Many people confuse spindle and disc sander but they are two different types of sanders which are used for different purposes and you would need to choose one of them depending upon your need and project type. We are here to talk about spindle sander and it might seem to resemble a disc sander just because it is attached to the bench and is not hand held but that is where the similarity ends. If you ever have a chance of of viewing a spindle sander, you would notice that the the machine consists of a drum sander that is pretty visible and it just not moves horizontally, it moves vertically too and the motion is an oscillating one which is why it is also called an oscillating spindle sander.
You would require the best spindle sander if you work closes with uneven surfaces that are not in traditional square or rectangular shape. A spindle sander is used to deal with curved surfaces and sand it down. If you would try to sand a curved surface with any other sander, you would notice that you would need to spend a lot of effort into trying to get the job done right but the result would be poor. A curved surface is not easy to sand if you do not have the right kind of sander which is why spindle sander is available.
A good spindle sander should have a good speed range so that the sanding job can be done at a high speed too.
While choosing a spindle sander, make sure to get one that comes with different drum sizes.
Always purchase a spindle sander that can be used for hours at a time without it needing a break.