by Robert Jaquiss
From the Editor: Robert Jaquiss is an access technology specialist at the International Braille and Technology Center for the Blind. He has a strong interest in tactile graphics. The following article provides a great starting point for those who need to know about this important subject. This is what he says:
This article briefly discusses the need for and describes technologies that can be used to produce tactile materials. Some pricing is included for the equipment discussed, but it is subject to change.
Tactile materials have been used to educate the blind since the late eighteenth century. Blind and visually disabled students are challenged when studying science, technology, engineering, mathematics, social sciences, and the arts. Sighted students have access to a wide variety of images in books, videos, and the Internet, but blind students must rely on text or verbal descriptions or the occasional tactile graphic. Adding to the difficulty faced by these students is the fact that depictions of three-dimensional objects in two dimensions can be difficult to understand.
Consider the structures of molecules in chemistry; anatomical structures; the shapes of vehicles--aircraft, boats, ships or spacecraft; simple and complex geometric forms; the shapes of dwellings used by indigenous populations like tipis, hogans, yurts, etc.; and archeological, anthropological, and other cultural artifacts. For some of these examples it is possible to purchase commercially available models. Kits exist for demonstrating the structures of molecules by assembling three-dimensional shapes representing atoms and connecting them with rods. Model shops can provide models of various vehicles, aircraft, etc. But, if a model cannot be easily obtained, what alternatives do educators have?
Producing tactile materials has until recently been a labor-intensive process. In the last few years, however, computerized techniques and advances in technology have made it possible to produce tactile materials with much greater speed. It is now easy to produce materials with complex shapes and even moving parts.
Commonly Available Technologies
Tactile materials are currently produced in a variety of ways; collage, thermoform, capsule paper, and embossers with graphic capabilities. Capsule paper and embossers have made it possible to produce line and shaded images rapidly. These techniques are useful and will continue to be used. New technologies, however, offer the possibility of producing materials unimaginable a few years ago.
The following new technologies, collectively known as Rapid Prototyping (RP), fall into two basic categories: additive and subtractive. Additive technologies, as the name implies, add material to a substrate. Subtractive technologies remove material from a block or sheet of material. Both are computer-based and require the use of graphical design software. When creating an object, computer software converts a model into layers. In turn each layer is processed to create an actual model. The capabilities of RP equipment are measured in terms of build envelope and layer thickness. Build envelope refers to how large a model the equipment can create. For example, a machine with a build envelope of 10 by 8 by 6 inches could create models ten inches long, eight inches wide, and six inches high. Layer thickness is how thick each model’s layer is. Thinner layers make it possible to produce models with finer details and better surface finish.
All but one of the devices in this category produce three-dimensional models. Some produce models intended to show concepts or to be used as casting patterns. Others produce usable plastic parts. The devices described below are priced beginning at $1,800. Some of the lower-cost devices are already finding their way into schools and are used by students studying Computer-Aided Design and Computer-Aided Manufacturing (CADCAM). The more expensive devices are feasible only for businesses, large schools, regional centers, or state agencies.
Roland LEC Printers
The Roland LEC family of printers produces tactile images including Braille, large print, and colored images. These printers are intended for use by signmakers, package designers, and anyone else needing to produce large images. The LEC-330 can print images up to twenty-nine inches wide on sheet-fed or roll-fed material. An included cutter and creaser allows for the cutting of parts in various shapes. Package designers use this device to print and cut out a piece of tagboard that can be folded into a box, thus creating a 3D object.
The LEC printer deposits ultraviolet-cured ink which can be printed in layers, and therefore the images can have a tactile feel. Braille characters are available as a font, so Braille is easy to produce. The LEC can handle applications needing different-sized dots or different spacing of the Braille dots with no problem. For example, Micro Braille such as that used in Japan is easily produced.
The LEC-330 can print one hundred square feet per hour, price: $60,000.
The LEC-540 is, as its model number implies, a larger machine, capable of producing images up to fifty-two inches wide, price: $70,000.
The LEF-12 is a small printer and can produce images twelve inches square on sheets or objects up to four inches thick. The LEF-12 is targeted at the awards industry, price: $30,000.
3D Systems produces a wide variety of RP devices. These range from low-end equipment intended for schools to large, industrial-sized machines. The best known of 3D Systems’ technologies is stereolithography (STL). The process starts with a vat of liquid photo-curing epoxy. A platform in the vat is close to the surface of the epoxy. A computer-guided laser beam exposes part of the epoxy at the surface, solidifying it. After the first layer is created, the platform lowers slightly, flooding the area above the solidified layer with fresh epoxy. The process continues until the model has been created. The finished model is extracted from the vat, cleaned of excess epoxy, and then cured in an oven. The parts produced have a smooth, glossy finish.
