What did I do wrong? [Backing plate problem]

R

Rusker

New member
This is my first time using the PC, or any machine polisher. I purchased the 7424 last year (Aug 09), and have spent a large amount of time reading about the proper techniques. I finally felt like I'd learned enough and began working on my car a few days ago. I did a few test spots, and they turned out great. Today I began to do full panels, and this happened...



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Needless to say this was caused by too much heat. How did this happen? I tried to be as careful as possible to not use too much pressure. I'm already worried enough about damaging the paint as it is. :grinno:



These are the 6.5 LC pads, with the 5in plate. The PC only came with the 5in counter weight, so that is what was on the machine.



Did I do something wrong?



I did some research before posting this ( as you should ), and I see that the LC pads are now reinforced. http://www.autopia.org/forum/autogeek-net/126990-lc-backing-plate-comparisons-new-er-da-design.html



What sucks is I only finished the hood, and fender then this happened. I can't use the car until I get it done, and I need to wait for a new backing plate. :(
 
Yes there were problems with the old LC backing plates. I switched to Meg's with no problems. I know that your not happy, but be thankful it didn't damage your paint like what happened to me.
 
Rusker, Sorry to hear that happen to you where did you get it from? maybe they can help you out in a replacement for you.
 
Using 6.5" pads on a PC is just an exercise in frustration anyhow IME. The amount of friction that results in backing plate failures also limits the amount of pressure you can apply, usually so much so that the machine merely "jiggles" with a reasonable amount of pressure.



It's best to mach plates/pads a bit more closely anyhow; 5" plates are too small (for even pressure distribution and/or to avoid "cookie cutting" the pad) for use with anything larger than 6", and even that's really too big. Via PC, 5" plates work best with 5.5" pads (and 6" plates with nothing larger than 6.6" pads).



The counterweight issue is, well...really a non-issue. Note that it's not based on those backing plates or on the use of foam pads wet with product anyhow, but rather on the OE PC-brand backing plates spinning a single sheet of sandpaper with zero applied pressure...very different from polishing cars. Remember, the PC was designed for use as a finish sander for woodworking. Even though *I* prefer a 6" weight for *all* sizes of plates/pads, the functional differences are minimal when you're talking about polishing cars.
 
When I had originally ordered the PC with the pads, I was under the impression that having slightly oversized pads was a good idea being that I'm a novice. I was worried this may cause additional stress on the machine, but figured the advice I was given was proven to be a good thing. I can see how the extra room the larger pads offer is a good thing for us beginners as to not hit the paint with the backing plate, but now that I've used it for an hour or so, I don't see how that would happen if you're using it correctly.



I ordered the kit from detailcity, which as far as I know is no longer around. Does anyone make a larger backing plate? Maybe a 6in? When I purchase new pads in the future I think I will get smaller ones that are sized with a smaller pad. The pads I have now are a bit cumbersome to use.



Does anyone sell the LC plates on the westcoast? I need to get a replacement asap. :wavey
 
Rusker- Yeah, I often just :confused: :nixweiss about the "kits" that vendors sell. You'll be a lot happier with smaller pads. Seriously, you'ljust waste time/effort/money trying to do correction with those 6.5" pads.



Dunno where you'd find stuff on the west coast (try West Coast Detail Supply Home ) but there are some good/durable plates on the market these days; LC redesigned theirs to be more durable.
 
Hopefully it was an isolated incident with the BP.....Over-stressing (too much pressure, too large a pad) can play havoc on a BP. I have to admit in all of the years I have used a PC/UDM, I have never melted a pad or BP! Remember neither pad, BP or PC is/are indestructible!
 
Whoever sold you that one sold you the older design. I melted that one early 09 and sent it back to Eric@LC so he can develop the newer version you see today. Talk to the distributor you bought that one from and ask him to send a replacement for ya ;)
 
Accumulator said:
Rusker- Yeah, I often just :confused: :nixweiss about the "kits" that vendors sell. You'll be a lot happier with smaller pads. Seriously, you'ljust waste time/effort/money trying to do correction with those 6.5" pads.



Dunno where you'd find stuff on the west coast (try West Coast Detail Supply Home ) but there are some good/durable plates on the market these days; LC redesigned theirs to be more durable.
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Yeah after a few minutes I could see that the pad combo was great for large areas, but was going to give me a problem when space was an issue.



I actually did contact WCD, and placed an order. I'm hoping to have that today. Great guy btw! Probably would have showed up yesterday had it not been a postal holiday.
 
eyezack87 said:
Whoever sold you that one sold you the older design. I melted that one early 09 and sent it back to Eric@LC so he can develop the newer version you see today. Talk to the distributor you bought that one from and ask him to send a replacement for ya ;)
Click to expand...



Detail city is who I purchased it from. They are no longer around as far as I know.



I'm amazed it melted off because I was not using very much pressure at all. I was even doing a door panel when it happened. Oh well.. hopefully the replacement is the last one I'll ever buy.
 
How did you have yours for a couple of years? Does yours have the rivets like it does in the photo? Mine did not.
 
Rusker said:
Detail city is who I purchased it from. They are no longer around as far as I know.



I'm amazed it melted off because I was not using very much pressure at all. I was even doing a door panel when it happened. Oh well.. hopefully the replacement is the last one I'll ever buy.
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Send Eric an email. It wouldn't hurt to try. eric@lakecountrymfg.com
 
I used to love using my pc (xp and not)...I thought it was easy and safe to use. But over the years I am finding that it can still pose a serious threat to paints. Whereas the rotary performs great correction abilities at less than 2000rpm's (depending on product and pad choice of course), the pc needs a speed of 6 to perform any significant correction. A speed of 6 means the pad is spinning 3x as fast as on rotary. This means an exponentially greater wear and tear factor with the pc. These days I am afraid to use a speed of 6 on my xp because even new pad velcro glue quickly looses grip on the foam itself and at such a high speed you can feel the pad distort in a very odd manner, and then you can see the pad distorting at speed. Even with light pressure and constant checking to ensure the pad is spinning properly the pad overheats and starts to distort. Has anybody else notice this distortion that I describe? There is a significant change in the sound of the pad's noise when it is spinning on the surface when this is happen and it's something that has made me turn my pack to the trusty old pc!
 
xfire said:
I used to love using my pc (xp and not)...I thought it was easy and safe to use. But over the years I am finding that it can still pose a serious threat to paints. Whereas the rotary performs great correction abilities at less than 2000rpm's (depending on product and pad choice of course), the pc needs a speed of 6 to perform any significant correction. A speed of 6 means the pad is spinning 3x as fast as on rotary. This means an exponentially greater wear and tear factor with the pc...
Click to expand...



IMO you can't make a direct comparison between a rotary's RPMs and a PC's OPBs. Given the same pads/product, PC at speed 6 is, IME, a lot more gentle than a rotary at 2000 RPMs (or even much lower speeds). Whole lotta functional differences.



These days I am afraid to use a speed of 6 on my xp because even new pad velcro glue quickly looses grip on the foam itself and at such a high speed you can feel the pad distort in a very odd manner, and then you can see the pad distorting at speed. Even with light pressure and constant checking to ensure the pad is spinning properly the pad overheats and starts to distort. Has anybody else notice this distortion that I describe? There is a significant change in the sound of the pad's noise when it is spinning on the surface when this is happen and it's something that has made me turn my pack to the trusty old pc!
Click to expand...



While I do use lower speeds with 4" pads, any distortion of the pad seems pretty inconsequential to me and I just don't worry about that. If you prefer lower speeds, I'd just use those. Not sure why you're having heat issues or velcro failures :confused:
 
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