The Compression Washer

[Mike Phillips]

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

[shoeless89]

Thanks Mike! Do you know any specifics on WHY its so important it is to have? What does it do exactly and how does it prevent damage to pads, the polisher, etc.? Thanks!

[Mike Phillips]

Thanks Mike! Do you know any specifics on WHY its so important it is to have? What does it do exactly and how does it prevent damage to pads, the polisher, etc.? Thanks!

Great question!

I actually included that in this article but now it's in this article too...




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.

[Hoytman]

Mike,
When I ordered my dynabrade attachment for my rotary I'm fairly certain it came with a steel washer.

Without looking, I'm uncertain what type of washer came with my G110V2, but I'm sure they all come with the same washer from the factory whatever type that may be.

Having worked along side toolmakers in a maintenance setting I've always understood the use of the term "compression washer" to mean exactly as you've described above. In addition to that I've always understood that these compression washers, at least in a toolmaking and maintenance setting, can and do wear out over time through continous over tightening. My understanding is that they are designed this way on purpose and are intended to be replaced periodically.

By being crushable I've noticed that they also tend to work similar to a lock washer or spring washer in that they help keep things snug, to keep it simple.

I wonder why Dynabrade sent a steel washer with my rotary attachment? It does seem sort of odd.

I have material that if I needed to I can make a washer. It's also just as easy for me to go to ACE Hardware, or Lowe's. I would think that if a person needed to they could order these items from the factory. It would be nice if AG could carry replacement washers. At least they'd be a cheap item and orders for them could be placed along with other product orders. Perhaps that would be a convenience to some folks who may place product orders that may not necessarily want to make a special trip for just a washer. Just a thought. I understand that it also may not be worth it for AG to carry these items.

[Mike Phillips]

Mike,


I've always understood that these compression washers, at least in a toolmaking and maintenance setting, can and do wear out over time through continuous over tightening.

My understanding is that they are designed this way on purpose and are intended to be replaced periodically.

That is correct. Because the washers compress when tightened, they do flatten out and then stop compressing over time and for this reason it's a good idea for high volume users to have a few spares on hand.

[spyghost]

How about this one? - PC7424XP Plastic Washer

This on the other hand came with the PC, easily missed because it's small and located in the accessories bag.



It's small in diameter, but thicker compared to the one that came with the BP.

I reckon either of which can be used but not both at the same time.

[shoeless89]

Thanks for clarifying Mike!

How about this one? - PC7424XP Plastic Washer

This on the other hand came with the PC, easily missed because it's small and located in the accessories bag.



It's small in diameter, but thicker compared to the one that came with the BP.

I reckon either of which can be used but not both at the same time.

Yeah I have one of those too and I'm not exactly sure if I need it or not. I've been running my PC for over 2 years without it and still running great! But still not really sure what its for lol

[theamcguy]

Where can new ones be purchased?

[feslope]

Where can new ones be purchased?

+1

[BillE]

To those looking for new washers...check out the plumbing section of you local hardware store.

The stock washer measured> .070" thick, .930" outside diameter, with about .30" hole-this a tad on the tight side, probably from being compressed. But it will be for a 5/16-24 'bolt'.

Bill