Why is this happening?

**Grizzly** · 03-15-2010, 09:03 PM

I was using my PCXP today with a Meguiars W68DA backing plate and a Meguiars W8207 7inch Soft Buff Polishing Pad, I marked the back of my pads with a black sharpie marker to make sure the pad is actually rotating.

The PCXP was on speed 5 and the pad was rotating when no pressure was applied, but when pressure was applied the PC just started to vibrate or jiggle around and not really rotate. But when I went to speed 6 there was not a problem.

Is the pad or backing plate too large for the PCXP to handle?

Does using speed 6 dmage the backing plate or pad?

What exactly is going on here?

**JonMiles** · 03-15-2010, 09:54 PM

What happened at lower speeds?

**Grizzly** · 03-15-2010, 09:58 PM

First I tried Speed 4 and it rotated the pad under the weight of the machine but when pressure was applied the pad barely rotated, then I tried Speed 5 and when meduim pressure was applied it slightly rotated.

Then I used Speed 6 and it worked great even under pressure. The problem is I have heard the backing plate and pad can get damaged when using Speed 6.

**A4 1.8tqm** · 03-15-2010, 10:05 PM

Never used a PC myself (Flex 3401), but as far as I've read even the new PC XP can't handle 6" pads and above. Seems the 5.5" pads are the largest most users will recommend. Just my $0.02

**Grizzly** · 03-15-2010, 10:07 PM

Originally Posted by A4 1.8tqm

Never used a PC myself (Flex 3401), but as far as I've read even the new PC XP can't handle 6" pads and above. Seems the 5.5" pads are the largest most users will recommend. Just my $0.02

That does help. I am sure its not the machines fault, but rather mine.

But my Meguiars G110v1 seems to handle it better than the PCXP.

I am really confused. If I have to I will order some LC 5.5" pads, hopefully they will work with my W67DA or W68DA Meguiars backing plates.

**JonMiles** · 03-15-2010, 10:10 PM

I had a pc for a while and it seemed to get bogged a little with larger pads, but at speed 4 and 5 it was very unnoticable. I used 6.5's for a while then switched to 5.5's and never had a problem. It might be the same problem I had just to a larger extent. At low speeds it would nearly stop, fell down to like 100 opm's. I would just try some smaller pads and if it doesn't work then you might want to return it and try to get another, every once in a while you get a dud with power tools

**Grizzly** · 03-15-2010, 10:13 PM

Originally Posted by JonMiles

I had a pc for a while and it seemed to get bogged a little with larger pads, but at speed 4 and 5 it was very unnoticable. I used 6.5's for a while then switched to 5.5's and never had a problem. It might be the same problem I had just to a larger extent. At low speeds it would nearly stop, fell down to like 100 opm's. I would just try some smaller pads and if it doesn't work then you might want to return it and try to get another, every once in a while you get a dud with power tools

Yeah, I am using 7" Meguiars polishing and finishing pads so I imagine it is just getting bogged down.

**Grizzly** · 03-15-2010, 10:14 PM

Maybe I should give the stock white pad that comes with it a try, see how it works.

**A4 1.8tqm** · 03-15-2010, 10:26 PM

Those DA's have a "safety feature", when the machine is put under too much load the pad will no longer rotate saving you from burning through the paint. With such a large pad it won't take much pressure too stop it. The the larger diameter causes more leverage to be placed against the motors rotation. The further from the center the higher the speed, meaning more load. For a forced rotation machine with a strong motor that can handle the load, further from the center means faster correction (or burn through).

**Grizzly** · 03-15-2010, 10:31 PM

Originally Posted by A4 1.8tqm

Those DA's have a "safety feature", when the machine is put under too much load the pad will no longer rotate saving you from burning through the paint. With such a large pad it won't take much pressure too stop it. The the larger diameter causes more leverage to be placed against the motors rotation. The further from the center the higher the speed, meaning more load. For a forced rotation machine with a strong motor that can handle the load, further from the center means faster correction (or burn through).

I undertstand about the whole safety clutch thing but I am just trying to pinpoint the problem.

Are the 7"meguiars pads just simply too big and will bog down under pressure and stop the pad from rotating?