Can I put nylon strings on a steel string instrument (and vice-versa)?
You will have numerous mechanical issues if you restring a guitar with meant for one style of guitar with the other. Nylon strings tend to be thicker so they may not thread through the nut and/or tuning gear very easily. Nylon string will have at least 30 lbs less tension on the neck, so the truss rod may not be able correct for the correct tension, and may not be able to return to correct tension if/when the guitar is restrung with steel strings. Steel string installed on a nylon string guitar can crack the body/neck as it was never meant to take the tension increase of steel strings.
