Disk sanders are so useful. I bought one ten years ago and despite sanding a knuckle soon after buying it, I have never looked back. In fact, I only recently changed the disk. I have a small pece of MDF that I place on the bed wen sanding small pieces so they don't get pulled down between the bed and the spinning disk to their destruction.
I reccomend you use a vacuum cleaner (Wickes sell a basic one that makes a good one) as an extractor and make sure to clean any wood dust out of it before sanding any metal as it can cause a fire, as testafied by Northbrook college (West Sussex) losing two extractor systems in as many years due to morons doing just this despite being told not to.