[Calvin Banman] The arm we are using runs with Delcam's Powerinspect
software. (http://www.delcam.com/) It has an option for "point
clouds" that you can export as an IGES file. Apparently this would
make reverse engineering easy, but our company was too cheap to spring
for that. I worked with one of our engineers and found a way around
it. We can still export our information in an IGES file, but for it
to be useable for solid modeling; we have to measure a number of
points in a straight line around the part. Then using as many of these
lines as required to give us the detail level engineering needs, they
can import the file into their CAD software, and create a solid model.
Obviously the more data the better the end result. I use magnetic
strips to give me a straight line that I follow with the probe, but I
tried one freehand just to see if it worked and it did. I just drew
some lines on the part and followed it as well as I could. I do the
point lines in a crosshatch or checkerboard pattern. The beauty of
the portable CMM arm is that you can measure parts of infinite size.
Some of our frames are over 20 feet long, and to measure them, we end
up doing about 8-10 leapfrogs (position changes on the arm).
[Jim Peck]I am really interested in the techniques you use to develop
the CAD models.
[Calvin Banman] http://us.romer.com/
I use one of these at work. We don't have the laser scanning
attachment. The reverse engineering option is extra cost and our
company didn't want to spring For it, but I have found a work-around
that lets me give engineering the data they need to do a CAD Solid
model from measurements I take. I know the Honda plant in Allison,
Ontario uses one of the Romer arms to measure body panel fit on the
cars they build. When I was getting my training on the older version
of the arm, I brought in a 360 cylinder head and digitized the
combustion chamber shape.
[James Peck] The May/June 2006 issue of Time-Compression Technologies,
www.timecompress.com, discusses the use of a handheld self-positioned
Laser scanner to scan a vehicle body to produce a 3D CAD model of the
vehicle body. The vehicle scanned was the T-Rex Manufactured in Quebec
For the purpose of doing FEA and using CMM's.
