washer on PC 7424

**ScottB** · 07-04-2009, 09:57 AM

Originally Posted by loudog2

I thought that was from the KB method

I have heard that also ... funny how durable the PC was until this method came around.

**loudog2** · 07-04-2009, 10:09 AM

Tools are meant to be used the way they're built for. It's equal to jamming a circular saw into a concrete block w/a wood blade.

**tktlau** · 09-20-2009, 02:37 PM

Originally Posted by killrwheels@autogeek

There is indeed a washer and noted in instructions to install it. Several that have failed to use it have suggested some overheating, hot, or burning smells.

It's supposed to put between the backing plate and the PC, right? I can't find the instruction from the manual though.
http://www.autogeekonline.net/Downlo...4xp-manual.pdf

Thanks!

**Rsurfer** · 09-20-2009, 02:47 PM

Originally Posted by tktlau

It's supposed to put between the backing plate and the PC, right? I can't find the instruction from the manual though.
http://www.autogeekonline.net/Downlo...4xp-manual.pdf

Thanks!

Yes, the washer goes between the bp and the pc spindle.

**ThomasonCarCare** · 03-06-2014, 03:08 PM

Here is the link to the part.

Detail

Mike Phillips · 03-06-2014, 03:32 PM

I have two articles on this topic...

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.

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

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

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

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.

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

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

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

Mike Phillips · 03-06-2014, 03:32 PM

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

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.

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.

Mike Phillips · 03-06-2014, 03:34 PM

Here's the other article...

Don't use your polisher without it!

That is... the Compression Washer

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

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.

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.

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.

Mike Phillips · 03-06-2014, 03:43 PM

one more...

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,