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Changing Scale lengths from plans
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Author:  Andy Zimmerman [ Thu Oct 12, 2006 7:02 am ]
Post subject: 
A question. (Theoretical, but I have done it in the past)
Lets say a plan has a 24 scale length and you want to construct it at 24.9.

Do you....
A) Shift the X braces down, keeping the same angle to the correct bridge
plate position

B) Tighten the X brace angle therefore shifting the bridge plate to the
correct position.

C) Leave X braces alone, just move the bridge plate lower

D) Some other way to make the new scale length

Thanks
Author:  Wade Sylvester [ Thu Oct 12, 2006 7:10 am ]
Post subject: 
Andy,
Why not make the neck longer by .9 shifting the fret board and leave the rest as is?

Wade
Author:  Don Williams [ Thu Oct 12, 2006 7:11 am ]
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Hmmm....interesting question, because so many ways are possible, and almost nothing is "wrong".
The one thing I would not do is close up the X-brace. I'm a big believer in what angle I use. (I may be way off base there, but that's my preference and I'm sticking to it.)

Another option is making it a 15-fret, or if it's a 12-fret, making it a 13.

If it were me, I would probably shift the X to the correct position along with the bridge, and maybe move the soundhole slightly to help with the visual balance.

Don't forget, if you're talking a 14-fret instrument, the lion's share of the change will be in the neck...

My $0.02 worth. And it may not be worth that....
Author:  Andy Zimmerman [ Thu Oct 12, 2006 7:18 am ]
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I was thinking about a 12 fret. If you make the neck a bit longer, then
wouldnt the neck attach somewhere between 12 and 13???
Author:  Wade Sylvester [ Thu Oct 12, 2006 7:24 am ]
Post subject: 
Likely 13 and some change.
Andy, my last build is a 13 and 1/3 fret SJ and it barks loud. I should think you would like that.

Wade
Author:  arvey [ Thu Oct 12, 2006 7:24 am ]
Post subject: 
A, C or D, D being 13 fret neck. no matter what you do you will have to adjust it. And don't forget to move the Soundhole as well.
Author:  burbank [ Thu Oct 12, 2006 9:16 am ]
Post subject: 
Andy,

Seems to me the bridge would have to be moved if you changed the scale length. Otherwise, the body/neck joint would likely not fall at a fret position, though it's really only a cosmetic issue, as long as the bridge and X-brace were corret. I'd start with the 14th (or 12th or 13th) fret placed directly over the body/neck joint and measure from there to the nut position and build the neck to that. Then from the nut down to the bridge position, which would probably dictate what changes the X-brace would need. Bear in mind I've gone through this exercise on only three guitars, two to make sure the drawings were correct, the third to check out a basket case I was putting back together, but it was the only way that, to my mind, would really nail it.
Author:  Andy Zimmerman [ Thu Oct 12, 2006 9:35 am ]
Post subject: 
Pat
I was doing it as you suggested. Marking out the exact bridge position with
the new scale length. The question was mostly to figure out how to brace it
knowing the new correct position. How to change the bracing....angle....or
position etc.azimmer139002.7755787037
Author:  arvey [ Thu Oct 12, 2006 9:56 am ]
Post subject: 
I have a standard Bracing patern I use in a plexi glass template and simply line the soundhole up and lay the bracing out based on that. If the scale length changes so does the sound hole placement. I like to keep my bracing close to the sound hole so adjust everything as one. Likewise I use the same template for my 12 fret guitars and have the bracing moved down to correspond to the shifted soundhole. Does that make sence.
Author:  Andy Zimmerman [ Thu Oct 12, 2006 10:07 am ]
Post subject: 
Richard...Absolutely
That was what I did before. A big shift of everything as a unit.
The thing is my 0/parlor 24.9 doesn't have the best sound, and I am not
sure why. I don't have enough experience to diagnose the problem. I came
up with the design myself. I would eventually like to make another one, but
I would like to improved the tone.

