Measuring the measuring systems - The latest dimensional tools take all of the guesswork out of frame repairs

Measuring the measuring systems - The latest dimensional tools take all of the guesswork out of frame repairs - ABRN (Automotive Body Repair News)

Collision Repair

Measuring the measuring systemsThe latest dimensional tools take all of the guesswork out of frame repairs

Publish date: Aug 1, 2008
By: Kevin Mehok
Source: Automotive Body Repair News

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(Photo Illustration by Michael Stassus, Photos Courtesy of Getty Images, Kevin Mehok)

More than a few years ago, I remember the best frame tech in the shop I was working for measuring a vehicle he had on the frame rack. This particular shop had just purchased a state-of-the-art laser measuring system. Being curious, I wanted to see how it worked. I walked over to the frame area of the shop and watched the tech measuring the vehicle with a tape measure and the old standby — his thumb. The new, very expensive measuring system wasn't even turned on. I asked the technician why he was not using the system. "It's too hard to set up, and I can get this job done before I get the machine turned on," he said. My thought was that he really wasn't well trained in how to use it, and his fear of the unknown kept him from using it.

Actually, I don't think this scenario is that unusual, and my belief continues today. During that time, there were several different types of professional measuring systems in use and quite a few seat-of-the-pants methods being employed. Training was kind of an afterthought, and consequently many vehicles were repaired improperly.

Photo of a dimensional printout from the genesis machine

In the past, "close enough" may have been good enough when measuring. With the vehicles built since the onset of the unibody, tolerances have been reduced to millimeters and in some cases, zero. Considering theses tolerances, it would be virtually impossible to correctly repair unibody/frame damage without a precise measuring method. Accurate frame and unibody repairs cannot be performed unless they can be accurately measured.

Better than the tape measure

Don't throw that tape measure away — it still serves a purpose in certain situations. If you're going to measure a unibody accurately, it needs to be done with the following:

a dedicated bench measuring system;
a mechanical universal measuring system; and,
a mechanical laser and computer laser/sonar system.

I will explain how each of these systems works, but initially we need to understand that measuring and pulling a vehicle are two different things. A universal frame rack, a floor system and a dedicated bench are all tools that help us pull and repair the unibody while it's being measured. They measure the damage, against control or reference points, while the vehicle is mounted to the apparatus.

The hang-on targets for a laser system.

Before the universal, the laser, computer and sonar systems came into prominence. Measuring was only two-dimensional. The advent of these systems provided the repairer with a three-dimensional measurement, insuring much greater accuracy. The three main control points that make up three-dimensional measuring are the vehicle centerline, its zero line and its datum line. These points indicate the vehicle height, length and width. All three of theses dimensions can be measured simultaneously using a computer or universal system.

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Kevin Mehok

Kevin M Mehok is the CEO of Crashcosts.com and a current board member for several other companies. In his nearly 30 years of experience in the collision industry, he was Operations Director for CARCARE Collision Centers, and Collision Centers of America. He also served as Regional VP for Collision Team of America, and has worked in similar roles with several other Chicago area consolidators, Gerber, (Boyd) and Cars. He can be reached through e mail at: k.mehok@comcast.net. Articles by Kevin Mehok

Comments from our Readers


Posted 2008-08-29 10:32:55.0
I have worked on all types of measuring equipment including Celette's bench system. What was not mentioned with the dedicated bench is that the measuring system also holds critical points in position during the pulling process. For example, as a front rail is pulled till a pin fits a factory hole, that hole is then held at the correct point during further pulling ensuring that point is not overpulled. It is this ability to hold measurements that necessitated the heavy construction of the fixtures. Later developments created universal jig fixtures with "head" sets that could be leased that fit the specific vehicles without the cost of the entire fixture. Then you missed the shortcomings of the new computer systems. Dust in the shop can throw off lasers and temperature and other sounds affect the sonar systems. Also, it is easy to cheat with the targets. I have seen techs stach washers on a target to simulate a measuerement point to be off and then remove the washers on the "repaired" printout making it look like he had made a pull on the vehicle when he had not. Because of the documentation, he was paid because he had the "repair" documented. Mercedes requires factory authorized bodyshops to use the bench system. Since with a jig system the fixtures either fit or they don't fit, a photograph is all you need to see if a pin fits a hole and if it doesn't fit, you can see by how much and how far without any numerical calculation. Finally, using the "undamaged" side of a car as a reference is not accurate as energy can travel through a unibody and effect the entire car. Anyone who ever did a "T-Bone" hit knows how a car can "bannana" in shape or hit in the front and the trunk lid does not fit.


Posted 2008-09-16 22:31:48.0
Measure systems are more widely available, it is good news, but our rates and "Progressive" disease hurt the acquisition of such good beauty. Technology goes up and our industry goes down.

Collision Repair

About the Author

Kevin Mehok