6.5" Pads w/ 5" BP

[D&D Auto Detailing]

Ive been thinking about this and Im not so sure 6.5" pads with a 5" backing plate is very efficient. I mean you've got a whole 1.5" around the BP where the pad isnt seeing the same amount of pressure. Sure this is one of the reasons you need to overlap your passes, but wouldnt a 6" BP with 6.5" pads be a lot more efficient?

[FMINUS]

Ive asked this question before and the response I got was that it didnt matter. But in my experience, I feel the same way as you do.

Also the extra padding seems to curve up when pressure is applied, taking it off the surface of the paint... The only benefit I see is extra foam to protect the backing plate to hit against the paint.

[D&D Auto Detailing]

Exactly, I agree 100%. The edges do curve up and the only benefit I see is extra protection. Dare I say I dont need a whole 1.5". Half an inch is plenty for an experienced user IMO. Im going to order a 6" BP so I can actually use my 6.5" pad to its fullest. Otherwise I might as well just be using the 5.5" pads.

[makdaddy626]

My thoughts (keep in mind I'm pretty new to using the PC)...

You don't have 1.5" of protection, you have .75" inches assuming your pad is centered a mere 1/2 inch more than the .5 you indicated you wanted for safety (.75 on either side of the plate).

Also, it seems like the "extra would provide some give for panels that were bowed inward (is that concave or convex?) or for any irregularity in the flatness of the panel.

[D&D Auto Detailing]

If the panel isnt completely flat then Ill switch to my 4 or even 3.5" pad. I never only use 6.5" pads for a car. So that isnt a problem. I havent measured, but I doubt I center my pads more then 3mm off.

[makdaddy626]

If the pads are centered (which I don't doubt they are) they you only have 3/4" overhang, right? That just doesn't sound like that much to me.

[ZoranC]

There is a limit how much of an extra foam will transfer the pressure. That limit depends on foam thickness and density, and even design of backing plate, among other factors. Everything else does practically nothing for you(you can easily see that if you take a look at surface of pad after using it with product that will leave "footprint" on the pad). I consider that dead weight counter-productive as it means there is more weight in the pad than what is neccessary which increases load on motor, decreases it's lifetime, decreases efficiency (torque and temperature) and increases vibrations (once again increasing load and decreasing lifetime).

[D&D Auto Detailing]

Originally Posted by ZoranC

There is a limit how much of an extra foam will transfer the pressure. That limit depends on foam thickness and density, and even design of backing plate, among other factors. Everything else does practically nothing for you(you can easily see that if you take a look at surface of pad after using it with product that will leave "footprint" on the pad). I consider that dead weight counter-productive as it means there is more weight in the pad than what is neccessary which increases load on motor, decreases it's lifetime, decreases efficiency (torque and temperature) and increases vibrations (once again increasing load and decreasing lifetime).

So what exactly are you saying? Obviously the extra unused foam is the dead weight right? So do you step down to 5.5" pad, or step up to 6" BP?

[ZoranC]

Originally Posted by D&D Auto Detailing

So what exactly are you saying? Obviously the extra unused foam is the dead weight right? So do you step down to 5.5" pad, or step up to 6" BP?

I am saying that you need to match size depending on what you are after and what you can do while taking all this into account. Let's say you are using PC and feel bigger pad surface is what you want to use at the moment. You step up backing plate, otherwise you will not have any benefit from bigger pad you want and you will have drawbacks. Later you want to use tool that you do not have bigger than 5" bp for (or to be precise 4.75"). You will not get any benefit IMHO by sticking with 6.5" pads, but you will get drawbacks. You would be better off by stepping down pad to 5.5" or even to 5".

[D&D Auto Detailing]

Alright, thanks.