In Feb I plan on taking E. Somogyi's voicing course. I am going to bring that
guitar for him to chew up and spit out and get his advice on how to make
another one better.
Author:  arvey [ Thu Oct 12, 2006 10:14 am ]
Post subject: 
I also build a size 5 with a 21.34" scale. For that my normal bracing pattern goes out the window and I have to use a pattern with a smaller X angle. and a little more space between the soundhome and X. At the same time so much goes into a new design. Voicing a guitar is so important. I have found just increasing the size of the soundhole or making it smaller can make a really big difference in the sound.
Author:  arvey [ Thu Oct 12, 2006 10:15 am ]
Post subject: 
I also build a size 5 with a 21.34" scale. For that my normal bracing pattern goes out the window and I have to use a pattern with a smaller X angle. and a little more space between the soundhome and X. At the same time so much goes into a new design. Voicing a guitar is so important. I have found just increasing the size of the soundhole or making it smaller can make a really big difference in the sound. Unfortunately I can't really explain how to tune the woods and frequencies while building even though I do it.
Author:  Steve Saville [ Thu Oct 12, 2006 10:44 am ]
Post subject: 
In your example, if you keep it a 14 fret model, the bridge would move back 0.45".
What would be wrong with leaving everything the same except moving the bridge plate back 0.45" and placing the bridge in the appropriate place for the scale length?
Author:  arvey [ Thu Oct 12, 2006 11:47 am ]
Post subject: 
A picture says a thousand words

As you can see I brace the soundhole and use finger braces for the fret board extension. I ave done L-00 without the Fingerboard support and had no problems but for the little extra work why not. Steve, there is no reason you can't just shift the bridge plate back as long as the bridge still sits on the arms of the X brace but it will mean your fretboard extension will be a little shorter and, IMHO look funny. It isn't an option for me anyway because if I did that the Bridge would not sit on the X brace properly. By the way, moving the bridge back and using a 25.4 scale length creats a guitar with volume and tone that will blow you away.arvey39002.8700810185
Author:  crazymanmichael [ Thu Oct 12, 2006 12:01 pm ]
Post subject: 
in any of the bridge/brace movement options keeping the braces away from the bridge pin holes and under the bridge wings and the plate under the bridge are the mandatories. otherwise you are free to experiment as you will. getting it optimal is a bit of a shell game.
Author:  Wade Sylvester [ Fri Oct 13, 2006 1:49 am ]
Post subject: 
Here is some food for thought.
Andy, if you really like your 24” scale plan, and it has the fret to body you are looking for, you could bump up the entire plans dimensions by 3.7%. This would roughly give you the 24.9 scale and you could see how everything is positioned at that size.
Granted, you may not want your body outline to increase that much but it will give you a reference for shifting things.
I use Adobe Illustrator sometimes to change scales and outlines of my designs. It seems to help me with these kinds of things.


Wade
Author:  Andy Zimmerman [ Fri Oct 13, 2006 3:10 am ]
Post subject: 
Thanks for all of the advice
I like the 24.9 scale length, but my first parlor was based on a 24 scale plan.
I went with the 24.9 and adapted. I am not happy with that instrument, so I
have been seeking out advice on how to change the design.
Author:  Steve Saville [ Fri Oct 13, 2006 3:15 am ]
Post subject: 
[QUOTE=azimmer1] I am not happy with that instrument, so I have been seeking out advice on how to change the design.[/QUOTE] May I ask specifically, why are you not happy with it?
Author:  Andy Zimmerman [ Fri Oct 13, 2006 3:34 am ]
Post subject: 
The tone is bit off. Some strings are a bit muddy. As a beginning player
and luthier, it is hard for me to describe what I don't like about it. I really
need an expert to play it and critique it. That is why I plan on bringing it to
E. Somogyi's course where he and many other experienced luthiers can
examine it.
Author:  Joe Beaver [ Fri Oct 13, 2006 8:18 am ]
Post subject: 
Assuming you don't want to re-draw your plans, the easiest way to change scales is get a slotted fingerboard of the scale you want. Lay it on the full scale plans so the 12 or 14 fret is at the body and mark where the fingerboard ends. Measure from the first or 12th fret, add compensation and mark where the new bridge goes. Now draw in the new soundhole and bridge locations and see where the bracing falls.

If you are going from a 24" to a 24.9 you will find the soundhole moves about .13" from the original and the bridge will move back about .4" You can adjust by moving the bracing pattern back about .4", or you can forward shift the braces by wherever..... As others have said just make sure you have proper clearance with the soundhole and bridge and the bracing.Joe Beaver39003.7240046296
Author:  Steve Saville [ Fri Oct 13, 2006 8:42 am ]
Post subject: 
[QUOTE=azimmer1] The tone is bit off. Some strings are a bit muddy.[/QUOTE] That could be from a saddle that does not fit well in the bridge. If the fit is not tight the energy loss can be dramatic. That's my first thought, perhaps it is something fairly simple like that or a saddle that is not tall enough.

BTW- When is the next Somogyi course?SteveS39003.7382523148
Author:  Andy Zimmerman [ Fri Oct 13, 2006 1:00 pm ]
Post subject: 
It is supposed to be the 4-10th of February but he hasn't advertised it yet
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