I have been asked a few times which is better, a random orbit sander or a finishing or sheet sander? It is a very reasonable question and one I will do my best to answer here. Below I have shown two images.
The one on the left is a finish or sheet sander, and the one on the right is a random orbital sander.
[table id=2 /]
As you can see they look quite different. The sheet sander has been around for a very long time, and the random model has now all but replaced it as a tool for woodworkers. Now not everyone will agree with that, and some woodworkers will argue, that each of these have their own uses.
Let’s try and understand what they mean when they make that argument.
The Finish Sander
As you can see the finish type of sanders have a square bottom and sometimes it may be rectangular. It works by simply moving backwards and forwards over the surface. That type of restricted movement will leave swirl marks as it is quickly and constantly repeating an exact motion.
The random model moves both circular and in an oval pattern to help reduce swirling. As such it will leave a better finish in my opinion.
Now all of that said, the random models do remove stock faster and as such are considered to be more aggressive. You need more skill to be able to master using one of those.
Now it doesn’t take that long to learn this, and by practising on old wood, you can quickly get the hang of it. A typical time to learn how to use one of these random styles is about a couple of hours.
That will get you to understand the feel of your tool, and then after that more practise will simply make you much better. The finish sander is easier to control and not as aggressive on the wooden surface.
When To Use A Finish Sander
Now there is only one time when I would ever consider using a finishing sander. I use the random one for all my stock removal and for all my finishing work as well. However, there is one place where I am forced to use a finishing type.
If you have to get into a square corner such as on a dressing table, and certain cabinets, then you need the square bottom finish.
The random base and pads are all round so you can not get right into the corners. The random orbital sanders generally have a point, but that can be very fiddly when working right into a corner, or going along a ridge of wood.
So where two pieces of wood meet at different heights, and you want to do a long edge, I will use a finishing sander.
Thankfully I don’t have to do that too often, and unless you have to do this regularly, then I would buy and stick with a random orbital sander, as it does a much better job of a smooth finish.
All the new random models use special sandpaper discs which attach by velcro using the hook and loop system. These have advantages in that they are quick and easy to change, but you are also forced to buy these.
With the finishing sanders, you can also buy paper to fit, but you can also cut up and use any sandpaper that you may have. That makes them slightly cheaper to use.
That said, it is usually a pain in the ass to change. As you can see from the image on the left, they use levers to lock the paper in place and that can be very fiddly.
Ideally you should have one of each and all woodworkers will have those. However, if you just want to buy one, then absolutely go for the random one. It is just better and leaves a much better finish. Remember though that if you need to get into corners, then the only one that will do that is the finishing type.