heavy correction: pressure vs. rotation speed

**Matt@Revive** · 05-13-2015, 11:26 AM

i'm working on a BMW M3 with really hard paint. i am using a Rupes 15 with Meguairs MF cutting pads. when doing test spots i got less them great results using M105, FG400 and D300. my test spots were done using speed 5-5.5, very light pressure and slow arm speed. after 5-6 section passes there were still a lot of swirls. i happen to dig out a sample bottle of the new FG300 and it cut a bit better, but still took 2 aplications at 5 section passes.

my question is, when working with harder paints is machine speed enough, or should downward force be applied at the cost of rotational speed?

**fly07sti** · 05-13-2015, 01:59 PM

With what you're using, I'd try to add a little downward pressure. I personally have the 15 and it doesn't like too much pressure or it won't spin. I also know Meg's recommends you don't run your polisher over something like 3,800 opm's because it overheats the disc. Do you have any Xtra cut MF discs? Do you have a more aggressive compound? I would suggest trying either of the later or both. Use moderate pressure (about 10lbs) and slooooow arm movement. Now if you have a Flex or rotary and some wool, that will speed up the cutting significantly. Are you trying to one step this or two?

**Calendyr** · 05-13-2015, 03:37 PM

Rupes polishers work better at lower speed. Try speed 4 and apply more pressure. Microfiber pads and M105 is a pretty aggressive combo, there is no reason you should not be able to correct that paint. Just take your time. Make sure the pad is spinning. If you have not made a mark on the backplate yet with a sharpie, now is the time to do it. If the pad stops spinning your are not gonna get any results.

**d33p** · 05-13-2015, 04:17 PM

Put up some pics, we aren't mind readers. How do you know it's hard paint? For all we know you are putting in more haze with that aggressive combo.

**Matt@Revive** · 05-13-2015, 04:44 PM

this is a 2 step correction, i attempted to polish with just pf2500 and it took out all of the fine swirls and left too many deep swirls behind.

d33p - i have been trying to take pictures as i go, but the paint is a metalic red with fine red flake. the camera doesn't capture the defects well. the paint is hazed after my compounding (as expected), but the defects left behind ar uniform with the defect on the uncorrected portion of the paint.

**Billy Baldone** · 05-13-2015, 04:51 PM

Every BMW I have done is hard. I have had great luck with fG400 and my Flex. Both orange and in some cases yellow pads were used

**d33p** · 05-13-2015, 05:00 PM

You will need the proper light reflection in order to capture in on camera. Sunlight will usually show every defect.

Billy- Not every bmw paint is hard.