solid block of a substance and
cut material away to form the finished
part. Rapid prototyping processes are
driven by instructions that are derived
from 3-D CAD models. CAD technologies are therefore an essential enabling
system for rapid prototyping.
The processes use different physical
principles. However, essentially they
work either by using lasers to cut, cure or
sinter material into a layer, or by ejecting
material from a nozzle to create a layer.
The type of material used depends on the
process. Materials could include thermo-polymers, photopolymers, other plastics,
paper, wax, metallic powder, etc. For
this project, I relied on the FDM process
primarily due to my familiarity with the
material, vendors and processors.
Today, FDM materials include a variety
of acrylonitrile butadiene styrene (ABS),