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Martin “O” Concert Questions

I want to build a 12-fret Martin O Concert sized guitar with a 23.5” scale length for my daughter. Questions I have are as follows:
•     What diameter soundhole should I use: and
•     How far from the heel should the soundhole be placed.

I’ve done some web surfing and I gather the original Martin O Concert 12 fret had a 1-7/8” nut, 24.9” scale and 20 frets.

John Hall is sending me the plans from the Martin factory for this model.
It is currently in route. I will let you know. Also, PM him and he could give
you the details
Andy

_________________
Andy Z.
http://www.lazydogguitars.com

Though I did send you the info I will post it here as others may also be interested in this.
   Holes are based on scale length and finger board length. Once you know what scale lenth you want to use you must plot the bracing locations on the top. With the fret locations figured you can plot where the end of your fingerboard will fall. IF you plan to reveal any of the rosette rings you will plan that in then find the holes center. 3 5/8 hole for the 0 size.
      I like to show the first ring of the rosette unless I am doing a 45 style then the first ring and part of the 2nd. I shorten the fret board for pearl .
Hope this helps
john hall

Remember, too, that as you shorten the scale, all else being equal, you will pull the bridge closer to the upper bout and off the "sweet spot" that the 12 fret, 24.9" scale O guitar enjoys (my Parlor guitars are built on the O-16 New Yorker layout, with modifications here and there).
In your proposed build, you'll be shortening the scale length 1.4" overall...half the length will be lost from fret 1 to 12, the other half from fret 12 to the saddle. So, your bridge placement will move approx .7" closer to the upper bout. That affects the soundhole placement and/or the splay of the X brace legs to clear the soundhole.

Do all this on paper/cardboard before you start cutting a soundhole or gluing braces...to see all the relationships.
I presume (reading into your post) you are using the short scale to accommodate your daughter's smaller hands/shorter fingers, so a narrower neck is also indicated. Plan ahead with the neck joint and you leave open the opportunity to (relatively easily) build a wider neck for her later in life after her hands/fingers reach their final size.

Gents -- thanks for your responses. I should have mentioned by daughter is 7-1/2 years of age and average size for her age.

Hank -- I was planning on laying everything out -- but (duh - me slapping forehead) hadn't thought of the effect of moving off the "sweet spot".

Probably best if I lay things out -- then ask questions.

A suggestion or two...do the 24.9 scale so that all the guitar neck/body relationships remain, including the sweet spot. Make the narrow neck but let your daughter start with a capo at the 2nd or 3rd fret if the "stretch" is too much for her in the first position. As her hand/fingers grow, gradually move back to the first position...probably in a couple years. Then, when she's all growed up, you can build her a regular(wider) neck and everything falls right in place...not to mention all the years of "playing in" the soundboard!

OR...go down to a Martin 1 or 2 size from the late 1800's and check their scale lengths. Those sizes would keep all the dimensions/relationships intact, and still have a really nice instrument for her to carry through life...including an "adult" neck width later as needed.

I agree with using a regular scale, and capo'ing for now if needed. At her age, her hands and fingers should be nearly full size and length, though they will not be very strong, yet. I friend's son was playing with us at our jams and band practice when he was 8, playing a dreadnought, no less... With it capo';d at the 2nd fret, and tuned a full step low, the strings will be nice and loose for her tender fingers, the position markers will still be in their correct places, and when the time coems to moce to a 'real' guitar, she need only take the capo off and tune it right up. Because, ths -is- going to be a real guitar.

I built a size 0 for my wife this fall. I had drawn up a plan using a '1929 0-18 that had crossed my path a couople years ago. I used the outline, but changed the bracing completely becasue I also changed the scale to my regular 25.5". The soundhole is 4-1/32". A very amazing little guitar that takes a back seat to nothing. Makes me wonder why we build large guitars...

here be

Anyhow, follow the above advice, as it was all sound, and do consider the regular 24.9" scale.

Mario,

What a great looking guitar. I'll bet Jen is ecstatic. I have been thinking of doing something along these lines for my grandson. That's probably a couple years off though. But at the rate I build it would probably take that long . Is that Mad or Braz? Is the top Addy? I was thinking about walnut.I already have neck that I screwed up last year when I made it 1 9/16" at the nut . Looking at your guitar made me think that something like that might be a good use for it.Jimmie D38749.9190625

[QUOTE=Mario] I built a size 0 for my wife this fall. I had drawn up a plan using a '1929 0-18 that had crossed my path a couople years ago. I used the outline, but changed the bracing completely becasue I also changed the scale to my regular 25.5". The soundhole is 4-1/32". A very amazing little guitar that takes a back seat to nothing. Makes me wonder why we build large guitars...here be[/QUOTE]
Mario - VERY nice guitar. I think no inlay on the neck is a very refined look. Nice work. Do you sign the inside of the guitar? What type of pen to ensure it's permanent?

All good feedback for me as well. I'm planning guitars for my wee ones. The regular length scale w/ capo and possibly narrower neck is great advice.

Is that Mad or Braz? Is the top Addy?

It's EIR and red spruce, yes. The red purfling lines were her idea, also, in case you're wondering...

My personal guitars, as well as both of Jen's, are 1-9/16" at the nut... Not a typo. 1.565"... Works great for kids, and adults. I have a client who's at least 280 pounds, was on his way to becoming a pro football player when he wrecked his knee, and has hands like gloves. His neck is 1-9/16" also. After playing mine and a friend's, it's what he wanted.

I do sign the center reinforcement(too cheap to have a stamp made up, <g> besides, this adds a personal touch). Jenny also signed this one, since it is her's. I use an archival ink pen. Available at better artists supply places.

Very nice guitar Mario, thanks for the links.

_________________
http://www.dickeyguitars.com

Nice guitar Mario!

Hank/Mario, rather than check in here last night -- I stubornly layed out a 23.5", 24" and yes a 24.9" (24.84") -- and I definitely see what you meant by the shorter scales missing the "sweet" spot. The shorter scales sure narrowed the "X" quite a bit.

Thanks for your suggestions.

Well, if you went 13 frets to the body, that would put the bridge and bracing
right about back in place.

_________________
Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Howard -- am I missing something? Guidance from Hank and Mario was to go with the 24.9" scale rather than the shorter 23.5 scale I was originally thinking of. Going with a shorter scale - 13th frets to the body would pull the bridge further towards the heel (or further away from the lower bout).

I believe Howard thought it was a 14 fret guitar, and not the 12 fretter that it already is.

At least, I hope that's what he thought <bg>

m'aussi Anthony Z38751.3830208333