scale length

cactus bum · Post by **cactus bum** » Fri Apr 10, 2009 9:00 am

Howdy, I am wondering if it is feasable to change the scale length of the Martin Size 5 Terz guitar I am starting to a longer scale length. I have a Baby Taylor that has a scale length of 22.75" with 14 frets to the body. I like the size of the Baby well enough but want a better sound , and this is my motive for building the Terz. The plans for the Martin specify a 21.375" scale length with 12 frets to the body. I am doing more and more playing up the neck and want to easily barr the 10th fret. The actual difference in the length of the neck of the two guitars from the nut to the body is something like 1 7/8". I am actually building two Terz, one true to plans and appearance, and the other more experimental.

My question is will I be sorry if I put the neck design of my Baby Taylor on the body of the Terz? By the way, the body size of the Baby and the Terz are almost identical. I appreciate any input you experts have for me. I am just beginning glue-up of the top and bottom so there is sufficient time for making a change. Cactus

Bob Connor · Post by **Bob Connor** » Fri Apr 10, 2009 9:15 am

cactus bum wrote: My question is will I be sorry if I put the neck design of my Baby Taylor on the body of the Terz?

I don't think so.

Draw up a plan of your bracing and make sure that the bridge wings are still over the X-brace and you should be fine.

The 12 fret will have the bridge placed further down the body so by replacing it with a longer 14 fret neck it may well remain in the same place.

Kim · Post by **Kim** » Fri Apr 10, 2009 9:21 am

The main thing to watch in changing scale length is where the wings of your bridge will be in relation to the supporting braces. If you have an 'X' brace top, the wings of the bridge will need to be supported by the lower legs of the X. If you start the bracing with this in mind you can change the scale length of the instrument to what you like by simply moving the X up or down to accommodate.

Cheers

Kim

jeffhigh · Post by **jeffhigh** » Fri Apr 10, 2009 9:56 am

By my calculations at the moment the bridge saddle will be 10.69" from the body/neck junction (plus compensation.
Going to the slightly longer scale and 14 fret will give 10.13".
This (0.56")is a pretty significant distance.
You may need to relocate soundhole, Xbrace and certainly bridgeplate

Hesh1956 · Post by **Hesh1956** » Fri Apr 10, 2009 9:58 am

And, in addition to what Bob and Kim said be sure, when you draw up the plans make sure that your bridge plate is under the bridge. I like to see about 1/8" of overhang for the plate beyond the foot print of the bridge but that's just me. The real point here is that when changing scale lengths besides the wings being over the X legs the bridge plate needs to be under the bridge.

Surprisingly there are so very many ways to change things around with the bracing of a guitar and still have it sound great.

Good luck.

cactus bum · Post by **cactus bum** » Tue Apr 14, 2009 2:00 am

Thank you for answering me Bob and Kim. I will heed your advice. Jeffhigh and Hesh, thanks also. Your advice is so logical I should be able to make it work, I think Ciao Cactus Hesh, are you comfortably working in your new shop now? Like a kid in a candy factory?

pat foster · Post by **pat foster** » Tue Apr 14, 2009 12:18 pm

If I might jump in here.

Sounds like the makings of a sweet little guitar.

An increase in scale length of almost two inches means that the nut would go north one 3/4" or so, and the bridge will go south 3/4" or so too. On the Martin size 5 Terz, the bridge is pretty low on the lower bout, and I'd be concerned that moving it further south another 3/4" could get it close enough to the tail that it might affect the tone. If it were me, I'd consider making it a 13-fret or even 14-fretter, which would make those barre chords at the tenth fret easier to do. Rearrange your bracing and soundhole around where the bridge needs to go. That's your "ground zero".

Pat

Allen · Post by **Allen** » Tue Apr 14, 2009 5:19 pm

Hey Michael, as you know, I just love the little Size 5. Please post pictures of your progress if possible. I'm so keen to start on another. I'd love to see what you end up doing with these two.

cactus bum · Post by **cactus bum** » Wed Apr 15, 2009 1:15 am

Pat, thanks for the exacting answer. I need now to get a plan put to paper. Lucky for me I have the Baby to take measurements from. I will get back to this thread once I have figured it out.

Allen, YES I plan to begin a "first build" thread. I have ben taking photos and will begin the thread soon.

cactus bum · Post by **cactus bum** » Mon Apr 27, 2009 3:34 am

Well, I got my pencil out and on paper I moved the X braces and the sound hole up 5/32â€

Allen · Post by **Allen** » Mon Apr 27, 2009 5:40 am

I like to have the X-brace cross the footprint of the bridge so it enters at the top of the bridge, and exits out the sides. Not the back

Do not notch the bridge plate under the X-brace, nor any of the tone bars or finger braces. The bridge plate in only in between the lower legs of the X-brace, not extended outside of them.

You need to build so the bridge will be able to vibrate front to back when a string is struck. Not so stiff that it locks the top up and inhibits this. If the X-braces exit the back of the bridge, then it's going to have a heck of a time trying to move all that wood in the X-braces and excite the lower bout.