Selective laser sintering (SLS) uses powdered material deposited in layers. After a layer of powder is deposited, a computer-guided laser heats selected areas to fuse the powder to form a solid layer. The process continues until the part is formed. SLS parts have a slightly rough finish.
3D Systems recently acquired SolidScape, which makes machines renowned for their fine detail. SolidScape machines use wax to create parts that can be used in lost wax casting.
3D Systems also recently acquired ZCorp, whose machines are known for their higher build speed. Zcorp models are created using layers of powder fused with liquid from an inkjet printer head. ZCorp models are often infiltrated with epoxy or other material to strengthen them.
The lower-cost 3D Systems products are suitable for schools and small businesses. The larger, higher-priced equipment is suitable only for large institutions or large businesses. Prices range from $5,000 for the Cube, which can create small objects, to nearly half a million for large, industrial-sized machines.
MakerBot offers the Replicator™ machine that can create plastic parts. The Replicator is targeted at the home hobbyist market. Its build envelope is 8.9 by 5.7 by 5.9 inches. Layer thickness 0.2-0.3 millimeters. Price: $1,749 and up, depending on options.
The Mcor Technologies Matrix 300 printer uses laminated object modeling (LOM) to create parts. A layer of paper is laid down and then scored. Subsequent layers are bonded together and scored. The result is a block. Excess paper can be removed, leaving the part. The parts have a woodlike feel. The build envelope is 10 by 8 by 5 inches. A major advantage of the Mcor system is the very low cost of consumables. The machine uses new, nonrecycled twenty-pound copier paper. Models can be left as is or dipped in a material similar to superglue to strengthen them.
The Matrix 300 printer is suitable for use in schools and small businesses. Mcor Technologies has an unusual pricing scheme. The price includes enough glue and cutter blades to run the unit for 365 days. Price for one year: $18,500 plus $4,000 shipping and training.
Objet machines are known for producing models with fine details. Objet printers use PolyJet™ technology. Liquid polymer is deposited and immediately cured with UV light. A gel support material is also deposited, making it possible to create complex geometries. The gel support material is washed away after the part is completed. The Connex family of Objet printers uses PolyJet Matrix™ technology and can deposit two different materials simultaneously. For example, it is possible to create plastic parts with rubber surfaces. The Objet 24 is suitable for larger schools or small businesses. The Connex 500 is suitable only for larger organizations.
Objet 24, build envelope: 9.45 by 7.87 by 5.9 inches, layer thickness: 28 microns. Price: $30,000.
Eden 350V, build envelope: 13.7 by 13.7 by 7.8 inches, layer thickness: 16 microns. Price: $158,000.
Connex 500, build envelope: 19.7 by 15.7 by 7.9 inches, layer thickness: 16 microns. Price: $266,000.
Stratasys machines deposit two different materials: ABS plastic and a support material, a soluble plastic. The materials are deposited as hot droplets. Stratasys calls this technology fused deposition modeling (FDM). When the soluble-supporting material is dissolved, the model is ready for use, so it is easy to create models with moving parts. Using ABS plastic allows creation of a fully functional model that can be used as actual parts. Stratasys machines range from small machines for schools to large industrial-sized machines capable of building models 24-by-36-by-24 inches. The higher-end Stratasys machines can deposit other materials such as polycarbonate.
Dimension BST 1200es: $24,900
Dimension SST 1200es: $32,900
Build envelope: 10 by 10 by 12 inches.
Layer thickness: 0.013 inches.
The subtractive process starts with a block of material from which material is removed to create the finished object. The most common means for doing this is to use a computer numerically controlled (CNC) milling machine. Two examples are the 2BOT and the Roland family of milling machines. These machines create debris that must be vacuumed from the machine.
