Rob Glassburn Blog - 3D Laser Scanning, GD&T & Reverse Engineering

New Structured Light Scanning Tool Enhances Our 3D Scanning Service

noreply@blogger.com (Rob Glassburn, PE) — Wed, 25 Jan 2012 16:25:00 +0000

At 3D Engineering Solutions we’ve recently added another tool to our 3D laser scanning services. We now regularly use a new structured light scanning device—the Steinbichler Comet L3D. It uses LED blue light technology and can capture up to two million points in 1.5 seconds. We’ve already employed the technology for turbine blade and impeller inspection, and mold and tool making. The structured light scanner is useful for 3D scanning, rapid manufacturing and design, quality control, tool making, and reverse engineering. It’s great for capturing anything with a lot of sharp edges and detail—even small medical instruments.

The structured light scanner is easily portable, and the blue light technology presents many benefits over the older, white light technology. Advantages include a longer-lasting light source and lower temperature influence due to LEDs, the ability to scan a well-lit room, and the ability to filter out other light present when capturing an object.

One way we expand the usefulness of the Steinbichler Comet L3D is by integrating it with photogrammetry, which increases our ability to measure larger parts. We can capture entire vehicles with micron-accuracy. In addition to the photogrammetry accessory, we also have a 2-axis turn table, which allows for automated inspection.

I invite you to leave a comment below. Also, you can follow me on Twitter to keep current with the latest feats and projects of 3D Engineering. http://twitter.com/RobGlassburn.

3DES Captures Cincinnati's Union Terminal Using Long Range Laser Scanning

noreply@blogger.com (Rob Glassburn, PE) — Thu, 17 Nov 2011 21:25:00 +0000

Recently my company—3D Engineering Solutions—used high-speed long range laser scanning to capture precise measurements of Union Terminal—a National Historic Landmark and massive art deco building here in Cincinnati. The Faro laser scanner we used is small, portable, and has a wide-range of uses. For this project we captured Union Terminal’s measurements with millimeter-accuracy in just hours and as millions of data points. The 53 gigabytes of data generated is now being used for Building Information Modeling (BIM) in aggregation with other software, giving architects and engineers ability to create simulations of how best to preserve the 80 year old structure. A fly-through video showing the expansive building and its detail was also created. Click here to watch the 3D fly-through video

Mapping a facility is just one example of what long range laser scanning can do. Our tool can be used to accurately inspect structures or to capture crime scenes. Even if it’s pitch-black outside, the scanner can read tire treads, residues and surface textures.

3D Engineering Solutions acquired the long range laser scanner in December 2010 and we’ve employed its technologies for several projects now, including bridge inspection and measurement for the renovation of a large power plant facility. This tool can capture objects up to 120 meters and with speed up to 976,000 measurement points per second. We’ve got several projects using the Faro scanner in the works right now. Stay tuned for more information about how we’re putting this technology to work.

I invite you to leave a comment below. Also, you can follow me on Twitter to keep current with the latest feats and projects of 3D Engineering at http://twitter.com/RobGlassburn.

How to Properly Use Point Probes on FARO CMMs

noreply@blogger.com (Rob Glassburn, PE) — Thu, 03 Nov 2011 19:17:00 +0000

Covered Topics: Point Probe Accuracy, Sharp Tip Point Probes, On-Site Measurement, How to Accurately Measure Trim Lines, Creating Non-Standard FARO Probes, Using Multiple Probes in One Inspection Session, Changing Probes During an Inspection

Point probes are typically thought of as a very sharp point and are assumed to have zero radius. During a recent on-site inspection we discovered that this assumption is not the best one. We discovered the initial discrepancy when using one of our FARO arms and multiple probes in one inspection. We used a 3mm ball probe and a sharp tipped point probe. After calibrating and then setting up the reference frame and measuring a few features with the 3mm ball probe, we switched to the point probe, calibrated the point probe and began to continue measuring.

Typically we do not need to change probes during measurement. However, for this case we needed to probe trim lines that followed a non-planar path. So using a ball probe would have introduced a larger error in the non-planar areas. This is because the trim lines were not on a simple plane. So we could not compensate the ball probe with a simple plane. The trim lines that were at an angle would have required a separate probed plane for each point (not practical from a time standpoint) or use a compensation point (already known to yield poor accuracy).

