4" pads with rotary???

**evo77** · 03-21-2007, 12:57 PM

I`ve seen some online detail supply stores state on certain 4" pads that the speed should not exceed 1000 rpms. Why is this? And is this for all 4" pads?

Is there any extra care needed when using these smaller pads with a rotary when polishing an entire vehicle?

**BobD** · 03-21-2007, 01:10 PM

Originally Posted by evo77

I`ve seen some online detail supply stores state on certain 4" pads that the speed should not exceed 1000 rpms. Why is this? And is this for all 4" pads?

Is there any extra care needed when using these smaller pads with a rotary when polishing an entire vehicle?

Because they have such a small surface area they heat up very fast and can cause heat damage much faster than a larger pad. You should be VERY cautious when using them with a rotary.

**coupe** · 03-21-2007, 01:19 PM

Becuase of that i only use them on the PC, even then caution needs to be taken.

**evo77** · 03-21-2007, 01:51 PM

Would stepping up to a 5" pad be better? I have a Dodge Neon and when using a 6.5" Megs pad I feel that its too big IMO. I`d rather have a smaller pad to be able to manuveur easier.

**coupe** · 03-21-2007, 01:58 PM

Originally Posted by evo77

Would stepping up to a 5" pad be better? I have a Dodge Neon and when using a 6.5" Megs pad I feel that its too big IMO. I`d rather have a smaller pad to be able to manuveur easier.

I personaly dont use anything bigger than 6" pads on the PC.

**BobD** · 03-21-2007, 02:04 PM

Originally Posted by evo77

Would stepping up to a 5" pad be better? I have a Dodge Neon and when using a 6.5" Megs pad I feel that its too big IMO. I`d rather have a smaller pad to be able to manuveur easier.

Personally I don`t go lower than 6.5" pads on a rotary but I know there are people out there that do and have mastered it with smaller pads.

**porta** · 03-21-2007, 03:12 PM

Originally Posted by evo77

Would stepping up to a 5" pad be better? I have a Dodge Neon and when using a 6.5" Megs pad I feel that its too big IMO. I`d rather have a smaller pad to be able to manuveur easier.

Go for the 5,25" LC CSS pads from danase.

**Accumulator** · 03-21-2007, 05:45 PM

I use 4" pads on the rotaries pretty often (well, often for me), but then I`m always *so* cautious with it anyhow...

**evo77** · 03-21-2007, 08:42 PM

Define cautious. Quicker pad movement? Lower speeds? Less time working an area?

**imported_Ivan Rajic** · 03-21-2007, 08:47 PM

Originally Posted by evo77

Define cautious. Quicker pad movement? Lower speeds? Less time working an area?

d) all of the above

**wannafbody** · 03-21-2007, 11:28 PM

A 6 or 6.5 inch pad is best for the roatary because they are thicker than many smaller pads. This allows more flex over curves.

**imported_Totoland Mach** · 03-22-2007, 06:23 AM

Be careful.....be very careful. I used a small 3" pad on an air powered rotary to try to correct some serious scratches between the door handle and window trim on a BMW 745Li and didn`t realize how hot small diameter pads got. Needless to say, I burned a dime sized area in the paint and it was in the most noticeable places on the car. Every time you grabbed the driver door to open, there was the spot.

The small pads can generate heat super quickly with a rotary (air or electric).

Totoland Mach

**Todd@RUPES** · 03-22-2007, 07:44 AM

Intrestingly enough, a smaller pad is also safer for certain reasons, the main reason is that the biggest factor in working power (friction) is the speed at which the pad is rotating against the surface. A bigger pad travels a further distance per rotation vs. a smaller pad. So, while a 4, 6.5, and 8 inch pad may all be traveling at 1000 rpm, the effective speed they are traveling is much different. Infact, an 8 inch pad is moving twice as fast on the outside as a 4 inch pad. If we use the an equal equation of pressure x speed to reach a solution of how much work is being done on the surface of the paint, then the equation would look like P x S = W. With an eight inch pad, the equation would look like P X (2S)= W. As you can see, you are increasing not only the diameter you are working, but also working at a faster rate against the paint.

That is, an 8 inch pad allows for much more work to be done in a less amount time at the same RPM and pressure. Now, for thermodynamics.... An eight inch pad will dissipate more heat then a 4 inch pad by a number squared. If a 4 inch pad is able to dissipate 10 units of heat effectively, an eight inch pad can dissipate 100 units of heat effectively. Which means, while also being less effective, a 4 inch pad can also be more dangerous becasue heat is an unwanted by product of friction. Your pad manufactorer suggests no more then 1000 rpms to keep the surface cool, yet at 1000 rpm, you are producing much less working force then an 8 inch pad 500-800 rpms depending on the pressure.

As you can see, by going to a smaller pad you are reducing the effectiveness of paint removal while increasing the risk of burning the paint.

**imported_iceberg** · 03-22-2007, 11:37 AM

TH0001, thanks for the best explanation I`ve read on this subject.

**Junebug** · 03-22-2007, 12:05 PM

Currently, I`m using 6.5" LC pads on my Makita. I will be buying 8" Edge pads as soon as I can. I think the wider pad will be more stable, and I`ll run the buffer at a lower speed till I get the feel for it. And, I will be getting wool pads - thanks to David F., I`ve decided to give them a try. Side note, this coming Sunday, I`m detailing a boat with wool pads designed for gelcoat, can`t wait to report on that.