If you want to remove paint, rust, dirt, or welding slag without damaging the metal surface, you may need an air needle scaler. This air-powered tool has a piston that drives a number of needles or small chisels back and forth very quickly.
The model 125 needle scaler from Ingersoll Rand drives nineteen 1/8″ needles at 4,600 blows per minute. This air-hungry tool consumes 8 CFM on average, so you’re going to need a big compressor to run it.
Nine different chisel styles are available for different types of work. The model 125 needle scaler starts at $150.