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OK...I have a 650 neck and a fan fret layout from 640-660. My thoughts were to split the 12th fret diagonal on the body....so 12th fret treble side doesn't layout directly on the body. This way my bridge and soundhole location remains the same as my 650 hauser plans. Is this not Kosher...or does the fan fret allow for unconformity in the luthier world.
The odd one,
Kent

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Wood Creations by Kent A. Bailey
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I have done a few of these but on electric basses so the neck to body relationship had different considerations. You may have to release yourself from the idea that the 12th fret must meet the body at one string or another. No matter what, it will cross the body and that will have to do.

There are many variables at play. For instance, if you start with your nut at 90 degrees to the center line of the guitar you will have a very different answer than if you have chosen the 7th fret to be at 90. The fan angles will change making for all kinds of mathematical fun. Without more info I can't comment on your specific issues but here is some basic stuff.

If you use the center line of the neck as your foundation instead of the bass or treble sides it makes things simpler to discuss. Your average scale length is 650 which is the same as the distance from nut to center of saddle between the third and fourth strings (ignore compensation for the moment). In a standard configuration the nut and saddle are parallel to this line. Now imagine a pivot point at the center of each. Leave the nut at 90 degrees and increase the bass scale by 10mm and the treble decreases the same. Draw in the 7th fret (arbitrary choice) and "lock" it to the two outer strings. Move it to 90 and the nut on the bass side moves away from the body and the treble does the opposite.

If your neck is already cut to 650 scale then you are limited as to how you can move the nut end. You can not make it longer unless you go buy that expensive board stretcher you can't afford. If you choose any fret other than the nut to be at 90 degrees the pivot point that was on the center of the nut will need to move towards the body. This will change where the 12th meets the body as well as the center of the saddle as well as the angle of the saddle.

In short I would lay out the bridge location and my nut location and let the fret meet the body as it will.

Fun stuff.

Sorry about being so vague but I don't know enough about your particular instrument to be more specific.

Greg N

Thanks Greg,
I concluded that my current 650 neck with my 640/660 fan layout would bring the 12th. fret at the center of the fingerboard and the front of the body. I just didn't know if the Luthiers Proper placement of the fret at the 12th. SHOULD be on the treble side on a fan fret. I'm sorta stuck with where it goes unless I change the scale length layout again.
Kent

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Wood Creations by Kent A. Bailey
EXCELLENCE IN SCULPTURE, CARVING, LUTHIER, ARCHITECTURAL MILLWORK AND DESIGN

http://www.kabart.com

http://www.paul-galbraith.com/engl/8string.htm

Here is a link to Paul Galbraith's 8-string classical. I think that once you decide to make a non-standard classical for your comfort in playing, then you should not be concerned with trying to match anything to other than your comfort.

Kent,

I'd love to know what a Luthier's Proper placement is

What Greg said. Basically you can do what you want with multi-scales (they aren't "fan frets" unless the fretboard has no taper in it ) and you don't have to have any frets perpendicular to the centre line of the fingerboard if you don't want to and where/how they cross the body join is up to you.

Builders usually choose one fret to be orthogonal but that one varies from builder to builder and is determined by the differences in scale and playability considerations at the nut and bracing considerations at the bridge. If your body neck join is the 12th fret you could chosse this to be orthoganal and it will cross the body "there normally" I keep the ninth fret orthogonal and have the fret that joins the body meet in the middle of the fretboard.

Get some pieces of cardboard, one 640mm long one 660mm long, one nut length and the other string width at the saddle and join them with split pins that can pivot as the fretboard (plus the strings to the bridge). Then join them with another piece that is half way along each long edge with split pins to be your 12th fret. You can then play with this on your neck body layout seeing what works best and how the 12th fret crosses.

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Great word.

The decision as to which fret is perpendicular has everything to do with playability. Putting it at the 12 can make playing the first few frets uncomfortable as the "back angle" would be significant. Putting it at the nut can make playing up the neck difficult to play. I suggest several templates be drawn and "from the gut" analysis done before committing to any fan.

Greg N

Yes - I like to call that fret "the perp".

Classical players - as many electric players - like to use most of the neck, and so this makes #7 a good choice for the "perp". First position is not a mangled mess, and upper frets flow more naturally into a relaxed hand position.

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The member formerly known as erikbojerik....

I've played classical for 40+ tears and have ALWAYS had problems with hand arm flexibility and getting my hand twisted to the upper strings and perform without complete body distortion..(must be those old/tired/thick woodcarver hands). I think I will much prefer a PERP nut...and progressive angle from there up. I may reduce the base side scale slightly to keep the angle from getting to severe at the 12th. The layout I currently have seems to be comfortable for my hands. I have an extra long bridge blank and bone to manage the angle at the saddle. I may need to get a little creative with top bracing to counter the angle pull and possible top twisting. Maybe????
Thanks everyone.
Kent

_________________
Wood Creations by Kent A. Bailey
EXCELLENCE IN SCULPTURE, CARVING, LUTHIER, ARCHITECTURAL MILLWORK AND DESIGN

http://www.kabart.com