It was shortly thereafter that some of the results from the point probe started to not make sense. As a check we created some features to compare to previous features and discovered a difference of 1.3mm to 1.5mm in values measured with the 3mm ball probe and sharp point probe. At first we thought that the part had been bumped or the tripod that the FARO was mounted on was bumped. We quickly eliminated these as possibilities by retrying and being especially cautious of these items. No resolution. We thought that it might be a software issue or a hardware issue (although not likely).

Once we brought the arm back to the lab and set everything up on one of our granite surfaces we determined the differences to be on the order of 0.5mm consistently. We believe the initial 1.3-1.5mm values came from one of several possibilities: the number of points used during calibration (about 200) versus the greater than 500 points used back in the lab and standard practice, the granite surface and nice clamping arrangement.

This still left us with the dilemma of why there was a difference at all. We had two different point probes available to us. We tried both and found that each had a different off-set from the ball probes – but consistent. The second point probe was an older one salvaged off of an older arm. Both are pictured below shown on an optical comparator. Once we saw how different the two probes were we understood why there might be a difference.

FIGURE 1: Optical comparator view of 2 point probes. A newer one (left) and an older one (right). Note the radius on each tip.

With this information and a little brainstorming we came up with the now obvious fact that the point probes do not have a zero radius! The assumption to date had been a zero (or very close to zero) radius. This is clearly not so as seen in Figure 1. In fact the PolyWorks plugin from FARO shown in Figure 2 below shows a zero value for the radius (Probe Diameter).

FIGURE 2: The standard plugin for a point probe which shows a zero value for the radius of the probe (Probe Diameter).

FIGURE 3: The same plugin once the value of the radius has been changed from zero to our estimated value. The question mark and generic probe appears whenever the standard probe values have been changed.

After this revelation, the next step was to determine the radius to use. We used a 1-2-3 block to probe all 3 principle directions (X-Y-Z) and determine what value to use. And in fact, each difference was very consistently offset from the ball probe measurement. This consistantly equal offset value in each direction was another indication to us that in fact we needed to use a spherical radius value for our point probes.

We still had some small variations in the readings (X-Y-Z), so we took an average value and input this into the radius for the point probe (Figure 3). The result – Success!

The difference values between probing with a ball probe and the point probe (with radius value) were very good. We saw differences from 0.004mm to 0.015mm. We will work to tweak these values a bit but feel as though we now have a good process to work with.

In the past we had been told that the point probes were not very accurate or that we would not be pleased with the results from using one. We believe that we have figured out the missing link for achieving reasonable accuracy with this probe.

Note that since these probes are all relatively sharp, you should recheck the radius of your sharp point probe before each inspection to be sure that it has not worn significantly or developed a burr. Either might give you erroneous results. We suggest probing a 1-2-3 or similar block and looking at the X-Y-Z values taken on multiple faces to deterimine a proper spherical radius to use.

3D Laser Scanning and CAD Modeling Bring High Tech Violin and Cello Tailpieces to Market

noreply@blogger.com (Rob Glassburn, PE) — Wed, 26 Oct 2011 22:34:00 +0000

Using 3D laser scanning and CAD modeling technology, 3D Engineering Solutions helped The Frirsz Music Company bring its patented violin and cello tailpieces that improve sound and performance to the marketplace. These lighter than wood tailpieces comprised of aerospace metal alloy can now be manufactured for musicians everywhere because of the 3D scanning services and design expertise provided by 3D Engineering Solutions.

The original tailpieces underwent precision scanning, which captured the objects’ high-density geometry and compound surface curvature. 3D Engineering’s 7-axis, laser measuring devices and specialized software allowed engineers to collect data as millions of points and create point cloud files. That data was then used to generate highly accurate 3D CAD models of the violin and cello tailpieces.

“To have an opportunity to replicate in 3D CAD one-of-the-kind violin and cello tailpieces is a great example of bringing an entrepreneurial vision to life,” noted 3D Engineering Solutions VP of Operations, Rob Glassburn. “We helped bridge the gap between inventor and production company, with the assistance of our CAD engineering team.” Senior 3D CAD Engineer Gene Hoppe’s experience in designing tools and fixtures in the automotive and aerospace industry provided the necessary skills to handle some of the complex manufacturing issues of this project such as draft, temperature coefficients, and material selection.