Groit's DA Melted my Backing Plate

Tight Loops

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I got the Groit's Garage DA polisher from Auto Geek and tried using it for the first time yesterday. I was using the first stage of Meguiar's DA microfiber kit... About 20 minutes in the backing plate started flopping all around. The tool got so hot it melted the backing plate. Was this something avoidable on my end? What could have I have done different, if anything. Here is the melted backing plate:


No_Compression_Washer_00.jpg


I also need some advice:

The car is half done on the first stage of the two stage Meg DA kit... The 5 inch backing plate is toast. What do I do with the half of the car that just got compounded? I have the 6 inch plate that came with the tool with and a polishing ***foam pad***. Do I finish the compounded half of the car with the Meg Microfiber polish, use the CG Blacklight I have, or go to the store for some glaze?
 
Hi, welcome to Autogeek! Did you have a washer on the backing plate when you started?
 
See the gouge in the counterweight?

That's a sign you didn't have the compression washer in place and the friction between the rivets on the backing plate and the counterweight created the heat.

It should have been really noisy too...


Where is the compression washer that came with your backing plate?


:dunno:
 
The Compression Washer

I wrote an article about Compression Washers explaining how important it is to the function of DA Polishers here,

Don't use your polisher without it!

There were some further follow-up questions about compression washers so here's some more pictures and information to make sure everyone's clear on what the compression washer is, where it goes and why it's important.


The common Compression Washer used with popular DA Polishers is about the size of a U.S. Quarter.
CompressionWasher001.jpg




One side of the compression washer is going to seat against the free floating spindle seen in the picture below.
CompressionWasher002.jpg




The other side of the compression washer will seat against the small steel attachment plate on the back of a backing plate.
CompressionWasher003.jpg




It would look like this without the backing plate in the way...
CompressionWasher004.jpg



CompressionWasher005.jpg



Normally you would slide the compression washer over the threaded portion of the backing plate and then align this to the spindle on the polisher and tighten together.
CompressionWasher006.jpg



Nylon Compression Washer
Here you can see where after tightening the compression washer has an imprint from where it was crushed during tightening.
CompressionWasher007.jpg



Fiber Compression Washer
Here you can see where after tightening the compression washer has an imprint from where it was crushed during tightening.
CompressionWasher008.jpg




Do's and Don'ts
  • Do use a compression washer between the backing plate and the spindle.
  • Don't use a steel washer if you lose the compression washer.
Compression washers do wear out with use, that is if you remove and replace backing plates often you're going to wear your compression washer out.



Autogeek carries replacements...

Lake Country Compression Washers 5-Pack
 
Don't use your polisher without it!


That is... the Compression Washer
5inchbackingpatesonDAPs013.jpg



If you don't use a compression washer, the rivets on the backing plate attachment base will come into contact with the counterweight assembly on your DA Polisher.

Damage caused by not using the Compression Washer
DamagedCounterweight01.jpg



Damaged and Gouged Metal
The rivets have gouged the metal because the compression washer was left off. Not only does it gouge the metal it will usually make a horrible noise and that should be your first clue to turn the polisher off and inspect for issues.
DamagedCounterweight02.jpg




Treat the compression washer like GOLD. Don't lose it.


Keep the little rubber nut to lock it into place when not using that backing plate. It's probably more likely you'll own more backing plates into the future than less likely.

The Rubber Nut - Keeps the Compression Washer from getting lost and protects the threads when the backing plate is not in use.
5inchbackingpatesonDAPs012.jpg


I have scads of backing plates in drawer in the studio and it's nice reaching for a backing plate and having the spacer washer intact with the backing plate.



The Purpose of the Compression Washer

The compression washer performs multiple functions,


Crushable Interface
The compression washer provides a crushable or malleable interface between two pieces of metal that are going to see a lot of pressure from being tightened together with a wrench and my guess is a lot of punishment from the operator. I punish all my tools... so it's not a reach to think others are going to punish their's too. Add to the above mix, the violent oscillating action of the tool on the highest speed setting and add to that t-i-m-e...

By time, I mean putting your polisher to work buffing out a car section-by-section, panel-after-panel. As Pros know and anyone that wants to get the job in a decent amount of time, when you start buffing out a car you have to keep the tool running and buffing on paint. There's no breaks. That's time of endured punishment.

Point being is you want and need the crushable interface between two pieces of metal on an electric tool capable of running at high OPM's.


Spacer
They also act as an actual spacer between the arbor or stud seat where there are the raised heads of a type of rivet or brad that anchors the arbor base to the the backing plate and the threaded portion of the Free Rotating Spindle Bearing Assembly.


Free Rotating Spindle Bearing Assembly
FreeRotatingSpingleAssembley004.jpg




Here you can see a compression washer seated at the base or seat of the 5/16" arbor or stud where it's attached into the backing plate surrounded by the raised heads of the rivets or attachment anchors.
5_0BackingPlates06.jpg




So keep track of both the compression washer and the rubber nut and don't use your DA Polisher, be it a Porter Cable, Meguiar's or Griot's without it.


