Yes, it should be able to function in that position. However, this will play a factor in how much control you have over the machine while working. If it's a free-standing belt sander, then you can use it vertically without any problems. But if there is a stand involved, make sure the base is wide enough to stand properly and not topple over. But do so with extra care because using it this way will cause the belt sander to function at a much higher RPM. This leads to an increased risk of kickback, so being more cautious is necessary when using it in this position.