New sander's backer pad is cupped right out of the box!

[KingwoodFan1989]

Alright, so I ended up buying the cheaper of the two Bosch ROS I was asking about here. The reviews overall were good, and honestly, as alluring as the $128 one was (along with a few recommendations I got on here for it), I don't feel like I could ever justify spending that much on a sander. A select few reviews said their pads were cupped, but that was possibly around 1% of the reviews. Since I had gotten a gift card for Amazon for Christmas, I decided to get it off there since it covered most of the cost of that sander.

I will admit the sander runs VERY smoothly and is comfortable to use. However, I checked the sanding pad with a straightedge and it's quite flared up at the edges to the point where you get about 1/16" of a gap across pretty much the whole center. As expected, it only sands around the edges, which can (and does, based on what I saw while trying it out) make the sanding very uneven. It was a bit awkward to get a picture of it, but I got a clear one. It looks even more pronounced in person, but you can see how significant that gap is.

I contacted Bosch about getting a replacement pad. I actually asked them about picking one up in a store since I'd rather test the pad with a straightedge myself and then get it. Just not sure if I can avoid spending $10 more that way. Still glad I got the sander as it runs VERY well, but at the same time it's kinda frustrating to get a defective pad with a brand new machine.

[ez-duzit]

What is the country of origin on this machine?

[KingwoodFan1989]

What is the country of origin on this machine?

I have no idea. I'll check tomorrow. I'm already in bed. 

[EvilTwin]

So I'm guessing you bought the Bosch ROS20VSK. If I am wrong then please disregard all that follows....


Not to be too hard, but you get what you pay for, in this case, a 50 dollar sander.  The cupping seems to be a "feature", not a "bug".  Sander made in Malaysia.  I've got other Bosch tools from Malaysia, they are fine, but I also have Bosch tools that are Swiss or German in origin and I prefer those.

From the Q&A on Amazon:

Question: Is 1/16" cupping in the disc normal?
Answer: 

I would say that a small amout of "cupping" is normal. As to 1/16 of an inch, I think that is a little much. Most of the sanding takes place on the outer edge of the disc. As it rotates the dust is sucked into the 8 holes in the center of the disc. In order to flatten out the disc, you would have to put more pressu… see more
By looseknot on September 23, 2013

I thing is normal, this is my third orbital sender and all of them did this. I believe it helps with dust collection and control.
By Luk on October 3, 2013

I would say yes. As you sand, the weight of the tool and your hand on it, automatically applies a little downward pressure, flattening the disk out again. The cupping helps to keep the edges of the disk in contact with the work.
By Mike on September 23, 2013

[ez-duzit]

...I'm guessing you bought the Bosch ROS20VSK...you get what you pay for, in this case, a 50 dollar sander...made in Malaysia...

My guess too.

[Stwood_]

Sorry, but it hardly ever pays to go cheaper

[Strokes77]

In retrospect, I just bought a new sanding pad for my sander.. the pad alone was $47...

But it's "flat"..

[BloomingtonMike]

Id not use that rule as a reference edge either.

[KingwoodFan1989]

What’s wrong with using that rule as a straightedge?

Also, Bosch got back to me and I can get a replacement. I think I’m gonna talk to them over the phone about it, though. I need to be sure they’ve checked the exact pad they’re sending me for flatness.

[packerguy®]

Alright, so I ended up buying the cheaper of the two Bosch ROS I was asking about here. The reviews overall were good, and honestly, as alluring as the $128 one was (along with a few recommendations I got on here for it), I don't feel like I could ever justify spending that much on a sander. A select few reviews said their pads were cupped, but that was possibly around 1% of the reviews. Since I had gotten a gift card for Amazon for Christmas, I decided to get it off there since it covered most of the cost of that sander.

I will admit the sander runs VERY smoothly and is comfortable to use. However, I checked the sanding pad with a straightedge and it's quite flared up at the edges to the point where you get about 1/16" of a gap across pretty much the whole center. As expected, it only sands around the edges, which can (and does, based on what I saw while trying it out) make the sanding very uneven. It was a bit awkward to get a picture of it, but I got a clear one. It looks even more pronounced in person, but you can see how significant that gap is.

I contacted Bosch about getting a replacement pad. I actually asked them about picking one up in a store since I'd rather test the pad with a straightedge myself and then get it. Just not sure if I can avoid spending $10 more that way. Still glad I got the sander as it runs VERY well, but at the same time it's kinda frustrating to get a defective pad with a brand new machine.

I always am taken back how guys find things that aren't "perfect". I've never once checked a pad for "flatness" (or even considered it). 

Id be willing to bet it would work just fine though....but what do I know.