I converted a 6 string Regal Dobro to 7 strings a few years ago and thought it came out great. I suppose the neck could be wider allowing the string spacing at the nut to be a little wider, but its not bad and still allows for reasonable bar slants. It was all pretty easy with the conversion of the headstock being the only major surgery.
You could perform the next step to both sides of the headstock to end up with 8 tuners (as I did) or just 1 side for 7 tuners. After removing the old strip tuners I filled the middle of the 3 holes left on each side with epoxy. It just so happens that the outer 2 posts of a standard set of Mandolin 4 to a plank strip tuners line up very closely with the 2 outside holes left on each side of your headstock. Drilling 2 more holes on each side to match the two middle posts on each strip allows the new tuners to be mounted (I should mention here that unless your a pretty good craftsman you may end up with a bit of a sloppy fit with some of the posts in their holes, but it'll work just fine and I hope your not doing this to your pre war Dobro anyway).
I drilled a 7th hole & slot in the tailpiece, in the middle of and slightly behind the other 6 holes.
A single piece bridge insert can be fashioned (or you might try Paul Beard at Resophonic Outfitters or your local luthier)to replace the two halves that are in the slot in the spider bridge to begin with. The new one piece insert will allow you to spread the strings pretty wide, but will cover up the cone tension adjustment screw (you'll have to make that adjustment with the cover and strings off). I made a nut adapter for 7 strings that put the outside strings right on the edge of the fret board.
If anyone is interested in pictures of the guitar or has any questions feel free to email me. [This message was edited by Jeff Watson on 19 March 2002 at 06:32 PM.]
[This message was edited by Jeff Watson on 19 March 2002 at 06:36 PM.]
