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OM with 14 frets to body and 24.9" scale length?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=23268		 Page 1 of 2
Author:  Oskar Strådal [ Fri Jul 31, 2009 12:05 pm ]
Post subject:  OM with 14 frets to body and 24.9" scale length?
I will start by saying hello and extending a thanks to all of you for sharing your knowledge and contributing to a great community; thanks!

Now, I have been working on my first guitar for a couple of weeks now and i just realized that something hasn't(to say the least) gone according to plan. For some reason I have overlooked the fact that using a 24,9" scale and a 14fret to body neck would render the bridge rather close to the soundhole. duh So when marking out the bridge position before laying out the braces i got a surprise.
I might add that I have already shaped the neck and slotted and bound the fretboard. Anyhow, after spending the day looking through the archives and searching the forum I haven't gotten any wiser about how to procced with this.

I guess I'm wondering what you all think about 14fret / 24.9", how should one configure the bracings to match that onfiguration?Will it affect the sound, will it look strange?


Like anything else on this build it seems that I have to do everything at least twice, greater learning experience ey?
Any input would be apreciated, thanks in advance.
//Oskar
Author:  Mike Collins [ Fri Jul 31, 2009 12:26 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Oskar;
Welcome to the forum .
It may seem to be a bad situation but you can still make a very good guitar with that scale length.

Lay out the the bridge position on the top.
Using the 24.9 scale.
How many frets do plan on using?
Go with 18 -move the s.h. to 5mm from that fret .
You can make the f.b. follow the s.h. like on classicals or go straight across like on a Martin.
Next lay out where your bridge will be .
measure the distance between the bridge saddle and the s.h.
Divide that in half and that will be the center of your X brace.
Where they connect !
Then layout your braces .
You might end up with a 100 ,95-or 105 degree X .
Do not worry this will not affect sound as long as you carve the braces for the string tension you plan on using.

Then make the guitar!

Mike
Author:  Wayne Clark [ Fri Jul 31, 2009 12:41 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
I have done the same thing -- intended to make a short scale guitar and cut the soundhole for a long scale guitar. On my latest guitar I changed the scale from what was drawn (25.34 in) to 24.9 in. One thing I did to avoid forgetting some detail while building was to make a full-scale drawing (on paper) of the centerline of the guitar with the short scale. I marked the nut, 14th fret, end of fingerboard, soundhole, x-brace position and saddle position. That made it easier for me to keep track of what I was doing.
Author:  Oskar Strådal [ Fri Jul 31, 2009 1:01 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Thanks Mike, but I'm afraid I have already made the rosette and cut the soundboard pretty much to shape according to a 25.4" plan. Does the soundhole need to be moved?

Wayne, thats good advice, just wish i would have thought a few steps ahead. Seems that thats the theme of the build, I actually slotted for 22 slots and bound the fingerboard before realizing that it probably would cover half the soundhole. idunno

Guess i could flip the fingerboard over and make it a 25.4" instead...?
Author:  Corky Long [ Fri Jul 31, 2009 1:18 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Oskar, my friend - I think you just started your second guitar.... :roll: ;)

Having done that myself a couple of times (made perfectly good parts that don't fit for the guitar I'm currently building), I feel your pain. On the bright side, building is nothing if not addictive - you were going to build another one anyway, right??

Good luck.
Author:  Edward Taylor [ Fri Jul 31, 2009 1:24 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Why dont you buy a new fingerboard and slot it for the long scale and use this fingerboard for your next build?
Author:  Lars Rasmussen [ Fri Jul 31, 2009 2:02 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Tjenare Oskar,
nice to see another swede here! If I were you id get another fingerboard, supposing you havnt already cut the neck blank for a 24,9. Youre gonna put alot of hours into that guitar, and its never fun looking back and thinking 'if id only gone to the trouble then'... it may seem like a lot of work now, but i think its worth going the one step back. And, as previously stated, youll still have a nice 24.9 fingerboard for your next build :)

If you want to, i have some fingerboards slotted to 25.5 in my shop in sollentuna. Send me a pm if youre interested.

