What's your techhnique with the PC (pressure and setting) ?

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imported_zenhog

New member
I'm working with my PC to do some polishing (scratch removal mostly) and have a couple of questions about technique:



1. How do you translate rotary rpm to settings on the PC? Menzerna says their IP works best at 1000-1200 rpm. I'm sure that's a rotary setting. what would the equivalent be on the PC scale?



2. How much pressure do you use? I've seen threads that talk about "really bearing down" when removing tough swirls. I've also seen advice to put little pressure on it.



3. What really does the work on the PC - amount of rotation of the pad (spin speed) , vibration speed (the setting), or a combination? If I "bear down" with pressure then the pad's rotation gets slowed down. If I take most the pressure off the PC then I can really get that pad spinning. Am I reducing effectivity by taking out rotation?



4. How does the speed setting affect the "cut" ?



and lastly



5. How do you determine what setting to use? I did most of my PI3 RC and RC extra cut work on 4. Sometimes I bumped it up to 5-6 but I think the only difference it made was creating more "sling". But then again I'm still pretty new at this.



Thanks for the help.
 
Well from my experience when you really bear down it almost (or does) stop spinning...and at the very least significantly slows down. Maybe a little pressure is helpful...not much.
 
Can't speak to what does the work. Really the PC doesn't vibrate, it orbits. That is the pad moves around in an orbit similar to the way your hand would. This is how I believe the PC achieves results.



As for my tecnique. Really you don't need a lot of pressure if you've chosen the right product and the right pad. On a horizontal surface I really just let the PC do its stuff while I guide it around. On a vertical surface I just apply light pressure.
 
Depends on the swirls and the product you are using. If I am using DACP and a cutting pad to remove heavy oxidation and deep scratches and swirls, I really bear down on it. DACP has diminishing abrasives, so you have to work it to break the abrasives down. As I make more and more passes, I ease up on the pressure until I am just guiding the tool around.



If I am using SMR to finish up, or a paint cleaner with a polishing pad, I'll use moderate to light pressure and ease up to the weight of the PC again to finish.
 
1) I'm pretty sure you can't really compare rotary RPM to random orbit OPM because RO machines don't produce that much heat.



2) I don't use pressure...



3) .....which allows the pad to spin a bit. I don't know how much this helps, if at all, but it's why the PC is called a "dual action" polisher, and the PC manual says not to. You'll find people who do and don't use pressure and both camps seem to end up happy in the end.... :nixweiss



4/5) Increasing speed increases the number of times the product rubs the paint, so I don't think it should increase or decrease cut (which AFAIK is a function of the pad and polish anyway) but the faster you run it the more work you're doing. I've been stopping at about 4.5-5 because that feels right for me, and if that means I have to work it longer than I would if I'd run it at 6, so be it.



Lots of different techniques out there... if you haven't checked them out already, I have links to 2 PC usage articles near the bottom of the PC thread in my signature.
 
I usually don't apply that much pressure, but I am not entirely satisfied with my results given that I have put a LOT of work into getting the swirls out of my car, and they are still there. The next time I DACP I will probably add more pressure to see if that helps.



ALTHOUGH...I used to apply more pressure and I did notice that things were different when I used little pressure and allowed the pad to spin...more heat in the pad when I finished, etc....so maybe I won't bear down more... :rolleyes:



Either way, I had always kept the PC setting around 4-5, and I just started experimenting with 6. 6 is good and it does seem to work a bit faster and better, but it also makes more of a mess. As you work a little dry polish always accumulates at the top of the pad and that 5-6 jump is the cutoff for when it starts dusting all over the car which is incredibly annoying.
 
endus said:
I usually don't apply that much pressure, but I am not entirely satisfied with my results given that I have put a LOT of work into getting the swirls out of my car, and they are still there. The next time I DACP I will probably add more pressure to see if that helps.
Click to expand...



Maybe then the issue isn't that you're tecnique isn't right, but you need something stronger than DACP?
 
The only thing I need to do is reduce the size of the area I am working. The DACP got a lot of swirls out, just not all of them. I think if I reduce my work area a little more it'll be perfect.
 
Maybe that's the key. How big is the area you are working at one time? I usually divide the hood into 3 areas if it is a car, and 4 if it is a large car or small SUV. It could be that you are not working the product effective by trying to do too much of an area at once.
 
I was doing 3 on my Maxima but I need at least 4...maybe more depending on how it's easiest to divide it up. I'm also just going to bite the bullet and use 6 on the PC. I've never bothered masking before but I'm going to do that and maybe even just toss some towels over the windows in case it dusts (usually does on 6).
 
Thanks for all the great input guys!



Area - almost every instruction guide I've seen says do an area "2 square feet". Well, that's about 16" x 16". Small area huh! But I think that's a good guide. That means a hood of a car should take some 4 - 6 areas to get done. At least!



Regarding speed - I agree, you get more work done at higher speeds and you also get more mess. But maybe not... 3M says use their RC at around 1200 rpm. Menzerna says the same or slower. Most instruction guides I've seen say the rotaries START at around 1300 - so these mfg'rs are telling us to use what turns out to be a very slow speed. How to reconcile that?



Regarding pressure - I also noticed that I get a different action if I barely put any pressure on - in other words the pad spins like a son-of-a-gun. Does that help or maybe add swirl marks? I'll leave it up to you guys who use these things a lot to comment on that.



One last note - regarding changing speed while working. I suspect that the engineers at PC have NEVER used one of these. Adjusting the speed while using it - unless I'm holding it wrong - is one of the most awkward things I do in a day. What gives with that? Why not have the speed adjustment near the place where you naturally rest your finger? sheesh. PC are you watching???



Regarding speed/pressure as it relates to a product - have any of you found that a certain product works significantly better at one speed/pressure combination and not at another? If so, then there's a variable in the equation that needs to be understood better. Maybe the Pi3RC I'm using is perfect for what I need it to do, I'm just using the machine incorrectly.



Ok, back to the experts. Thanks again for your input.
 
I've found I have to apply some pressure (often/usually enough to cause that "behavioral change" under discussion) to get out serious flaws, even when using aggressive compounds and wool pads. And I usually start at 3 and work up to 6. As for PC engineers trying to adjust the speed while working it, remember that it was really designed as a SANDER.



There definitely ARE two schools of thought on this, and that's just what *I* do (after nearly 20 years of using RO's for this, BTW). When I apply very little pressure ("let the machine/pad/polish do all the work") it NEVER gets out anything except the finest swirls. Fine for final passes, but not very aggressive at all.



FWIW, I've noticed that the Cyclo (generally considered a more aggressive RO than the PC, despite its fixed, lower speed) doesn't change behavior NEARLY as much/dramatically as the PC does when you bear down on it.
 
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