Sander sat too long I guess......

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Tom Dunn

New User
Tom Dunn
Took out the Porter Cable 333 sander yesterday to start sanding the top of a pine desk(Thrift Store find).
Been awhile since I refinished anything besides gunstocks, and was looking forward to getting on with this project. Desk was outside, beautiful day and all.
Didn't get too far along when the pad on the sander self-destructed, the foam had become soft and crumbly.
Oh well, thats on hold until the new part gets here.
Couple mouse clicks and a debit card is all it took to get it on its way to me!

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jhreed

New User
james
I would wager your problem is heat and not age. I will bet you sanded the inside bottom of a box and the edge of the pad rubbed the side of the box and got hot. That is how I destroyed mine. The pieces flying off will cause a bruise. I now stay away from cornes with my ras and use a block to hand sand these areas. The pad cost at least a third of what the ras costs.
 

ScottM

Scott
Staff member
Corporate Member
Seem to recall Klingspor stocks those replacement pads in the store. You might want give them a jingle.
 

Tom Dunn

New User
Tom Dunn
Now that you mention it, the last time this was used may well have been when sanding the pine bottom of a hope chest I had made....
 

sawman101

Bruce Swanson
Corporate Member
Klingspors does have the replacement pads in stock, fortunately for me when mine dissintegrated.
 

Alan in Little Washington

Alan Schaffter
Corporate Member
I had an old PC pad fall apart just like that. I seem to remember from my SCUBA diving days that neoprene (same as used on the pad I think) deteriorates in the presence of Ozone which is a strong oxidant present in the air in varying amounts especially near certain types of motors.

Wikipedia says: "Ozone Cracking. Ozone gas attacks any polymer possessing olefinic or double bonds within its chain structure, such as natural rubber, nitrile rubber, and styrene-butadiene rubber."

I can't say if PC sander pads fall in this category, but WP goes on to say:

"Storing rubber products in close proximity to DC electric motors can accelerate the rate at which ozone cracking occurs. The commutator of the motor creates sparks which in turn produce ozone."

The same likely goes for universal AC motors, like power the sander, which also have commutators.
 

ehpoole

Administrator
Ethan
Most foam pads will deteriorate with and exposure to pollutants. Ozone exposure from the motor is not a big contributor, but ozone exposure from polluted air will (here in Anderson, SC we are literally at the edge of non-compliance with respect to Ozone thanks to Atlanta -- rubber can break down quickly here!).

That said, it is not uncommon for the adhesive that secures either the Velcro to the pad, or the pad to the mounting plate, to fail with time on random orbital sanders -- primarily due to heat and lateral forces which tend to shear the adhesive. For that reason I always keep a couple spares on hand because I hate downtime (I only have so many good hours health wise, I don't want to waste them waiting for parts!). You may wish to store your spares in a sealed Ziploc to reduce exposure to atmospheric ozone and to slow the loss of plasticizers in the foam.

One thing to be aware of when ordering new pads is that they are typically available in 2 or 3 levels of firmness, depending upon the vendor, with "Medium" being the most commonly desired (and usually most readily available) firmness. But if you do lots of sanding on curved edges or such then a Soft pad might be more appropriate for such, though you will still want a sander equipped with a Medium pad for sanding flat surfaces.
 

Mike Davis

Mike
Corporate Member
I don't have any experience with that kind of sander, but if it was mine I think I would try a hard felt pad on it.
 

ehpoole

Administrator
Ethan
I don't have any experience with that kind of sander, but if it was mine I think I would try a hard felt pad on it.

I could certainly be wrong, but I don't think any of the major players are offering OEM felt pads for their 5" ROS sanders (at least not as a sanding attachment). I can't speak to third-party aftermarket sources though.

However, it is my understanding (and please feel free to correct me) that felt pads are primarily intended for polishing with polishing compound/grit. Nor am I certain that one could successfully attach traditional hook and loop sandpaper (which has a felt-like backing of its own) successfully to a felt pad, which would greatly limit the use of the ROS as a sander. Possibly one could use PSA sandpaper on a hard felt pad (I've never had the opportunity to try), however PSA sandpaper is not especially conducive to smaller projects unless your ROS has easily removable pads (such as on most 6" ROS sanders) where you can devote a pad to each grit.

Admittedly, my experience with felt pads has been limited primarily to use with my Dremel and Bench Grinder (for polishing), so you may be in a position to enlighten me on this topic -- and please do as I am curious!
 

Mike Davis

Mike
Corporate Member
As I said I have never used such a sander. I didn't know you have to use hook and loop sanding discs.

My 1/4 sheet pad sander had soft rubber padding which wore out several years ago and I replaced it with felt.

The sandpaper attaches with clamps so does not require special hook and loop paper.

I won't be looking at this type sander since the rubber pads are so prone to disintegration.
 

Roy G

Roy
Senior User
I had a similar problem with a PC half-sheet pad sander. The local tool repair place had replacement pads and I was back in business really quick.

Roy G
 
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