A rotary polisher usually has 5/8-inch (14mm) diameter shaft / 11 UNC. An orbital polisher has a 5/16-inch (8mm) female thread.
The type of backing plate is even more important than most detailer’s realize, as an incorrect choice can cause overheating, contribute to swirls, compromise a pad, or add to its durability or help it to stay cooler
The backing plate directly transfers the kinetic friction (energy) of the machine to the paint surface via the pad. The foam pad will absorb the amount of orbital movement produced by the machine polisher unless sufficient pressure is applied to compress the pad (to approx 50%). Using a properly sized backing plate allows for the equal distribution of pressure across the entire face area of the pad; making it more efficient; as a backing plate only compresses the area of the pad that is directly underneath it.
A polishing system is more efficient when used with the correct sized backing plate. Using a backing plate that is the same size as the pad uses utilizes the whole surface area of the pad, you should not use an undersized backing plate. If the backing plate is too small for the pad, you reduce the effective contact surface area of the pad that is able to polish effectively, there is also a possibility that the backing plate will ‘cut’ the foam causing it to fail.
Allow a maximum of ¼-inch as a safety margin (i.e. 6.5 -inch pad- 6-inch backing plate, 5.5-inch pad -4.75-inch backing plate) this will allow the maximum pad surface contact area, and equal pad compression over the pad contact surface ensuring efficient polishing
A hard and inflexible backing plate will affect the performance of a foam pad; by making it slightly more aggressive (stiffness) and may cause swirl marks. The inflexible plastic on many backing plates has zero give and therefore will not adjust to the contoured body panels. The exception would be a plate bonded to a thick layer of dense cellular foam Lake County (LC) CCS pads.
Always use the recommended sized backing plate for the pad you are using. Do not use a backing plate that is larger than the foam or wool pad
Flexible backing plates
Lake County (LC) mfg Grip Easy™ Edge
· Easy plate removal for quick pad changes
· Prolongs life of loop material on pads
· Moulded polyurethane construction
· Hook material moulded into plate eliminates delamination
· Flexible edge
· Flexible plastic centre hub
· Ideal for transitions from flat to contoured surfaces
· Reduces risk of spot heating
· Plated steel threaded insert(5/8-inch or 14mm)
· Will not cross-thread
· Reinforced inner construction
· Steel struts moulded into centre hub for superior strength
Polish / Compound application - 5.5-inch pads (LC Moulded Urethane 5-inch baking plate) and 4-inch pads (LC Moulded Urethane 3.5-inch backing plate). A lightweight backing plate is ideal for a random orbital as offers less resistance and there more rotational speed.
Coatings / Sealant application- 6-inch pads (LC Moulded Urethane 5.5-inch baking plate)
Lake County (LC) high strength moulded urethane grip-easy edge for fast, easy pad changes, durable moulded polyurethane construction, flexible centre hub ideal for surface contours, plated steel threaded insert (5/8 -inch 11 PI female thread or a metric size 14mm) and steel reinforced inner construction
3M 125 mm (4-inch) Perfect-it III Rotary Backing Plates [are made from an impact resistant synthetic nylon plate bonded to a 25 mm thick layer of dense cellular foam, and are ideal for use with threaded rotary machine polishers such as the Makita 9227CB
The highly flexible design allows for very easy transitioning from flat to contoured surfaces, and the hook and loop backing material enables quick and easy pad changes (M14 metric & 5/8th – inch US)
Adam's Premium PC Backing Plate - by reducing the weight and increasing the flexibility this backing plate is slimmer and far more flexible than its predecessor. The new, lower profile design and improved flexibility allows the backing plate to hug those awkward curves and body lines better than ever before. The reduced weight also equals a reduction in vibration making extended use of the Porter Cable a little easier on your hands and wrist. Still perfectly balanced and constructed of high quality, durable, materials
Interface pads are placed between the backing plate and sanding disc. They increase the flexibility of a disc and help to evenly distribute machine movements and applied pressures. The right interface pad can also increase comfort while you sand. An interface pad can buffer abrupt machine movements through its cushioning action.
Lace County Constant Pressure™ Foam Pads have a layer of engineered, instant rebound foam between the pad and the backing plate. This layer acts as a cushion or shock absorber between the machine, the operator and the surface being worked on. It absorbs off-axis motion while maintaining a constant and uniform pressure on the surface; Lake County Constant Pressure™ technology allows even a neophyte detailer to achieve professional-like results.
Always use the recommended size backing plate for the size pad you are using. Use caution if using a backing plate that is larger than the foam pad or disc.
I would like to think that these articles become an asset to anyone who is new to detailing and to professionals alike, as well as industry experts who seek to advance their knowledge.
I hope the above article was informative. 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 this article as it helps other detailers further their knowledge.
Questions and/ or constructive comments are always appreciated.
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