Is there a point to 6.5 inch cutting pads?

R

Rez90

New member
So most of the kits that come with polishers, polishes, and pads typically use 6.5 inch pads.



but i read that if you want to do any kind of correction that smaller pads are recommended.



aside from jeweling and/or applying wax...is there any point to larger LC cutting pads regarding correction? or anything for that matter?



Thanks.
 
I have no problem getting results out of a 6.5" on a rotary.. DA is another story. You probably wont make any amazing results with something that big
 
gmblack3a said:
I use the 6.5" classic flat LCs from properautocare.com all the time via the KBM.
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desertdetail said:
Ive corrected SERIOUS flaws with 6.5 inch lc pads on my 7424xp, guess its user dependent.
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You guys (including Kevin, with whom I've discussed this) who get good results with the larger pads via PC just *kill* me! On the GMC's hard clear I got nowhere via PC, though the same pads work super via Flex. It was an older model PC, but still....
 
Accumulator said:
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You guys (including Kevin, with whom I've discussed this) who get good results with the larger pads via PC just *kill* me! On the GMC's hard clear I got nowhere via PC, though the same pads work super via Flex. It was an older model PC, but still....
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What size backing plate are you using?



A six inch backing plate will make a noticeable improvement in cutting action vs. a smaller backing plate.



Think of the pad like a sponge that tries to absorb all of the orbital polishing action. The larger the pad, the more sponge there is (the more the action is absorbed). Using a larger backing plate allows more of the pad to be compressed equally, transferring more of the orbital motion through the pad.



A larger pad does have some advantages when used efficiently. One, the surface area is increased, so more abrasives can contact the paint (at a given time) increasing the total cut. Second, the larger pad is going to have a higher velocity at the outer edge, increasing friction. Of course the downfall of the PC is well documented: It doesn't have enough power to fight the physics of a larger pad. Current random orbital DA's tend to get bogged down by larger pads to the point that they often cut less then a smaller pad, despite theoretical advantages.



This problem is compounded by using too small of a backing plate. If you have a 6.5 inch pad but only a 4.75 inch backing plate, you can only efficiently transfer the DA motion to about 60% of the pad. You are left with a foam bumper of uncompressed and inefficient foam that offers little polishing action besides what is offered by the rotation of the machine. You get the worst of both worlds. The additional drag created by the uncompressed foam and size of the pad, while only getting the effective surface area of a 5 inch pad.



When you increase the backing plate size you will find that less down force is needed and the pad may actually rotate faster then it did with a smaller backing plate.



Will a 6.5 inch pad out cut a 5.5 inch pad on a DA? Probably not, although the difference noticed could be very small. David Fermani and I recently polished out a 1970 Porsche using only DA's. The paint in some areas needed 3-4 applications. David was using smaller pads (5.5 inch) and I was using larger (6.5 inch) pads. While he probably did get more cut, the difference was negligible and no noticeable time was saved nor did any areas required fewer passes because of pad size.



To the OP.





Is there a point to 6.5 inch cutting pads?

So most of the kits that come with polishers, polishes, and pads typically use 6.5 inch pads.



but i read that if you want to do any kind of correction that smaller pads are recommended.



aside from jeweling and/or applying wax...is there any point to larger LC cutting pads regarding correction? or anything for that matter?



Thanks.
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Building on my previous statement, there is a time when larger pads are better. Let's say you are working on a car in nice condition that only needs two steps of polishing. While the 5.5 inch pads do have some additional cutting power, for this job it is not needed. In this case the 6.5 inch pads may yield faster results as you can cover more surface area of the paint in less time. If I am using a final polish on a DA, I almost always use a larger pad to cut down on my working time.



At the end of the day it will always be personal preference. Some people will like the way certain pads feel or work. I started with 6.5 inch pads on a DA, and once I switched to a larger backing plate I got much better results.
 
TH0001 said:
What size backing plate are you using?
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First off, a belated "Welcome Back!" :wavey Nice to have you back here and posting again.



OK, now, large pads via PC: Heh heh, come on, I know to match the pad/plates ;) I was using a 6" PC brand backing plate (PN 18001) with 6" pads (not 6.5" this time, thought I'd try the older/slightly smaller pads). As I mentioned, I've discussed my travails with the larger pads with everyone from Kevin to Mike Phillips and I just don't get good results, even with M105. And at the risk of sounding full of myself, I'm confident I'm doing it right and not overlooking anything (at least *now* having heard a lot of suggestions and discussed/considered the topic to death).



Given enough time, I bet the M105 *would* work, especially with SureBuff (?SP?) pads. But I get nowhere fast via PC unless I switch to the little pads. On my Yukon, multiple section passes via PC did nothing compared to *one* such pass via Flex. I even got out my other PC, switched plates, and tried *it* to see if there'd be a difference (nope).



On the Flex/rotaries I do appreciate the advantages of larger pads (heh heh, I remember explaining the size/speed correlation to my students when discussing disk drives :D), and use them whenever suitable. My PCs just don't have the oomph to overcome the friction even when I have the priming/polishing liquid quantity just right :nixweiss



For the umpteenth time I wonder if my PCs have issues, but they were the same way with 6" pads (and to a lesser extent with 5.5" ones too) even when new/freshly rebuilt.



Next time I have something to correct, I plan to try a ~6" pad via Griot's 6" RO, maybe that'll give me the kind of results you're getting.



Again, welcome back, and thanks for trying to help me get better results with the larger pads (at this point I think *every* satisfied large-pad-via-PC user has offered their advice but sheesh, still no joy :( ). Too bad it *wasn't* something as simple as my using the wrong backing plate!
 
Accumulator said:
-AND-







You guys (including Kevin, with whom I've discussed this) who get good results with the larger pads via PC just *kill* me! On the GMC's hard clear I got nowhere via PC, though the same pads work super via Flex. It was an older model PC, but still....
Click to expand...



Check my thread with a cobalt ss, gm hard clear coat corrected with 6.5 inch pads, that's not the only hard paint I've corrected. But if you find that using smaller pads to be more efficient all the power to you! I see no need for small pads, with the exception of small surface areas. Happy detailing! :)
 
it really depends on what your doing but i do love to work with the 6.5 pads an get very good results whether correcting or jeweling but than that is just me everyone is different.
 
....I will admit my experience was similar to Accumulator's. This was also using the older model 7424 which I’m sure is a contributing factor (although I know others also claimed success using this variant). I don’t doubt that with the right products/tools/methods and some more time I could have had more success with the larger pads given the reputation of the folks who say it works. However, in my case I simply found it much easier/efficient (as a weekend DIY’er) for me to switch to smaller pads. I found they provided me with more flexibility/less fuss. I’ll be pulling the trigger on a 3401 in the near future so my PC will likely be relegated to spot polishing anyhow.
 
desertdetail said:
Check my thread with a cobalt ss, gm hard clear coat corrected with 6.5 inch pads, that's not the only hard paint I've corrected....
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Heh heh, glad you mentioned that as it's a perfect example of "YMMV" :D I was working on the hood of my '04 Yukon with the same hard GM clear, and I was working on some pretty mild marring too. Otherwise, I'm usually working on Audis, which aren't exactly soft either!



Fortunately for me, the Flex 3401 solved the whole issue for me...eh, actually the rotaries solved it, but I like using the Flex better and it's almost as quick.
 
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