Hard paint, soft paint questions

[Saintlysins]

Great description of the rotation to pressure ratio �€œACCUMULATOR�€ & �€œNEOFATE�€, and now I understand why you�€™d prescribe the smaller pad. This really helped me realize that there�€™s two ways to tackle the same job. I�€™ll describe the way I was �€˜groomed�€™ to use a PC (or any multi-action system), and you�€™ll see why I couldn�€™t understand the suggestion.

I really hope this does not come across as anything more than my opinion �€ and by no means a challenge or to say you procedure is wrong.

I have always applied enough pressure to allow the pad to rotate and vibrate simultaneously. When I want more cut I�€™ll use a more aggressive pad and aggressive cut compound to achieve desired results. Since I switched over from the 40 lb Black & Decker grinder converted to buffer in the early 80�€™s �€ (geeesh, am I old or what?) �€ I did this with the mindset that weight and pressure have been replaced with the science of �€˜cut-and-polish technology�€™. So I�€™m programmed to never use pressure to do the work of the cutting and/or polishing. When I see new guys in the shop pressing hard enough to stop the rotation while looking for better results, I�€™ll tell them to swap pads and/or compound. My mindset is to let the products do the work, not muscle. Even if it becomes a 4 or 5 step rub to get the results desired. (Keeps muscle fatigue and strain down too �€ especially over the whole week.)

I been schooled that too much pressure also distorts the pad surface too much for its designed effectiveness. I would �€˜assume�€™ (sorry, I hate that word too), that this is when the pressure from a distorted pad and the concentrated heat build-up will remove too much finish than necessary at one time and the cause for chewing right through clear-coats.

Now that you understand why I couldn�€™t comprehend the pad size prescription, I hope to make you laugh with this part �€ Since all size pads come in the same cut/finish, I always thought the smaller pads are for tighter areas or extreme compound curves and corners.

Again �€ not to discount anyone�€™s methods �€ this is only my opinion and the way I was trained.

�€œKAIYENS�€ you sure got your monies worth on this thread. Hope it�€™s not too confusing and you find what works best for you.

[Accumulator]

saintlysins- Ah, that does help explain where you`re coming from on this (and you and I are, I suspect, of a, uhm, similar vintage ).



I started with the rotary, so I was always against using pressure too. When I got the Cyclo (mid-`80s) I learned that (with the more gentle tool) I needed to apply pressure, and I never had any problems from doing so.



When I got a PC I found that it simply didn`t do much of anything without pressure, but that it was a mighty fine line between enough (do do correction) and too much (resulting in the "jiggling"). Once I switched to the 4" pads, problem solved!



I suspect that B & D grinder is more powerful than the Cyclo/PC and can indeed "let the pad and product do the work", which is a theory I`ve found unworkable in practice with everything except a rotary...well, everything except the PC with those 4" pads IMO it`s a matter of what the machine can accomplish and a grinder is gonna have more oomph than a finish sander.

[Saintlysins]

I just re-read what I wrote and realize you could think I�€™m still using a converted grinder. I should have been more explicit and said:

�€œSince I switched over from the 40 lb Black & Decker grinder converted to buffer in the early 80�€™s to a PC ... blah, blah, blah�€

I didn�€™t mean to imply I�€™m STILL using an old B & D conversion. I am still using PC�€™s and some weird Japanese brand Dual Action which has a little more umph than the PC�€™s.

Sorry for the confusion.

[Neofate]

Here is my take on it.



Saintly -- I think your method and practice is dead on. It is the safe practice and proper practice of using a random orbital, the pads, and the polish.



You don`t apply too much pressure, if it stops rotating you change pads to allow the pad to cut more agressively at less pressure.



That is smart.



I think we are ultimately on the same page.



You see,.. regardless -- There is only so much pressure you can apply to a RO,.. PC/UDM type. Regardless of pad .. it will stop its rotation at a relatively minor amount of force.



We are suggesting a small pad for more cutting power with the pressure. This pad is acutally cutting more extreme, because it is allowing a bit more pressure due to smaller surface area. It is essentially giving the motor less to turn, thus a bit more power and able to handle a little more pressure.



I think your way is understood by us both,.. and is the best way to go about things if it can be accomplished in that manner. Keep working up from least agressive to most agressive till the job gets done.



However, if I find say, a 5.5" Orange with a fairly agresssive polish is taking 2-3 passes to get the defects out,.. I will move to a 4" pad, orange, with same polish. Which ultimately should cut it down to 1 pass. (Hopefully). Time saving effort, and no one wants to spend more time than is necessary. The old work smarter not harder.



In my opinion, I would rather use a little more ft-lb of pressure on the first pass (non-damaging of course) than to make 2-3, or 4 passes of light pressure.



That doesn`t mean this is the only way,.. or the preferred way. But I think after you get used to the machine and experiment, you can safely jump directly to a more agressive approach without any inherent danger.



I wouldn`t suggest and intense polish with an orange 4" pad on a Brand new Honda to a first timer.



This isn`t about right and wrong either, just suggestions on what works. I, for one, do want any and all ideas on how to get the job done more effectively. Which results in better outcome and faster overall time to achieve such.

[Saintlysins]

Seems we three (Sins, Accu & Neo) agree we�€™re getting to the same results, just using different methods we are most familiar with. Seems �€œKAIYENS�€ got good info out of all of us on this thread!

Thanks!

[Accumulator]

Saintlysins- Hey, if somebody gets better results with the PC using milder approaches than I have to employ, more power to them :xyxthumbs No reason to fix what isn`t broken

The back plate on the UDM is 5 1/4" -- Is that the same as PC?



And would I need to order a smaller backing plate for the 4" pad? Or just put the pad on the back plate , just have a slightly larger uncovered area of the backing plate -- I don`t see where that would really hurt anything, not like I`m gonna push through the pad and back back plate hit the paint.

The PC plates are generally 5" or 6" as they were designed to fit the sandpaper sheets almost exactly (aftermarket plates are generally a little smaller to give a margin of safely with foam pads).



I would *NOT* use a pad that`s smaller than the plate. I don`t mind having them the same size (though many advise, very emphatically, against that), but that`s as close as I`d cut it.



IIRC my smaller plate for the 4" pads is about 3.75". Places like Top of the Line Auto Detailing Supplies and Classic Motoring Accessories - Car Buffers, Car Waxes, Car Polishes, Auto Detailing Supplies, Car Covers, Car Accessories oughta have `em, I forget where I bought mine.