Thread: Random orbital sanders and rounded over edges

Originally Posted by Arron

If I take a nice flat board and then sand it with a ROS, what I notice is that the edges of the board have been rounded over slightly. I must stress that the rounding is very slight, especially if I make an effort to hold the sander as close to parallel to the board as one humanly can. However, the rounding is there, and when I want a flat board I want a flat one, not a very nearly flat one. I've always assumed this is just a limitation of design of any hand-held sander, but now I've decided to check with the collective wisdom of the forum. Is there a way to use a ROS to avoid this problem ?

Clamp an equal thickness board along the edge you wish to sand. Also you'll need a corner and/or other appropriate shapes to mate with. Often you can use the other pieces from the same project.

Bobs suggestion sounds like a good approach. It may also be worth checking to see if there is different density bases available for your ROS. I know with the one that I have there are a few varying "softness" ratings for the pad depending on the type of work being done.

It may be also worth checking the condition of the backing pad. I have found that when they get worn the outside edge of the sanding disk isn't fully supported and can flop around a little.

+2 BobL.

Originally Posted by Sir Stinkalot

Bobs suggestion sounds like a good approach. It may also be worth checking to see if there is different density bases available for your ROS. I know with the one that I have there are a few varying "softness" ratings for the pad depending on the type of work being done.

I agree, although some brands of ROS may not offer this option. When I bought a Festool ETS150/3 years ago it was supplied with a "general purpose" medium density pad. This would round over the edge of boards if not used very carefully, but I was told by the Festool rep. that it was intended to allow sanding of both flat and curved surfaces. While in Carbatec one day I noticed a "hard" pad for the 150/3, and bought one out of curiosity (as most of my sanding work is flat panels). Wow - it made a huge difference in terms of preventing roundover. In fact, the "hard" pad has remained on the sander ever since, and I've never gone back to the original pad supplied with the ROS.

Worth a look for other Festool ETS150/3 owners.