Factors that can cause a pad to stop rotating on a DA Polisher
Below are a list of factors that can stop pad rotation tools like the Porter Cable, Meguiar's, Griot's and Shurhold DA Polishers. This isn't necessarily a bad thing, just a characteristic that also represents how and why these tools are so safe to use especially for people new to machine polishing.
The factors listed below can stop pad rotation and instead what you'll experience and see is a pad that more or less only vibrates or jiggles against the paint instead of rotates.
Pad rotation isn't important if you're applying a finishing wax or paint sealant to a finish in excellent condition but if you're trying to remove any type of below surface defect like,
- Swirls
- Scratches
- Water Spots
- Oxidation
- Etchings or stains
- Sanding marks
Then to be most effective you need the pad on these types of tool to be rotating under firm pressure.
- Too little pressure - There's a quirky thing about these tools that if you hold the pad just right against the paint as though barely touching it the pad won't rotate like it does under pressure but more or less just flutter and even rotate backwards or counter-clockwise.
- Too much pressure - If you apply too much pressure you can stop the pad from spinning, this is the safety characteristic that Newbies love and experience people forget about after they master the tool and then complain because the pad stops spinning.
- Uneven pressure against pad - If you don't hold the pad flat to the surface, that is you hold the body of the tool in a way that pressure is greater to just an edge or side of the face of the pad you can easily stop the pad from spinning. This is more noticeable with larger pads like 6.5" and 7" pads as the larger the diameter the pad the more leverage the pad has over the spindler/drive mechanism.
- Raised body line - If you're buffing on a raised body line there will be more pressure to smaller area of the face of the pad and this can be enough to stop or slow down the rotation of the pad.
- Convex or Concave shaped body panel - Like a raised body line, if you're working on a convex or concave shaped body panel you can have more pressure to the outer edges of the pad or the inner portion of the pad and this can stop the pad from rotating or slow pad rotation down.
- Too large a pad - When buffing with larger pads the larger diameter of the pad give the pad leverage over the spindle and this can stop pad rotating or slow pad rotation down.
- Wet or saturated pad - When a pad becomes wet or saturated with product the combination of foam and liquid act to absorb and dissipate the energy coming out of the tool and this can stop or slow down the rotation of a pad.
See this article for more information on how the drive mechanism for these tools works....
The Free Floating Spindle Bearing Assembly - The Story Behind The Story... The Spindle 
Watch the below TV show starting at the
10:30 mark and I will show you not only why the PC style tools are so safe but how too much pressure will stop the pad from rotating. (against my hand
)
What's in Autogeek's Garage - Episode 3 - Season 2
Linear Mode