Compression washers do wear out with use, that is if you remove and replace backing plates often you're going to wear your compression washer out.



Autogeek carries replacements...

Lake Country Compression Washers 5-Pack





:xyxthumbs:
 
That backing plate should have came with a Rubber Nut that holds the washer in place.

That looks like a Meguiar's backing plate and I"m holding a new one in the package and it does in fact have a rubber nut on the threads holding the washer in place.


Here's an article I wrote on the rubber nut... :D


Tip: Rubber Nut to protect threads and safeguard compression washer

When you purchase a backing plate for your DA Polisher it comes with a Compression Washer held in place with a Rubber Nut.

Here's a tip, when using your backing plate keep the rubber nut in a safe place for use later.

The Rubber Nut does two things,
  • Protects the threads on the backing plate when the backing plate is not in use.
  • Holds the Compression Washer in place so it does not get lost when the backing plate is not in use.
RubberNut01.jpg


RubberNut02.jpg



Backing Plates on Autogeek.net

Lake Country 5" DA Backing Plate

Lake Country 3" DA Backing Plate

Lake Country 3.5 " DA Backing Plate

Lake Country 6" DA Backing Plate

Meguiars W67DA G110 DA Polisher 5 inch Backing Plate

The Black Dual Action 5 Inch HD Backing Plate

Dual Action 6 Inch HD Backing Plate

Meguiars W68DA Dual Action Backing Plate

3M Hook-It 5 Inch Dual Action Backing Plate - 5775

3M Hook-It 6 Inch Dual Action Backing Plate - 5776



Related articles...

The Compression Washer

Don't use your polisher without it!

5 inch Backing Plates on Meguiar's, Griot's and Porter Cable DA Polishers




:xyxthumbs:
 
It looks like from the DA itself that the backing plate was coming into contact with the metal in the DA. Even if the washer was in place, you may have needed a second one to ensure clearance.
 
Yep, no washer. The PC7424 does the same thing when no washer is in place.
 
I got the Groit's Garage DA polisher from Auto Geek and tried using it for the first time yesterday. I was using the first stage of Meguiar's DA microfiber kit... About 20 minutes in the backing plate started flopping all around. The tool got so hot it melted the backing plate. Was this something avoidable on my end? What could have I have done different, if anything. Here is the melted backing plate:

You'll need to get another backing plate and be sure not to lose the compression washer and it's actually very important.


I also need some advice:

The car is half done on the first stage of the two stage Meg DA kit... The 5 inch backing plate is toast.

What do I do with the half of the car that just got compounded? I have the 6 inch plate that came with the tool with and a polishing ***foam pad***.

Do I finish the compounded half of the car with the Meg Microfiber polish, use the CG Blacklight I have, or go to the store for some glaze?

If the foam pad you have will fit on the 6" backing plate then

Something is better than nothing


By that I mean, the paint will be better or more protected if you finish polishing it with something versus nothing. The idea to make it smoother and then seal it with something that is not water soluble.


Sorry to hear of the mishap... part of the learning curve.

Since this was your first post to the forum....


Welcome to AGO!


:welcome:
 
Looks like you may want a new counter weight as well. Although, I doubt the one on there would cause any issue the way it is.
 
Thanks Mike. The compression washer is on my workbench where I assembled/dissembled the polisher. I can't remember if i put it on or not. I can assume with your experience, you are in fact correct that I must have left it off. What about the second part of my question. What do I do in the meantime? Blacklight, Megs DA with foam, or something else?
 
Thanks Mike. The compression washer is on my workbench where I assembled/dissembled the polisher. I can't remember if i put it on or not. I can assume with your experience, you are in fact correct that I must have left it off. What about the second part of my question. What do I do in the meantime? Blacklight, Megs DA with foam, or something else?

You need a new BP. You may be able to find a 6" one locally by Megs or 3M - which will work as long as it's for a DA and has "Velcro". You already have the washer. Or, if you can wait order one from AG. That BP is toast - I wouldn't use it anymore.
 
Thanks Mike. The compression washer is on my workbench where I assembled/dissembled the polisher. I can't remember if i put it on or not. I can assume with your experience, you are in fact correct that I must have left it off.

From the scarring on the counterweight it looks like you left it off.

If you had installed it you would see the squish impression on the washer itself.



What about the second part of my question. What do I do in the meantime? Blacklight, Megs DA with foam, or something else?

If you look above your post, you'll see I answered you. Probably while you were typing this...


:)
 
Looks like you may want a new counter weight as well.

Although, I doubt the one on there would cause any issue the way it is.


Here's the counterweight on the OP's polisher....

No_Compression_Washer_01.jpg





Although scarred I wouldn't bother replacing it. I've seen a lot of this in my life and I've never seen it cause any problems. Just be sure to keep track of the compression washer.

If anyone reading this into the future loses or can't find the compression washer that came with the backing plate you can get replacements here.

Lake Country Compression Washers 5-Pack

Compression_Washers_For_Dual_Action_Polishers.jpg




:)
 
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