Another option is to take it to music store and have them measure the diameter of the strings on the dulcimer using a micrometer. You can then purchase the same gauge strings.
"The dulcimer sings a sweet song."
Strothers String Calculator: http://www.strothers.com/string_choice.html
Diameters of the strings will vary depending on the VSL and the Open tuning notes you want. VSL is the distance between nut and bridge. DAA will be slightly different that DAd, CGG vs CGc the same. A given set of strings will let you tune up or down two steps before getting too floppy or starting to break.
Awesome dulcimer. I have had good luck with Strother's string gauge calculator. They do show a bit light at times so you may want to go one or two numbers heavier.
Juststring.com is a good source of strings if you want to purchase singles and make up your own sets.
I recently purchased a beautiful Bill Davis 1960’s hourglass four string dulcimer including the original felt bag.
I would like to replace the strings -does anyone have any recommendations on the diameter of the strings I should use and also the manufacturer of strings that you would recommend?
Thank you for your replies.