4" pads with rotary???
- Thread starter evo77
- Start date
Accumulator
Well-known member
I use 4" pads on the rotaries pretty often (well, often for me), but then I'm always *so* cautious with it anyhow...
imported_Ivan Rajic
New member
evo77 said:
d) all of the above
wannafbody
wannafbody
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
New member
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
The small pads can generate heat super quickly with a rotary (air or electric).
Totoland Mach
Todd@RUPES
Just a regular guy
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.
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
New member
TH0001, thanks for the best explanation I've read on this subject.
Junebug
JAFO
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.
Accumulator
Well-known member
TH0001- Yeah, thanks for the great explanation :xyxthumbs Some of that came right back as soon as I read it...funny what you forget over the years 
Yeah, just doing everything that's caution-related a little more diligently that I might otherwise. I stop and check how hot things are getting much more often, I don't just assume that things are OK. It's like using any tool, can't be "afraid" of it but you gotta respect it too. I sorta take life seriously in general, and I apply that to using the rotary
Totoland Mach-Ouch! I bet that little burn mark really bugged you! Also bet you haven't made that mistake again
evo77 said:
lecchilo said:
Yeah, just doing everything that's caution-related a little more diligently that I might otherwise. I stop and check how hot things are getting much more often, I don't just assume that things are OK. It's like using any tool, can't be "afraid" of it but you gotta respect it too. I sorta take life seriously in general, and I apply that to using the rotary
Totoland Mach-Ouch! I bet that little burn mark really bugged you! Also bet you haven't made that mistake again
Thanks guys and thanks TH0001 for the great explanation.
I will stick with my 6.5" Megs pads for now and try to get accustomed with them. I definitely don't want to increase my chances of damaging the paint using the smaller pads. And being that I haven't used a rotary quite yet, the combination of both would be highly volitale.
I will stick with my 6.5" Megs pads for now and try to get accustomed with them. I definitely don't want to increase my chances of damaging the paint using the smaller pads. And being that I haven't used a rotary quite yet, the combination of both would be highly volitale.
3Dog
New member
Totoland Mach said:
On an air rotary you need to really turn down the air flow adjustment on the unit. Our little rotaries will run 10K fully opened.