Efficiency of 5" pads versus 5 1/2" pads

[allenk4]

5" pads to polish a whole car? Would take wayyyy too long, IMO. 5.5" is small enough!! LOL

This quote made me think and get out the calculator

a = pi * r2


5" pad surface area = 19.63 square inches

5 1/2" pad surface area = 23.75 square inches


So yes, the 5 1/2" pad is 21% larger, so theoretically it saves you 52 minutes on a 4 hour polishing job


The huge difference would be going from 5" to 6 1/2'; which is almost 70% larger and would reduce a 4 hour job to just 1 hour and 12 minutes.


I personally do not believe that these numbers hold up in the real world.

 

[SR99]

I personally do not believe that these numbers hold up in the real world.

Yep, I'd have to agree. Since you overlap your passes, and the overlap isn't exactly done with measured precision, it's not going to be very close to the theoretical.

Plus there are going to be panels where you can only fit a couple-few rows of passes regardless of whether 5 or 5-1/2" so in those cases there'd be no difference at all and you just have slightly more overlap with the larger pad.

Also you'd factor in the orbital throw, since that increases the effective pad sweep area to be a bit more than the physical dimensions of the pad. But the improved cutting speed of the larger throw is probably more of a factor than the effective size of the pad.

 

[Desertnate]

I would think this depends on the type of work you are trying to accomplish.

If spreading out wax, you're probably right. However, if you're trying to polish/correct the opposite might be true since the "working" forces are distributed across the larger pad vs being more concentrated on a smaller pad.

Just thinking out loud and calling on memories from my extensive High School level physics.

 

[Tato]

This is a great discussion, thanks for posting.

I agree that there are many other variables, but what don't? ... I just think it's one more (important) factor to know and consider while polishing, and input from everyone improved a lot your calculation data.

While reading I've thought a lot about the way I overlap passes (which I generally don't think a lot about). I'm always doing ~50% overlap, without considering many other factors, just because 'everyone' does it.

Sure I've gained +1 XP after reading this topic.

Thank you all,

Kind Regards.

 

[allenk4]

When you do four passes

Overlap by 50%

Go up to the edge of a door....


Does that last 2 1/2" at the edge of the door actually get 50% less polishing?

 

[SR99]

When you do four passes

Overlap by 50%

Go up to the edge of a door....


Does that last 2 1/2" at the edge of the door actually get 50% less polishing?

Yes, and if I understand what you're saying, wouldn't it be on both ends, for any large panel?

That's why on the 2 ends of the panel I try and only do minimal overlap with the adjacent pass, and about 50% overlap for the middle passes, with a longer dwell time on the end passes. But you can't avoid uneven polishing on narrow panels that are only for example 2-1/2 pad widths wide.

Generally I imagine we overpolish every panel, even the ends, since it's not like we can stop at the exact nanosecond the finest remaining swirl disappears. We go beyond that point. Not sure but it seems it should be less critical that we overpolish if using diminishing abrasives, but we're probably talking small fractions of a micron difference.

 

[allenk4]

Yes, and if I understand what you're saying, wouldn't it be on both ends, for any large panel?

That's why on the 2 ends of the panel I try and only do minimal overlap with the adjacent pass, and about 50% overlap for the middle passes, with a longer dwell time on the end passes. But you can't avoid uneven polishing on narrow panels that are only for example 2-1/2 pad widths wide.

Generally I imagine we overpolish every panel, even the ends, since it's not like we can stop at the exact nanosecond the finest remaining swirl disappears. We go beyond that point. Not sure but it seems it should be less critical that we overpolish if using diminishing abrasives, but we're probably talking small fractions of a micron difference.

I agree...all four edges would receive 50% less polishing

 

[RaskyR1]

Kevin Brown created a nice little chart a while back for the difference pad sizes make...

 

[allenk4]

Nice Chart

Very good tool for explaining the relative differences


For anyone who wants to save it:

Right Click on it and select Save As

 

[281]

Cool chart!

 

[FUNX650]

Besides what appears to be solely the (albeit an important) difference between two different-sized pad's total available surface area, that could be used for the buffing cycle...
What else can effect a pad's efficiency?

Just a thought:
Would not the attainment of the greatest:
Net available pad surface area, during the buffing cycle, be just as an important of a factor?

If so:
How can this be attained?
Your ideas/thoughts will be most appreciated.


Bob

 

[SR99]

Since it's the abrasive particles that are doing the majority of the abrading, maybe the abrading efficiency is more about the pad's ability to act as a reservoir for fresh abrasive as it orbits/rotates?

Taking that to an extreme, would a fully primed 5" microfiber pad and Megs D300 be more efficient (i.e. finish the correction faster) than a fully primed 7" polishing pad with fine, tiny foam cells and also using D300, even though the 7" pad has nearly 100% more surface area? I would assume so but have never done that comparison.

 

[FUNX650]

Since it's the abrasive particles that are doing the majority of the abrading, maybe the abrading efficiency is more about the pad's ability to act as a reservoir for fresh abrasive as it orbits/rotates?

Taking that to an extreme, would a fully primed 5" microfiber pad and Megs D300 be more efficient (i.e. finish the correction faster) than a fully primed 7" polishing pad with fine, tiny foam cells and also using D300, even though the 7" pad has nearly 100% more surface area? I would assume so but have never done that comparison.

What's the effective surface area of the wall thickness, of the 7" pad's tiny foam cells (pores), during the buffing cycle?

Bob

 

[allenk4]

What is your definition of: "Net available pad surface area, during the buffing cycle"

 

[FUNX650]

What is your definition of: "Net available pad surface area, during the buffing cycle"

Glad you asked!

Basically it's:
"The totaled-amount, of all the wall thicknesses of a foam pad's pores/cells;
and any stressors, they may incur, during a buffing cycle".

-Hope you are able to implement this definition towards answering the questions contained in Post#11.

Bob

 

[allenk4]

Glad you asked!

Basically it's:
"The totaled-amount, of all the wall thicknesses of a foam pad's pores/cells;
and any stressors, they may incur, during a buffing cycle".

-Hope you are able to implement this definition towards answering the questions contained in Post#11.

Bob

Assuming all things ceteris paribus, between the different sized pads.

 

[FUNX650]

Assuming all things ceteris paribus, between the different sized pads.

Sure...
But here's the deal:

-As long as any objections, such as an Humean-accounting of causation:

TO WIT:
"An object precedent and contiguous to another, and where all the objects resembling the former are placed in like relations of precedency and contiguity to those objects that resemble the latter".

And/or:
The existence of any other tendencies...

-Is not denied.


Bob

 

[allenk4]

Sure...
But here's the deal:

-As long as any objections, such as an Humean-accounting of causation:

TO WIT:
"An object precedent and contiguous to another, and where all the objects resembling the former are placed in like relations of precedency and contiguity to those objects that resemble the latter".

And/or:
The existence of any other tendencies...

-Is not denied.


Bob

Thread Killer

 

[FUNX650]

Assuming all things ceteris paribus, between the different sized pads.

Thread Killer

:iagree:


Bob

 

[allenk4]

I was forced to use a 6 1/2" Yellow Lake Country CCS Pad last week as my Orange CCS was not getting it done and I didn't have Yellow in 5 1/2"

Made me contemplate going back to larger pads on my Flex 3401

I only had a couple of spots where I needed a smaller pad and the big pad, cut just as well and covered ground a lot faster. Pretty sure it was not 40% faster as the increased surface area would suggest, but still faster

I am ordering the LC Hybrid Wool in 6 1/2" soon