Digital Designs and Scientific Hardware - Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs - page 188

Peter Jansen 34 was a graduate student in the Cognitive Science Laboratory at McMaster
University in Canada. Among his many projects and accomplishments, he became interested
in 3-D printing and the RepRap project discussed in detail in Chapter 5 . He decided to take
the RepRap project to the next level and began designing and constructing prototypes for an
inexpensive 3-D printer based on selective laser sintering (SLS), which has the advantage of al-
lowing the creation of complex arbitrary geometries, with potentially much higher resolution
than fused filament deposition used in conventional RepRaps. In addition, in the long run, SLS
has the potential to lower overall costs and eliminate many of the known issues surrounding
the construction of durable and robust-fused filament extruders. The goal of his project is to
construct an open-source laser cuter with a large cut area (about 1 m 2 ), for about 5-10% of the
cost of a commercial system. 35 The design 36 shown in Figure 6.21 draws heavily from previous
open-laser cuter projects, such as the Buildlog 2X Laser Cutter 37 in using inexpensive alumin-
um extrusion and optics for most of the structural frame.
FIGURE 6.21 Open-source laser cutter.
In the Jansen design, however, the custom parts are 3-D printed from ABS (again radically
reducing the cost of machining custom parts). The printed parts represent about 10 h of total
printing time on RepRap and include parts such as NEMA17 motor holders that mount onto
T-slot, idler brackets, pillow block bushing mounts for motors, idlers, and shafts.
His project follows the free and open-source model outlined in Chapter 2 and he posted
designs for an open-laser cuter on Thingiverse. Even beter, the designs were made with the
hope that they would be of general utility to anyone printing out a large CNC system—not
just a laser cuter. This aspect is the most important for my group's research, as we suddenly
developed the urgent need to be able to weld thin sheets of plastic together. Here is why.
In collaboration with David Denkenberger, Michael Brandemuehl, and John Zhai at the
University of Colorado, I had demonstrated the ability to make an absurdly low-cost polymer-
based heat exchanger from plastic using an expanded microchannel design [ 27 ]. Polymers,
in general, have poor thermal conductivity and are not the obvious first choice for a heat ex-
changer material. Most current heat exchangers use metals and although microchannel heat
exchangers are currently used, and they have low material costs, the manufacturing tech-