Official Luthiers Forum!

I would like to build one of these which currently has a scale length of 24.625
with a longer scale length of 25.4 or something close
I understand I will probably lose a fret and have to move the bridge but was wondering if there might be any other reasons why this would be a bad idea?

You have to lay the neck and bracing relationship out. You will likely loose a fret or more because of the sound hole location. This is one mark aginst making the alteration. and Depending on brace location, X brace splay and bridge plate size and location you may or may not be able to move the bridge position, but you dont know till you lay it all out on paper. Also ther is a slightly differnt saddle compensation (eg;saddle slot slatn angle) from one scale to the next for it to be set ideally. To make it look original with no trace of the change and if bracing and all allows you will pretty much have to take at least the top back to the white and refinish it.

those four things would make me want to build a new at the desired scall so that I could control all geomatry in advance raather than try to alter.

Steve-
Your post sounds like you are planning a new build ?
As Michael said, you will need to just draw it out.
One possibility would be to join the body/neck at the 15th fret, but that might be a bit unconventional.

Cheers
John

Steve:

You are adding roughly an inch. I would give up the extra fret or two, but there are a few folks using other that a 12th or 14th fret joint. John Mayes uses the 13th fret on some models.

With the variations of sound holes and side vents being used today, one might consider relocating or redesigning the sound hole to allow additional frets, maybe just on the high strings?

I intend to use a longer scale on an OM style soon and still have all this to work out. Lets us know what you decide.

Danny R. Little

You are adding .775" to the scale length.
If you still join the neck to the body at the 14th fret then about .37" or so of this will be added between bridge and body joint so this is how much you will have to move the bridge back.
If you maintain the soundhole position you may lose a fret unless you let the board overhang a bit

Start with a drawing with a centre line. Once you have the nut and the saddle location, draw the guitar body from the 14th fret. The rest (bracing, bridgeplate, soundhole) will fall into place naturally. No need to join at any other fret than the 14th, the difference with the short scale will be minimal, and it is much less than adding a fret: it is stretching both ways from the 14th fret (or the 12th).

_________________
Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/