3-D measuring systems can provide the accuracy necessary to repair today's vehicles - provided that techs are trained to accurately operate them
Note: This article is the second part of a two-part series on measuring. The first article, "Measuring Basics" covered two-dimensional measuring.
Measuring systems have gone from total user-dependent designs to systems that provide increased consistency, better resolution, ease of use and 3-D capabilities. Dedicated bench systems, universal mechanical systems, mechanical laser systems and computerized measuring systems are all part of the evolution of measuring systems - an evolution inspired by one word: unibody.
Still, despite all these technologically advanced
systems, there isn't a system on the market - yet! - that can't
be misused to introduce human error. For this reason, it's a necessity
that technicians understand how to properly operate these systems.
Dedicated Bench Systems
In the late '70s, as the unitized revolution began in the United States, the need for better measuring systems became evident. Because most vehicle makers outside North America were already producing unitized vehicles and the repair industry abroad was already using measuring systems unlike those common in the United States, the introduction of the dedicated bench system in the United States was a direct result of the systems used in other countries. (Even today, the dedicated bench system is the most commonly used system in many other countries.)
Dedicated bench systems offer many advantages to the user. The "bench" generally becomes the anchoring device to the vehicle, as well as the platform where the measuring fixtures mount for structural dimensioning. The bench is then anchored to the pulling system, solving many immediate problems involving where to hold the vehicles without damaging the anchoring areas.
In some bench systems, the pulling systems are external, separate systems that can be used without the bench or integrated to the bench by mounting pulling towers or hydraulic pads to the bench. In many cases, the latter became popular due to the mobility of the bench and pulling system.
Dedicated fixtures, measuring attachments designed for one body type, were introduced in the United States with great reception, and the original versions were targeted to the newly introduced, high-volume vehicles manufactured by U.S. automakers. The fixtures were very sturdy and not only allowed for easy identification of structural damage, but were strong enough to act as welding jigs during assembly of structural components.
These "fixture sets" for most bench manufacturers were stored in large metal boxes requiring a fork lift to move and stack. As fixture sets became available for more vehicle types, storage, rental and availability became an issue for many collision shops. To address this problem, some manufacturers began to develop universal fixture bases to fit a wider range of vehicle types and only required the ends be designed for specific vehicle types. These fixture ends or tips could be shipped easier than the complete set.
Another advantage of fixtures is how they gauge the vehicle's damage by either aligning properly in a control point, reference hole, bolt or nut. And the room for judgment is very minimal, which adds to consistency.
Normally, fixtures are designed to diagnose underbody structural areas and strut tower locations (some sets have included steering-system mounts as well). But, many times, mechanical components, such as the suspension, steering and drivetrain, require removal to use - one reason other systems became popular in the early 1980s.
Today, many vehicle manufacturers still prefer the use of dedicated bench systems for repairs, maybe because vehicle manufacturers feel the consistency gained from these systems is critical to their customers satisfaction.
The setup of these systems is very basic,
and low to mid technical skills are required to mount a vehicle
on a bench. While anyone can quickly verify repairs by looking
at the location and tension of each fixture pin, repair documentation
is difficult unless you manually mark each control or reference
point as "correct" on a setup or dimension sheet.
Universal Mechanical Systems and Mechanical Laser Systems
Universal mechanical systems became popular in the United States in the early 1980s due to the number of different vehicle types and models serviced by most repair facilities. Universal refers to the ability of the measuring system to adapt to different vehicle types and different pulling systems.
There are distinct categories of universal mechanical systems. Some systems require a great deal of assembly on the user's part - using regular dimension manuals for measuring locations - while other systems require less assembly and use their own setup sheets.
This latter category is normally designed with less "setting scales," and extension pieces, cones and attachments are color or numerically coded - which generally lessens error, again increasing consistency and speed of operation. These systems also use special setup sheets designed for them. In many cases, the equipment manufacturer has physically verified the dimensions and may include notes as to their accuracy.
Universal measuring systems also introduced the third dimension of measuring - datum length - based on the zero line/plane. Before these systems, the datum line/plane (height) and centerline/plane (width) were used with one- or two-dimensional tools to identify damage, and simple "point to point" measurements were taken for length.
The zero line/plane introduced the starting point for length dimensions for 3-D measuring systems. These length dimensions are the datum length dimensions that required conversion to be used with one- or two-dimensional tools, such as tram gauges or measuring tapes. With 3-D measuring systems, however, these dimensions aren't converted.
Universal mechanical systems normally allow for multiple point measuring and usually have upper-body measuring capabilities with the use of an overhead bridge assembly. This bar can be used not only for referencing strut tower positions, but also for other points on the vehicle by using the symmetry principle (covered in "Measuring Basics").
Universal mechanical system components are typically made of aluminum or alloy materials and can be damaged if not stored or used properly. For this reason, a technician will generally lower the measuring pointers during pulling to avoid damage.
Setup is critical when using these systems. If the main measuring bridge isn't properly aligned to the vehicle in the undamaged area, the measuring accuracy is lost in the damaged areas. Also, if during pulling the vehicle mounting moves, most systems require the measuring system to be realigned to the vehicle.
Another variation of the universal mechanical measuring system is the mechanical laser system. The mechanical laser system requires the technician to install targets at control or other reference points. By aligning the laser to the vehicle, measuring can then be done to diagnose both under-body and upper-body damage. Some laser systems are used in conjunction with a universal mechanical system, and some systems also perform wheel alignments.