The 2BOT accepts a block of material up to 12 by 12 by 2 inches and can cut foam, balsawood, and machineable wax. The 2BOT is unique in that the block of material is loaded into a frame that slides into the 2BOT like a drawer. A cover encloses the work area, creating a safe machine. The 2BOT has a high-speed cutter that closely resembles a drill bit. The cutter removes unwanted material from the block. If the model is to be cut on both sides, the frame is removed and flipped over so that the back side of the model can be completed. The finished piece is still attached to the frame by small tabs of material that can easily be removed. The 2BOT is fast and can make models quickly. The downside to this speed is that the models lack fine detail. The 2BOT is easy to use and is being marketed to schools and to those who want concept models. The low cost of materials makes the 2BOT very attractive to schools. Price: $11,000
The Roland MDX40A accepts blocks of material 12 by 12 by 4 inches and can cut foam, acrylic, wood, machineable wax, and soft metals such as brass and aluminum. Because the Roland machines accept different size cutters, it is possible to create models with very fine detail. The MDX40A is also enclosed for safety. The workpiece is mounted on a table that moves back and forth. The cutter moves from side to side. Dowel pins can be used to align the workpiece if it is necessary to cut both sides of the model. The MDX40A is much slower than the 2BOT. The benefit is that it produces extremely well-finished parts. The MDX40A is more versatile in what it can do. Roland has other milling machines such as the MDX20 for small parts and the MDX540 for larger parts. The low cost of materials makes the MDX40A very attractive to schools. Price: $9,000
Using RP Equipment
Designing a model from scratch requires the use of computer-aided design (CAD) software. AutoCAD and ArtCAM are two well-known software packages. Google’s SketchUp is a much simpler software package.
It is also possible to find free files online or purchase files of models. Common file formats include OBJ, STL and DXF. A short list of libraries is:
1. 3D Science.com; this site, operated by Zygote Media Group, sells science-related models, <http://www.3Dscience.com>.
2. Flat Pyramid; Flat Pyramid sells a wide variety of 3D models, <http://www.flatpyramid.com/3D-models>.
3. Google Sketchup 3D Warehouse; this site has a wide variety of files contributed by the general public, <http://sketchup.google.com/3Dwarehouse>.
4. SolidWorks; this site has a wide variety of hardware and mechanical parts, <http://www.3Dcontentcentral.com>.
5. Castle Island Co.; Castle Island Company has an extensive list of model repositories, <http://www.additive3D.com/sw1_lks.htm>.
By its nature CAD software is graphical and is not very accessible except to blind people who can use screen magnification. I am totally blind and have used some of the software supplied by Roland for operating the Roland MDX40A, milling machine. It is possible to open and send files to the milling machine. It is also possible to set up the MDX40A without sighted assistance. In addition, I have printed images, scanned them with a scanner, and then created an engraved copy. I used this technique to create large images of the 2009 Louis Braille coin.
There are devices for scanning 3D objects. Like document scanners, 3D scanners create datafiles usable by various CAD applications. Some 3D scanners resemble microwave ovens. The object is placed on a rotating table and scanned as the table turns. Other scanners are like cameras and mount on tripods. Given the appropriate technology, it is possible to scan objects with details as fine as those on coins or as large as Mount Rushmore.
This article describes a number of options for producing three-dimensional models and is intended to provide a starting point for anyone interested in this subject. Use of three-dimensional models will enhance learning for both blind or visually disabled students and their sighted peers.
A MakerBot Replicator has been ordered for the IBTC, and a Roland MDX40A milling machine will follow in the future. What will we do with this equipment? We will create some sample models to show to those visiting the IBTC. We will make models to support the educational programs conducted by the Jernigan Institute. And of course we will demonstrate this equipment to our visitors. Inkprint printers and Braille embossers put our words on paper. In the same way RP technology will make images real.
Company Contact Information
Listed below are the companies mentioned in this article and their contact information:
2BOT physical Modeling Technologies
17455 NE 67th Court, Ste 110
Redmond, WA 98052
Phone: (425) 869-5035
Fax: (425) 484-6472
Email: [email protected]
3D Systems Corporation
333 Three D Systems Circle
Rock Hill, SC 29730
Phone: (803) 326-3900
MakerBot Industries LLC
87 3rd Ave.
Brooklyn, NY USA 11217
Unit 1, IDA Business Park
Ardee Road, Dunleer,
Co. Louth, Ireland
+353 41 6862800
5 Fortune Drive
Billerica, MA 01821
Phone: (877) 489-9449
Fax: (866) 676-1533
Roland DGA Corporation
15363 Barranca Parkway
Irvine, California 92618
Phone: (949) 727-2100
Toll free: (800) 542-2307
7665 Commerce Way
Eden Prairie, MN 55344
Phone: (800) 937-3010
(888) 480-3548 (Information Line)
Fax: (952) 937-0070
Additional Useful Information
Tactile Pictures: Pictorial Representations for the Blind, 1784-1940
Author: Yvonne Eriksson
Publisher: ACTA Universitatis Gothoburgensis (January 1998)
BST systems require users manually to remove plastic support material. Models with moving parts cannot be created.
SST systems use a liquid bath to remove support material. Models with moving parts can be created.
Autocad website: <http://usa.autodesk.com/autocad/>
ArtCam website: <http://www.artm.com>
Google SketchUp website: <http://sketchup.google.com>