Allt gott,
Lars
Author:  Mike Collins [ Fri Jul 31, 2009 2:47 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Everyone here has given you great advise !
Save what you can for the guitar you wanted to make .
Keep the other parts for another guitar !
In other words -salvage what you can ,learn from this mistake and keep making guitars!!
WE ALL make mistakes !!!

Mike [:Y:]
Author:  Oskar Strådal [ Fri Jul 31, 2009 3:11 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Thanks everybody, really.

I was reading a couple of threads about mistakes people has made and it made me feel a little better. Eat Drink
I'm going to go through with the build just changing the fretboard to match the rest since thats what really was the problem, the neck blank is going to be a little tight but what the heck.

I was thinking of just flipping the fretboard over and cutting the new slots, would that have a big impact of the strength of the neck?

Lars, man tackar :) . I might just take you up on that if I can't solve this with the materials I have.

//Oskar
Author:  Jeff Highland [ Fri Jul 31, 2009 3:51 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Don't give up on what you have.
Set your bridgeplate position and bracing to match the scale length like Mike Collins suggested above. The difference in bridge position between 25.4 and 24.9 is only 5mm (from the neck joint) because most of the extra scale length happens in the neck.

Cut the end of the fretboard off to give you as much or as little overhang as you want
Going to a 25.4" fretboard is only going to INCREASE the overhang over the soundhole very slightly for the same number of frets
Author:  Oskar Strådal [ Sat Aug 01, 2009 4:36 am ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
If I understood Mr. Collins right he suggested moving the soundhole to match the shortscale. Is this really necessary if the difference in the bridge position's only 5mm?

Jeff, would you suggest going with the shortscale without moving the soundhole?

When I marked the bridgeposition on the top it looked kind of far off north, but seems strange that I would have picked upp on a 5mm difference. Myabe all of this i a non-issue..?

//Oskar
Author:  Jeff Highland [ Sat Aug 01, 2009 6:23 am ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Lars my last guitar was a OM 14 fret with 25.4" scale
My current build is an OM 14 fret with 24.9" scale
I left the soundhole in the same place, about 143mm from the body/ neck join to the centre of the hole.
I moved the bracing north about 5mm so it was in the same relationship to the bridge.
21 frets on the neck
what distance have you used to the soundhole? that is more relevant than the small effect of the change in scale length.
Check all your measurements again.
Jeff
Author:  Oskar Strådal [ Sat Aug 01, 2009 7:51 am ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Thanks for your help Jeff, but i do feel that i have to point out that contrary to popular beleif not all swedes are named Lars. ;)

The center of the soundhole is 149mm from the neck/body. The question is if this is an issue?

Since people have sugested that I redo and change things I got the impression that I really had to rethink everything. But the more i think about it it seems to me that it shouldn't be a problem?

//Oskar
Author:  Flori F. [ Sat Aug 01, 2009 11:15 am ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Oskar,

Welcome. As Jeff pointed out, going to a 25.4 scale will only increase the overhang. According to my calculations...

Distance from 14th fret to 20th fret 24.9 scale = 3.2 inches or 81.28mm.

Your soundhole center = 149mm from neck joint (/2) means that your soundhole edge will be 74.5mm from the neck joint.

a) If you go with 20 frets, you'll have almost 7mm overhang.

b) If you use 19 frets, you gain an extra 11.65 mm, more than enough.

I think a) and b) are your best options. I wouldn't got to a 25.4 scale. Do whatever you prefer!

Best,

Flori
Author:  Lars Stahl [ Sat Aug 01, 2009 11:41 am ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Quote:
i do feel that i have to point out that contrary to popular beleif not all swedes are named Lars.


Yes they are :D .

Sincerely Lars. :lol:
Author:  Jeff Highland [ Sat Aug 01, 2009 4:46 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Sorry bout the name mixup Oskar
Sounds like your soundhole is in the right positin wrt the 14th fret, just chose how much overhang suits you and cut your fretboard appropriately.
And double check your bridge position since you had concerns tha it looked too far north.
the formula (scale length) - (nut to 14th fret) + compensation will give you your distance from the body joint.
Author:  Mike Collins [ Sat Aug 01, 2009 4:53 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Oskar;
You do not need to move the s.h.
I just thought it may make your guitar more balanced to look at.

mike
Author:  Ricardo [ Sun Aug 02, 2009 12:30 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Do what I did - no sound hole problem and a louder guitar to boot. Of course there is a little more to it than that - just a thought.
Attachment:
000.jpg
Author:  Mike Collins [ Sun Aug 02, 2009 4:02 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Nice Ricardo !
But does it sound traditional?
Not that matters to me -but others may want to know .