The laser acts as a string of light that passes through targets. Symmetrical readings also can be used during the repair process for areas not given in the dimension guide - a technique that allows for easy location of A and B pillars during pulling of a "side hit" or checking for other "side sway" damage. Instead of installing doors to check fit, most of the pulling can be done and checked by referencing the light beam. (The universal mechanical system can normally reference these same points, but it requires the movement of the transverse bar each time a point is referenced.)
If repair documentation is required for any
of these systems, the technician must manually write the before
and after readings on a dimension sheet or a specially designed
form. Validating the repair for some systems will require going
to each point and rechecking each reading, while other systems
are designed to check repairs by locating the laser beam through
multiple targets.
Computerized Systems
During the last 18 years, manufacturers have introduced to collision repairers a variety of computerized systems to aid with management and the repair process, such as job costing and tracking, estimating, paint mixing, color verification, electronic diagnostics, wheel alignment, material inventory - and vehicle measuring systems.
Computerized measuring systems have added a new dimension to the documentation aspect of the repair process. Many years ago, the wheel alignment industry benefited from equipment that produced documentation of the wheel alignment performed, and today, that same benefit can be realized by the collision repair industry.
Computerized measuring systems fall into three main categories: laser activated targeting, ultrasonic emitters and mechanical arms. All three systems identify where the damaged points should be in relationship to the location of three main control points, with these three control points establishing the vehicle's datum line/plane, centerline/plane and zero line/plane. From this, the computer determines where all other points should be located.
These systems are generally very portable and can be used with many pulling systems. The accuracy is still dependent on user setup but is much less complex than universal mechanical or laser systems.
The setup sheets for most computerized systems require the technician to mount targets, adapters or emitters to the vehicle using specially designed pieces. As with any of today's Windows programs, the help systems do all but actually mount the system to the vehicle, and video and graphic support is extensive.
Whether the system uses targets, emitters or a mechanical arm, it's important that care is taken with setup, maintenance and storage - and be careful when welding or cutting is done around these units.
In addition to documentation, accuracy and
the ability to monitor repairs during the pulling process are
benefits not to be overlooked. Reassuring customers their vehicles
have been restored to factory specifications and providing them
with documentation goes a long way in improving business.
Precision Measurement
While the responsibilities of repair haven't changed much since the early '80s, methods and equipment available to do them more precisely and efficiently have.
Today's vehicles demand a high accuracy of
repairs, and 3-D measuring systems can provide that necessary
accuracy - provided technicians are trained on their proper use,
are willing to ensure their proper use and are monitored in that
use.
Writer Tony Passwater is a long-time industry
educator and consultant who's been a collision repair facility
owner, vocational educator and I-CAR international instructor;
and has taught seminars across the United States, Korea and China.
He can be contacted at (317) 290-0611, or e-mailed at (Tony.Passwater@aeii.net).
What's Next
In the future, all computerized systems in a shop will communicate
so information can be included in an electronic vehicle file for
easy access. This will create a more efficient paperwork process
and allow managers (or even customers) to monitor the repairs
without physically verifying the repairs in the production area.
Straight Talk
A tech suggests that you shouldn't be surprised if the specs in
the books are inaccurate - and if you're stumped by them, ask
for help.
Q: What are your main challenges when it comes to measuring and straightening, and how are you trying to overcome them?
A: "Measuring points are inaccessible because of exhaust
systems, underhood components, suspension, grease- or dirt-covered
undercarriage, crushed control-point areas due to poor lifting
procedures and poor or incomplete control-point data," says
Henry Netter, an ASE Master Certified Collision/Refinish Technician
at Auto Tech Collision in Philadelphia. "[We also have] difficulty
with accessing parts for removal and with old rusty hardware that
refuses to budge (real time/profit killer). [Also, sometimes]
prior repairs aren't quite up to standards."
Q: Are shops having trouble getting paid for all the time and work that go into the measuring and straightening processes?
A: "A good estimator/shop appraiser should be able
to rationally explain repair procedures to either a customer or
an insurance adjuster. I feel the problem is that many estimators
- shop and/or insurance - don't have the actual hands-on experience
of a start-to-finish unibody repair. This, in turn, hinders the
actual repair tech to turn a profit on a job since he's allowed
'X' amount of hours based on ... what - a guess, hope, fantasy?
Then, if it takes longer - as it usually does - the tech looks
unprofessional based on an unfair standard placed upon him by
inexperienced repair writers, not doers!"
Q: How does the shop in which you work charge for this type of work?
A: "We accept prevailing rates allowed by insurance
companies."
Q: Does any particular job stand out as being difficult or as a learning experience?
A: "Two jobs stand out in my mind. The first one was a Mustang hit in the front. Nothing measured up according to specs. After hours and days of frustration, we contacted [an equipment manufacturer], and they told us the control points in the books were inaccurate and guided us to success.
"The second one was an older foreign car that just didn't
follow standard crash damage direction. According to the books,
the crash caused the towers to roll out! No way, since the front
strut towers are designed to roll in on a front-end hit. Again,
total frustration until I rechecked and found the correct specs."
Q: Do you have any advice on this type of work?
A: "My tips or suggestions are to be patient and observant. Nothing beats experience to get you through the tough ones.
"Don't always trust the specifications in those books. If it
doesn't seem right, step back, take a deepbreath and try again. And don't be afraid to ask for help if you're stumped. It really helped in my instances."