If you do any amount of scratchbuilding, building wooden ships, rc airplanes, or basically MAKING anything ... you’ll more than likely want to add a sanding machine to your shop. There’s certainly no shortage of machines ... many of which are easily available at your local home improvement store or discount tool outlet. If you look online, you can be overwhelmed. Quality is pretty hit or miss and usually consistent with the low price.
Most all sanding machines fall into three basic types ... Disc ... Belt ... or Spindle. The most common sanding machines out there are these inexpensive combination belt and disc type. At first glance it seems like a pretty good idea ... two for the price of one. Probably the fastest way to sort it out is to start with the features that would be best to have for a model making sander.
In my case, since I build with a variety of materials ...the one absolute requirement ... the one deal breaker ... is speed control. Although usually listed in RPMs ... the critical speed with a sanding machine is the speed of the abrasive surface. In the case of a belt or spindle sander, the speed is the same across the entire abrasive surface. However, with a disc sander, the surface speed is greater to the outside of the disc. So if you’re working with a plastic, you will probably want to stay closer to the center of the disc. The speed can be controlled either electrically or with a belt system. Unfortunately almost all inexpensive small combination sanders use a direct drive AC motor that only runs at 3450. As long as you’re careful, that speed works OK for wood. But if you try to sand any sort of plastic, you’ll wind up melting it in no time flat.
Like any tool, using a sanding machine means developing some skill and technique. How comfortable you are around the machine and the feel you develop for feeding the material will go a long way to the success you’ll have using a sanding machine. But you need to have a machine that provides a very consistent abrasive surface so you can accurately work up to your line, dust off few thousandths or correct or correct that angle a few degrees.