Mike
Author:  Ricardo [ Sun Aug 02, 2009 4:58 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Mike, yes it does. I can only detect an increase in loudness with slightly less bass (being a smaller body) compared to my Taylor 414CE. It also has really good sustain.
Author:  Darryl Young [ Sun Aug 02, 2009 5:50 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Nice Ricardo. I've seen this design here a couple of times and I must admit it intrigues me. I'm surprised to hear it has less bass......What size are the soundholes? Two holes 2.828" diameter would give you the same area as one 4" diameter hole. I would have guessed moving the soundhole to this location would increase bass. Can one decrease the height of the intersection of the X brace if there is no hole in the middle to weaken the middle?
Author:  Ricardo [ Sun Aug 02, 2009 6:43 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Darryl, my sound holes are 2.75" in diameter. I guess one could change intersection of the X brace. It is more lightly braced than a traditional 000. I tried to guesstimate the bracing as best I could from a photo of a Grimes guitar.
Author:  Kevin Gallagher [ Mon Aug 03, 2009 11:16 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Oskar,
When using a 24.9" scale length on an OM shaped guitar, all you're actually doing is building a OOO.
The difference in the location of the bridge between the two is less than 1/4" and it will present no odd
or even easily noticeable appearance in the two guitars using the same soundhole location.

I recently taught a week long guitar building class in which the student decided to switch to the 24.9"
scale from the original 25.4" scale and there was no need to change anything on the top including the
soundhole and rosette location. The guitar came out great as we reworked the bracing placement to
accommodate the shorter scale length.

It was exceptionally loud and responsive when we played the guitar for the first time and it had that
great softer feel that the lower tension of the shorter scale provides.

Regards,
Kevin Gallagher/Omega Guitars
Author:  enalnitram [ Tue Aug 04, 2009 12:55 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
Been there, done that. I'm finishing up my first guitar right now.

viewtopic.php?f=10122&t=22708

I intentionally made it 24.9" scale and unintentionally placed the soundhole where it would be on a 25.4" scale. gaah consequently, all of my bracing is also 1/4" off. I've been told it will be fine. after much internal torment, I'm going for it, as the only alternative at this point, to "fix" it properly, is to rip the top off.

the placement of the bridge pin holes (so far, drilled for the low and high e) on my bridge plate looks like this:

http://photos-e.ak.fbcdn.net/hphotos-ak ... 0671_n.jpg

I'll have it strung up within a few weeks. if it explodes, or if it doesn't, either way, I'll post about it.

after I had discovered that this error ocurred, I spent some time in the "bracing library" thread at UMGF. one thing I noticed is that throughout the years, Martin bracing has sorta been all over the place. you will find both 000's and OM's that have the cross bracing barely nicking the edge of the bridge, and 000's and OM's that have the cross-bracing back-shifted so that the bridge is pretty dang close to the intersection of the "x." the variations are much more than even a mere 1/4". after I saw that, I wasn't so worried. it all "works," even though I much prefer prewar bracing to anything since. but I was still bummed out that I didn't get the intended situation that I was aiming for.

these are only our first guitars. i'm considering the intended, ideal situation to be a target for the next one...
Author:  SteveSmith [ Tue Aug 04, 2009 3:39 pm ]
Post subject:  Re: OM with 14 frets to body and 24.9" scale length?
I did something similar. 25.4" OM but I glued the fretboard on even with the headplate instead of leaving a 1/4" for the nut per the plan. Same result, my bridge moved 1/4" toward the soundhole. First thing I checked was the bridge plate but it looks ok - much like yours. I'm not real worried about it. I thought about trying to move the fretboard but with CF rods and all decided I'll do better on the next one. idunno
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