Can I restring my classical/Spanish guitar with metal acoustic guitar strings?”
…but it’s the kind of thing that might be interesting if the guitar has no value anyway. Steel-strung guitars have a metal tension rod in the neck to balance the tension of metal strings. Classical guitars do not have this tension rod, so my conclusion is that if I put metal strings on a classical and brought them up to tune, something undesirable would happen. It also occurs to me that all the steel guitars I’ve ever seen have tuning pegs of a certain design (as well as being metal). Classical guitars have different tuning pegs, which may only be cosmetic (and they are not metal) but I also suspect the cogs have less resistance, making it hard to keep it in tune. I don’t think the action will be affected. However, the strings on a classical are further apart on the wider neck which will affect your ability to hold the strings down particularly with bar chords. If the guitar has a pickup, it will be designed for nylon strings. The pickup will probably pick up the sound from the steel
