In the Woodworking industry, laser scanners and touch probes have been used for some time for digitizing objects, but due to severe technical or practical limitations, neither has seen significant use in the market. Software and CNC machine technology already exist to take advantage of 3D digital models, so digitizing has been the weak link in the process. The recent introduction of the FastSCAN to the woodworking market has changed that, and allows woodworkers to leverage digital technology to increase their productivity and get more return on their CNC investment.

Introduction
3D laser scanners were first developed about 30 years ago. It has only been in the last 10 years that costs have come down, and the scanner designs simplified to the point where they are now beginning to see wide spread use in industry. Commercial and Medical markets and their applications for 3D laser scanning now include:

Market                                     Application

Art & Cultural Preservation    Replication, Restoration, Digital Archiving
Aerospace & Automotive       Reverse Engineering, Rapid Prototyping, Quality Control
Entertainment                         Animation, Model Making, Special Effects
Medical                                   Prosthetics & Orthotics, Cosmetic Surgery, Burn Masks
Woodworking                         Antique Restoration, Custom Millwork, Furniture Design

In the Woodworking industry, laser scanners and touch probes have been used for some time for digitizing objects, but due to severe technical or practical limitations, neither has seen significant use in the market. Software and CNC machine technology already exist to take advantage of 3D digital models, so digitizing has been the weak link in the process. The recent introduction of the FastSCAN to the woodworking market has changed that, and allows woodworkers to leverage digital technology to increase their productivity and get more return on their CNC investment.

The Basics of the Work Flow

Scan It – The FastSCAN wand sweeps over the object much like spray painting and creates what is called a “point cloud”, a computer model consisting of thousands of x,y,z data points.

Tool Path It –   The point cloud is typically converted to another format for use with modeling or engineering software (more on this later). In the case of woodworking, the file is used to generate a tool path for the CNC machine to mill a replica of the object.

Mill It – Scan data can be sent to 3, 4 or 5-axis CNC machines.

Pros and Cons of Digitizing Methods

Touch probes – A stylus is put in contact with the object and a data point is recorded. The stylus is moved to another position and another data point recorded and so on, until enough points are taken to create a point cloud that resembles the object. This can be extremely time consuming, and prone to errors.

Attempts have been made to automate the process by using the CNC to move the stylus over the object.  It does work, but most agree it is difficult to use, is not practical except for the most basic (and small) objects, and above all, takes the CNC out of production.

Pros

  • Relatively inexpensive         ($4000 – $12,000)
  • Expensive models can be very accurate

Cons

  • Very time consuming
  • Process prone to errors
  • Not practical for complex shapes (like carvings)
  • Limited range (small objects only)
  • CNC mounted versions take CNC out of production

CNC mounted laser scanners – Any laser needs to know where it is in 3D space when moving about and measuring the object’s geometry. The first laser scanners used in the woodworking industry relied on the CNC as the coordinate system. In other words, the laser scanning head was mounted on the CNC, and the CNC moved the scanning head back and forth across the object. This also works, but again is difficult to use (especially on the software side) and takes the CNC out of production. For these reasons this type of laser scanner has seen very limited acceptance in the market.

Pros

  • Can be very accurate
  • Can scan large objects

Cons

  • Takes CNC out of production
  • Software integration with CNC can be complex, difficult to set-up
  • Not portable

Engineering Scanners – The laser scanning head is mounted on the end of a precision articulating arm (used to measure where the head is in 3D space). The accuracy of these scanners is excellent and is the primary reason they are widely used in engineering applications. They are also very expensive, most starting at about $150k, but quickly approach $250k or more. The articulating arm also restricts the range of movement, and hence the variety of objects that can be scanned. It is also not very portable.

Pros

  • Very accurate

Cons

  • Price, $150 – $250K
  • Complex set-up
  • Limited range of movement
  • Not very portable

FastSCAN Product Profile

FastSCAN was developed 10 years ago as the world’s first hand-held 3D laser scanner. Its first major application was in the fabrication of prosthetics and orthotics. It has since become the industry standard for creating custom fit artificial limbs, with over 800 units in use over the past 5 years.

Interestingly, 3D scanning for woodworking uses the same work flow as the process of fabricating a mold for a prosthetic limb: scan the object (in this case an amputee’s residual limb), convert the scan file to a tool path and carve the replica on a CNC. There are several aspects of the FastSCAN demonstrated by the prosthetics application that are worth noting for woodworking as well:

–  Ease of use. The FastSCAN is used by a clinician, not a doctor or nurse. These clinicians, although trained in prosthetic fitting are not typically laser and digital technology savvy. Yet, hundreds use the FastSCAN everyday.
–  Accurate. A prosthetic limb stays attached by suction, therefore the prosthetic socket must be accurate to within a millimeter.  The FastSCAN is accurate to 0.5mm (.020 in.)
Reliability. Over 800 units in the field for this application alone, the system is field proven to be extremely reliable and is backed by a one year warranty
–   Portable.

The system packs into a briefcase size, hard shell case.

And for woodworking, there are several other benefits:

–  It is hand-held. Like a spray paint gun, you can move around an object freely, even get up on a ladder to scan architectural features of a building or home.
–  It uses industry standard software file formats. Whether you are using a modeling program, CAM program or CAD program, the FastSCAN can provide the compatible file for use in that program.
–  It can help keep your CNC loaded with jobs. CNC machines can be extremely productive, but only if they have digital input. Getting hand carved or custom made objects into tool path format has been the bottleneck. FastSCAN solves that and helps make your CNC more productive and increase the return on investment.
–  It is not just for replication. Once an object has been scanned, one can bring the file into modeling programs and make design or artistic changes before sending it the CNC.

Software Considerations

For most woodworking applications the process of converting the scan file to tool path is made simple by the many available off-the-shelf CAM programs. Getting the scan file into the CAM program is very simple and straightforward. The scan file is simply exported from FastSCAN as one of the common file formats used by CAM software, typically .STL or .DXF. The file can then be imported into the CAM software which is then used to generate the tool path.

The process described above is simple and works well when scan files are used only for replicating an object. If design or artistic changes are needed prior to milling, the process gets much more involved and cannot be covered with reasonable detail in this document. But it can be mentioned that this type of work can only be accomplished with either 3D modeling software (like Rhino, or Geomagic) or with CAD software (such as Solidworks or AutoCAD). Of these two types, 3D modelers work with organic shapes (such as hand carvings) much easier than CAD programs. CAD programs are better suited for geometric shapes (straight lines, circles, squares, etc.).

Case Studies and Links

http://www.polhemus.com/?page=Scanning_Case_Studies_Honeoye_Woodworking

http://www.polhemus.com/?page=Scanning_Fastscan

http://www.polhemus.com/?page=Scanning_Applications_Wood_Working

http://www.cadinfo.net/editorial/unocad.htm