Post drilling out counter weight for 5 inch backing plan

[William_Wallace]

What started from a Slight thought grew into quite the itch to try to tinker with my counter weight. I run a shurhold 21mm I love the Machine it’s made for boating industry and has a lot of torque not as smooth as rupes but more powerful and cheaper never stalls or stops it’s free rotation. Made for 6 inch wool bonnets. I got to thinking I’m running 5 inch foams maybe play around with the counter weight during its next greasing and tear down.

I came up with a plan to drill 1/6 of weight off. For 6 inch to 5 inch thought but then I could not find a scale small enough to weight it. So I put it in drill press and this is what I came up with. Which is not even close to the 1/6 removal but Im glad I stopped it seems a bit excessive removing 1/6 weight

 

[Lonnie]

The "engineer" in me would have moved the two drilled holes to be half-way radius arc on the "weighted" area on bisected lines between the countersunk mounting holes centerlines in order to maintain some of the center-of-gravity designed into the original counterweight for a 6" pad. Just because 1 inch is "lost" in the difference of a 5" versus a 6" pad does not represent a lost of 1/6th the weight between the pads, although it is a good "guesstamate."

The "best" way to actually measure the weight difference between a 5" pad and backing plate assembly versus an identical (foam type and thickness) 6" pad/plate assembly is to weight them on a digital kitchen in grams and subtract the two weights and divide it by the 6" foam/plate assy. This will give you the percentage of change in the two weights of the pad/plate assemblies, which could then be used as the percentage of the total weight to remove (or drill out, as you have done) from the 6"-specific counterweight.

The other thing to consider is that a 6" pad that spins/rotates/orbits on a polisher may exhibit more "vibration" at the same rotating speed (Revolutions per Minute) as the 5" pad due to the longer due to the longer moment arm, which is what the counterweight is trying to negate with the orbital motion or stroke, depending on the design of the polisher with an 8mm, 9mm, 12mm, 15mm or 21mm stroke.

If it sounds like rocket science, it kinds is. A lot of testing goes into "designing" an optimal counterweight to balance out pad vibrations and make the polisher as smooth as possible. This is most evident in the ingenious design of three (3) "weighted" and color-coded user-changeable screws in the counterweight used on the new Griot`s Garage BOSS G15-V2 (my designation!) and G21-V2 for use with their different pad types and thicknesses.

 

[William_Wallace]

Very helpful info I went center as far out as possible I was also thinking a hole on each corner but was to worried about no being able to drill the depth right on and have to worry about that. My original plane was to drill in horizontally with one hole but couldn’t get it to clamp tightly enough on press I’ll try in tomorrow I have thread locker on the counter weight bolts trying.

 

[William_Wallace]

Hey you know what I have a Griot’s 6 inch 8m throw that I run a three in pad on. Now that needs some machining the vibration is almost to high to use. Will I ever go back to a 5 inch plate on there don’t think so. So I may try your method with a large bit either 1/2 bit or Larger

 

[Accumulator]

Hey you know what I have a Griot’s 6 inch 8m throw that I run a three in pad on. Now that needs some machining the vibration is almost to high to use..

That unit sure does get work done faster with a smaller plate/pad all right! Though huh, that`s interesting about the vibration being so severe with a 3"...I`ve only used it with a 4" one myself. Although I`m kinda sensitive to such vibration I never had a problem it with that unit using the 4" pads, although the smaller plate/pad was a bit more noticeable on the GG6 than on my PCs.

(I tried different counterweights on the PCs without any of them making enough diff to bother with.)

I wonder whether the diff here is between William_Wallace/Accumulator with regard to sensitivity, or whether going 3" is just a bit too much for that unit compared to a 4".

 

[William_Wallace]

Boredom is the ultimate motivator in my case but drilling out the counter weight on the 21mm Did not have any positive effect on the 21mm I might even say it had a negative effect I wouldn’t recommend messing with counter weights in hindsight I would have been better drilling a hole on top left corner and top right corner.

But my Griot’s with a 3 in has too much vibration it’s not that bad under speed 4 but anything above that I feel like I can damage it.

 

[Accumulator]

Boredom is the ultimate motivator in my case..

I`ve heard about that "boredom" stuff....wonder what it`s like? I gather it bugs people...

but drilling out the counter weight on the 21mm Did not have any positive effect on the 21mm I might even say it had a negative effect I wouldn’t recommend messing with counter weights in hindsight I would have been better drilling a hole on top left corner and top right corner.

Well, at least you found *that* out...might be useful info to people who`re dealing with that vibration..no sense in working to make things worse! Too bad you didn`t solve your problem though...

Next time I have to do some spot-correction (hopefully not any time soon!) I`ll have to see what plates I have...I always just do it by hand or stick a pad on my 3" pneumatic, but I might have a plate for the PC/etc. that I can try on my GG6.