The throw (or eccentric offset) [:
Centripetal force is a force that makes a body follows a curved path: it is
always directed orthogonal to the velocity of the body, toward the
instantaneous centre of curvature of the path
Stroke Diameter (Offset)
All other parameters being equal, a
machine featuring a large stroke (or offset) will create more centripetal force
than a machine featuring a small stroke, because centripetal force is the
primary element that causes the backing plate to rotate. The higher centripetal
force will add a higher shearing force than what other machines would transfer
to the pad. You need to slow it down a little and ease off applied pressure
Why is a large diameter stroke or orbit beneficial?
[To
better understand why a large stroke machine can deliver better and faster
polishing results, imagine hand sanding a panel of wood with a typical sanding
block & paper using very short 1mm back and forth strokes. Although sanding
would be concentrated and exact, most of the sanding debris would remain
positioned between the sandpaper and wood panel. Rapid clogging of the
sandpaper would likely occur, effectively limiting cutting power and finishing
potential.
However, if the length of each sanding stroke was increased (within
a similar time frame), the sandpaper would move along at a more rapid pace. The
increased speed of motion would assist in loosening any stuck-on debris from
the sandpaper, all the while helping to eliminate sanding debris residing
between the paper and wood surface. The exact same principles of extending the
stroke apply when using the LHR21ES, except its motion is rotational (not
linear), and we use buffing liquids (not sandpaper) to accomplish our work.
High speed + lots of motion = very fast polishing.
A majority of the buffing liquids available today utilize
abrasive particles that are engineered to assist in polishing the surfaces
we're working on. To work efficiently, these particles must occasionally shift
and tumble in order to keep them free of debris, minimize clumping of the
abrasives, and slow contamination of the buffing pad. The LHR21ES's
large-diameter stroke (21 mm) and high-speed capability (4,200 RPM) combine to
deliver unrivaled performance in this regard, utterly stomping the performance
mustered by other competitor's machines] – Kevin
Brown
Therefore, if you use a machine with a
large stroke size, you should generally see an increase in random pad rotation
versus an identical machine featuring a short stroke. If the orbit offset is
doubled, the speed of the backing plate is also doubled; however, the abrasive
ability is increased by more than double.
If you are a professional detailer you
will probably have both machines, but the Flex® 3401 (the rotation rate is 1/10
of the orbit rate) is definitely going to speed up the correction process.
(OEM) production line paint finishing and correction use a large eccentric
offset machines. Flex® Dual Action Machine Polishers are designed and built in
Germany, they are the preferred choice of Porsche Body Shops and RUF
Automobiles GmbH.
Speed and efficiency is the strong point
of the forced rotation of the Flex®. It’s really easy to handle, and the power
of the Flex with curved vertical panels actually resulted in a substantial
decrease in detailing time since the pad never stopped spinning. A slightly
stiffer baking plate along with Menzerna polishes, Lake County Hybrid pads are
an ideal polish/pad combination
The Rupes Bigfoot has a large 15 or 21mm
eccentric offset and has an indirect drive, making it virtually impossible to
cause a strikethrough on the paint [2]. The Flex 3401 has a standard 8mm
eccentric offset and uses a direct drive motor, allowing the user to apply more
downward pressure.
Flat pads, on a long stroke orbital
polisher will create localized surface hot spots, nor do they exert an even
pressure A pad with a waffle type surface allow constant contact over the whole
pad surface, promote an even pad temperature and allows backing plate rotation
at lower machine speeds
When polishing you shouldn't have to
apply heavy pressure to the point where the Rupes would stall and the long
throw would allow the polishes and compounds to work better as it abrades the
surface. All that is required with either machine is that the pressure is sufficient
to compress the pad 50% < but not flatten it
Suggestion: use Optimum foam/microfiber
pads to reduce heat transfer
Notes
1.
Speed, kinetic energy (friction heat), applied pressure, foam pad actual
surface contact area, pad and polish / compound grit number (abrasive ability)
amount of surface lubrication available, area being polished, and material
(paint, especially paint edges, plastic, metal, etc.) heat conductivity of the
material being polished
The
above will, given the right circumstances, 'friction burn' (strikethrough) a
paint surface wither it be a rotary or an orbital polisher; the operative word
here is excess kinetic energy (friction heat)
2.
As opposed to paint burn, the cause of which is the localized and excessive use
of kinetic energy
Current Information
To be of real practical use, a subject like automotive detailing requires a great deal of research, and updating as new products become available. The advent of materials like detailing clay, micro fibre technologies and finely milled micro diminishing abrasives, suitable for ceramic nanotechnology paints are examples of why it’s so important to monitor the industries new products, chemical technologies and ideas that are constantly being introduced, as are the techniques for applying them, hence all of the in-depth articles will be up-dated and revised on a regular basis
Always be willing to learn; because the more you learn, the more you’ll realize what you don’t know. You should never stop learning, and your quest for information should be part of your everyday process. It is said that knowledge is power, with the caveat that it includes access to a reliable information sources. I would like to think that these articles become an asset to anyone who is new to detailing and to professional’s alike, as well as industry experts who seek to advance their knowledge.
I hope these articles are informative. They are based on the current status of technical development as well as my experience with the products.By having some understanding of the ‘What’ and ‘Why’ as well as the ‘How’ along with a little science to help you understand how the chemicals we use react, you can achieve the results you desire.
I would appreciate it if you would share these articles as it helps other detailers further their knowledge.
As always if you have questions, I’ll do my best to answer; bear in mind the only stupid questions is the one that was unasked. Questions and/ or constructive comments are always appreciated
Copyright © 2012 TOGWT® (Established 1980) all rights reserved
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