As far as moving all the other tone bars and finger braces, this is up to debate. You'll see all kinds of variations on these. This is going to affect the tone of the instrument, and part of your individual style

cactus bum · Post by **cactus bum** » Mon Apr 27, 2009 10:43 am

Allen, I knew you would be the first to answer. You are an early riser.

I could move the X brace up a bit, but I would have to do away with the lower soundhole brace. I think the X moving up would make the lower soundhole brace redundent anyway, as with many guitar designs there isn't even a lower soundhole brace. Allen, your set of plans for the Trez is by a different person, I think. Is there a lower soundhole brace in your plans? I confess I have never held a Martin size 5 Terz.

My next step will be to move the X brace up, on paper, and see if the X exits the bridge on the side, as you suggest. I will get back to you on that. Thanks Allen, very much, for your continued support and input.

CIAO, Cactus

Allen · Post by **Allen** » Mon Apr 27, 2009 5:12 pm

My plans show a sound hole reinforcement all the way around, but for most of my guitars I've ended up forward shifting the X-braces and have not bothered with the one running parallel to the Upper Transverse Brace.

Looking back at the top on this one, there was probably a bit of room to install that brace, but the top has not shown any sign of deforming there yet, and it's been strung up for a year. So should be good for a while yet.

Here is a couple of shots of the top bracing on mine.

cactus bum · Post by **cactus bum** » Tue Apr 28, 2009 2:30 am

Thanks Allen, A pic is worth a thousand words. Your craftsmanship is something to aspire to.
It seems I can move the X brace up another 3/8" to 1/2" and make the X braces come out the side of the bridge. Will this adversely affect the bracing strength of the lower bout in that the lower portion of the X braces are now shifted farther up toward the waist? Should I compensate in some way by changing the position of the finger braces or the position of the lower face brace?
I like how the sound hole finger braces go through the upper transverse brace. Mine do not, but it makes sense to me. Maybe I should be doing this.
Are your finger braces tucked under the X braces a little bit?
How thick is your bridge plate? What material? Looks like Macasar Ebony a bit. I have some hard maple I can use.
Hard to see, but it looks like a small wood patch over the apex of the X braces. Same material as the X brace itself, I assume. Cumpiano uses linen, Kinkead uses spruce. I like the idea of spruce myself.
Also, what material are the side struts made from? What dimension?
Sorry to ask so many questions. My learning curve is like a shuttle launch. So much to grasp, I love it!
Save Tibet Indeed (your message inside this guitar). I have been in the presence of HH the Dalai Lama twice. His countenance was amazing. He radiated serenity, wisdom, strength, love. Amazing. Shouldn't get off on tangents, I know. Cheers, Cactus

Allen · Post by **Allen** » Tue Apr 28, 2009 5:37 am

On this one I placed the finger braces so that they meet the lower X-brace where the top corners of the bridge would be. Lower tone bar was just placed where I thought it looked appropriate.

The side reinforceents are bias tape that I get from the local fabric shop. Comes in all kinds of colors, so you can match most woods, or find something that compliments. It's applied with hide glue much like doing a fiberglass repair if that is familiar to you

Bridge patch is 2.5mm thick Queensland Walnut. I've got heaps of it, and it's very hard, and pings nicely when dropped on the floor, so it's what I've been using for bridge plates.

I cap all my X-braces with the wood that they are made from. The braces on this guitar are Western Red Cedar, as is the top.

Finger braces are not tucked under X-brace

cactus bum · Post by **cactus bum** » Tue Apr 28, 2009 8:43 am

Thank you Allen. I show in the photo the new plan I have drawn which moves the X braces up enough to make them come out the side of the bridge, instead of the bottom. My draftsmanship is not good, and the measurements might be off up to 1/4", but as a rough plan is this looking like it is feasible?

Allen, Because It doesn't seem appropriate to place a copyrighted plan on this public forum I am e-mailing you a photo of it so you can see the before and after plans.

By the way, I extended the soundhole braces up under the upper transverse brace and through to the head block. I also scrapped the lower soundhole brace. Do these braces get tucked under either the X brace or the head block? Should I put in a wee stubby lower soundhole brace?

Anyone like to chime in? Thanks Cactus

Allen · Post by **Allen** » Tue Apr 28, 2009 4:30 pm

On those 2 braces I did tuck them into the X-brace, as I was wanting to lock this area up as much as I could. It was my first go at an adjustable neck and I hoped by doing this, I'd stiffen the neck block area up.

It won't hurt to through in a little soundhole brace if it makes you sleep better at night.

As far as I can see, these modifications that you've made are not going to screw anything up, and should be good to build with.

cactus bum · Post by **cactus bum** » Wed Apr 29, 2009 1:59 am

Thanks Allen and all of you. Guess I'm good to go now. When my friend with the drum sander gets time I will have thicknessed tops, sides and backs ready to build. Cheers, Cactus

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