Change your counterweight...NOW!
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Corey Bit Spank
Active member
Hmmm, I have the 6" counterweight and gosh does that thing vibrate. My right and hurts meh 
After reading this thread and 4DSC's PC vibration thread, I thought I'd change my weight [bought from coastal tool and have both weights]. I just weighed the PC 6" backing plate on a postal scale and came up with this...
6" Porter Cable 18002 Contour Backing Pad: 5 oz / 142g
ouch...
Lets just hope this scale wasn't very accurate...although I did come up with similar figures for the counterweights.
It is as heavy as it looks.
I haven't given it a test run with the weight yet...and I've only been using the included Porter Cable pad...haven't gotten velcro pads yet. I wonder if the vibrations will go up when I switch to PC hook & loop backing plate and velcro pads...I hope it is not a lot!
Kev
6" Porter Cable 18002 Contour Backing Pad: 5 oz / 142g
ouch...
Lets just hope this scale wasn't very accurate...although I did come up with similar figures for the counterweights.
It is as heavy as it looks.
I haven't given it a test run with the weight yet...and I've only been using the included Porter Cable pad...haven't gotten velcro pads yet. I wonder if the vibrations will go up when I switch to PC hook & loop backing plate and velcro pads...I hope it is not a lot!
Kev
:wavey
I just used my PC with 6" backing plate and hook and loop pads for the first time. I held off on getting the 6" counter weight because of all the controversy in forums. I started out using DACP with a cutting pad at about #3 speed, then as the product began to break down I turned up the speed to #5.:scared The PC shook so bad I almost couldn't hang on to it. I finished the car at no higher than #4. Vibration was still bad, but at least it was controlable. I will get the 6" counter weight, right away. I'll let you know if it calms down any.
I just used my PC with 6" backing plate and hook and loop pads for the first time. I held off on getting the 6" counter weight because of all the controversy in forums. I started out using DACP with a cutting pad at about #3 speed, then as the product began to break down I turned up the speed to #5.:scared The PC shook so bad I almost couldn't hang on to it. I finished the car at no higher than #4. Vibration was still bad, but at least it was controlable. I will get the 6" counter weight, right away. I'll let you know if it calms down any.
imported_memnuts
New member
As you become more experienced with the PC the vibration will decrease. Not in absolute terms but the way in which you hold the machine and pressure applied to the surface you are polishing. It will always "jiggle" as Mike states 
but more work will go into polishing (pressure and confidence) and less into wasted motion (vibration and fear of doing some harm). JMHO :wavey
but more work will go into polishing (pressure and confidence) and less into wasted motion (vibration and fear of doing some harm). JMHO :waveyWhat controversy? :nixweiss I think it's only logical that the larger counterweight be used, especially in your case with the 6" diameter backing plate.PATHFNDR said:
Look at it this way: Those counterweights were designed assuming you would be using the PC for sanding, using PSA sanding discs, as the PC was originally designed to do. Those sanding discs weigh next to nothing compared to a 6.5" or even 8" foam buffer pad loaded up with product. It's going to need a heavier weight to deal with this extra mass.
If you're curious, in my PC thread linked below there is a link to a vibration test I ran. I noticed quite a bit of difference at high speeds with the 6" weight. Not a total elimination of vibration, but it was at least livable. Get that weight! :xyxthumbs
Since there are so many combinations of plates and pads and as many opinions on what to base your counterweight size on, how can you go wrong by having both counterweights (since they're only about 3 bucks)?
If you get vibration with your pad/ backing plate combo, then just switch to the other countrweight.
For me, the combination of a 5" backing plate and a 6.5" pad requires the 6" counterweight. When I use the PC for sanding with the same 5" backing plate and 5" sanding discs, it works best with the 5" counterweight.
Spend the $3, its well worth trying for yourself.
If you get vibration with your pad/ backing plate combo, then just switch to the other countrweight.
For me, the combination of a 5" backing plate and a 6.5" pad requires the 6" counterweight. When I use the PC for sanding with the same 5" backing plate and 5" sanding discs, it works best with the 5" counterweight.
Spend the $3, its well worth trying for yourself.
imported_kgb
New member
I was using 6" pads with a 5" packing plate and 5" weight then switched to a 6" weight and the machined became so much smoother it was eally nice. Now I use the 7.5" pads, 6"backing plate, and 6" weight and that is smooth too.
togwt
The Old Grey Whistle Test
~One man’s opinion~
This says it all for me;
The PC 7424 comes with a 5� counter weight (the 7336 has a 6� counterweight) Most buffing pads are 6" + in diameter, and thus, your PC should have a 6" counterweight. Some will argue that the 5" counterweight is fine for 6" pad use; however, it's been proven to be untrue. The vibrations that are generated at higher speeds when using a 5" weight and a 6" pad are unacceptable for most people. The counterweight is necessary because of the orbital motion of the pad; the bigger the pad, the more counterweight required. A Porter-Cable company representative confirms that the increased vibrations can lead to bearing damage within the PC's drive assembly. My advice, use the right counterweight. The cost is negligible ($7:00); change them with a #15 TORX driver.
Experience unshared; is knowledge wasted…/
justadumbarchitect
This says it all for me;
The PC 7424 comes with a 5� counter weight (the 7336 has a 6� counterweight) Most buffing pads are 6" + in diameter, and thus, your PC should have a 6" counterweight. Some will argue that the 5" counterweight is fine for 6" pad use; however, it's been proven to be untrue. The vibrations that are generated at higher speeds when using a 5" weight and a 6" pad are unacceptable for most people. The counterweight is necessary because of the orbital motion of the pad; the bigger the pad, the more counterweight required. A Porter-Cable company representative confirms that the increased vibrations can lead to bearing damage within the PC's drive assembly. My advice, use the right counterweight. The cost is negligible ($7:00); change them with a #15 TORX driver.
Experience unshared; is knowledge wasted…/
justadumbarchitect