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Post by resotonic on May 5, 2020 23:05:42 GMT
So, if the scale length is the same on a 12 or 14 fret National, does that apply to original Dobro reso's as well?
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Post by Michael Messer on May 6, 2020 7:41:12 GMT
So, if the scale length is the same on a 12 or 14 fret National, does that apply to original Dobro reso's as well? In almost all Dobro resophonic guitars the scale length should be the same. Shine On Michael |
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Post by rbe on May 6, 2020 16:20:31 GMT
I think Michael is correct in his response for wood body Dobros. As for Nationals, the scale lengths did change on the 14-fret model. From 25" to 24.75". Fiddle-edge Dobros used both scale lengths, too. Might have been a Regal thing. Pretty much a post 1935 thing. As far as I am aware, California built instruments used the 25" scale. But after production began moving to Regal and Chicago, things started to change up. As far a wood-body Dobros go, the most likely place you might find the shorter scale would be on the Regal style, small-body models. I did check a Model 19 and 25, they were both 25". So there are two guitars that support the theory.
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Post by Deleted on May 7, 2020 8:55:18 GMT
As a side note, if you were to take the fretboard off a 12f neck, remove the large end fret (1" or so, then glue it back on), it will then fit the scale of a 14f guitar pretty accurately. Obviously the dot markers will be out of synch...
TT
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Post by bonzo on May 7, 2020 9:10:43 GMT
Might have a go at that later after I've finished washing up! Lol!
Best wishes and good health to you all, John
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Post by pete1951 on May 7, 2020 12:08:19 GMT
As a side note, if you were to take the fretboard off a 12f neck, remove the large end fret (1" or so, then glue it back on), it will then fit the scale of a 14f guitar pretty accurately. Obviously the dot markers will be out of synch... TT Not sure that would work in many cases. Fender did this with the Jaguar, which has a Strat/Tele scale minus the 1st fret. Pete |
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Post by rbe on May 7, 2020 18:06:24 GMT
TT,  If you cut the first 1" off a 25" scale fretboard (National), you end up with a 24" scale fretboard. If you cut to the first fret, you remove roughly 1 3/8". That leaves you with a 23 5/8" scale. The distance from the center of the cone to the body edge at the neck joint on a 14-fret National is around 11 1/2". If you want to make that a 12-fret neck joint, the scale length of that fretboard would be around 23". If you want to use a fretboard from a 12-fret National on a 14-fret National, don't do anything to it, they are both designed for a 25" scale board. |
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Post by Deleted on May 8, 2020 10:14:22 GMT
The 12f neck I have has a scale of 64.8cm (my MM 14f is 65.3cm by my measurements btw). If i was to remove the 1st fret of the fretboard (3.5cm) and move the fretboard up to the nut, the scale would then be 61.4cm (30.7 x2) - a difference of 3.9cm. Then, with the neck in place, the distance from 12th fret to saddle would be about 30.4. OK, I would be about 3mm out, but I could probably fix it in the mix  (e.g. use a zero fret). I don't have a national 12f neck to check with, so yeah, maybe it's just a fluke with the neck I have. I'm only considering this because I have a 12f neck and a 14f body which needs a new neck! TT |
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Post by Deleted on May 8, 2020 10:42:57 GMT
For clarity - if I removed the first fret and glued the fretboard back on the neck to the nut.
Measuring my MM 14f: the scale is 25 10/16" (according to my tape measure).
If I removed the first fret (1 7/16") and glued the fretboard back on the neck to the nut, the scale would end up being around 23 14/16".
Removing the first fret (1 7/16") wouldn't reduce the 25 10/16 scale by 1 7/16", it would reduce the scale by 1 12/16".
TT
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Post by tigercubt20 on May 8, 2020 14:14:47 GMT
For clarity - if I removed the first fret and glued the fretboard back on the neck to the nut. Measuring my MM 14f: the scale is 25 10/16" (according to my tape measure). If I removed the first fret (1 7/16") and glued the fretboard back on the neck to the nut, the scale would end up being around 23 14/16". Removing the first fret (1 7/16") wouldn't reduce the 25 10/16 scale by 1 7/16", it would reduce the scale by 1 12/16". TT the scale length defines the fret positions in equal temperament, by the twelth root of 2, 1.05946. all the frets have a slightly different ratio to each other, removing the first fret, means that all subsequent frets are now out of ratio.
swapping a 12 fret board with a 14 fret and vice/versa only works for the same scale lenght if all the fret are maintained in theyre correct ratios, removing the first fret means the second fret is now the first, but the second fret is now slightly out of position, and the discrepancy increases up the fret board, intonation wont be any help in this case. stay safe .
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Post by Deleted on May 8, 2020 16:15:14 GMT
Yes, that's why what I say works (in my case).
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Post by rbe on May 9, 2020 4:55:09 GMT
You're right, I must not have had my coffee yet when I wrote that comment.
You are dealing with some specs that work okay for what you are trying to do.
It's been a long day of breathing lacquer fumes, so my math might be wrong again, but, you have a fb that is 32.4cm to the 12th fret. Your body works with a scale that is 32.65cm to the 12th fret. Place your fb so that it is 32.4cm from the 12th fret to the saddle. Let the 14th fret fall where it may. Maybe around 3mm overhang. Doesn't that work?
Otherwise, you're going to end up with a short scale. I like short scales (24"), just never heard a reso with one. It is curious that a guitar that wants a longer scale to fit the spec is ending up with a much shorter scale to work.
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Post by resotonic on May 9, 2020 16:27:22 GMT
Those strings are gonna bounce!!
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(e.g. use a zero fret).