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Scarf joint and fanned frets - not friends
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Author:  lactose [ Fri Apr 03, 2015 8:48 pm ]
Post subject:  Scarf joint and fanned frets - not friends
On some of the fanned fret guitars I see, the line formed by the change in angle from the fret board to the headstock is not perpendicular to the neck. It is tilted so the nut sits on that line at the proper angle for the fanning. I did a little experiment. I thought I would just introduce the angle on the x plane as well the y plane angle for the scarf. But it looks like it is more complicated than that. (I have never experienced that in guitar building).

So unless I want the headstock sitting out there at a weird angle (who knows, I might...) I think what the pros do is make the initial scarf cut, throw away the little piece, then with another piece of wood, cut it again with the x plane angle reversed. Then the head stock piece lines up correctly.

Can anyone confirm ?
Thanks.


Image
Author:  DennisK [ Fri Apr 03, 2015 9:06 pm ]
Post subject:  Re: Scarf joint and fanned frets - not friends
Cut the scarf square like normal. The headstock piece needs to be fairly thick. The 1x3" neck blanks that Hibdon and similar places sell are good. Then taper the shaft piece (I do 3/4" at the heel to 5/8" at the nut), glue the scarf, and mark your angled nut line on the neck. I make the fingerboard first, so I can drill the position pins for it at this point and trace the nut line from it. Then plane the headstock starting from the treble side, to tilt the surface until the shaft to headstock transition matches your marked nut line. Should look like this:
Attachment:
CFSlots.jpg


The headstock will be fat on the bass side, but after thinning it down from the back it will be a nice constant thickness, tilted surface with the scarf joint glue line nicely placed in the shaft to headstock transition area.
Attachment:
HeadstockBack.jpg
Author:  lactose [ Fri Apr 03, 2015 9:30 pm ]
Post subject:  Re: Scarf joint and fanned frets - not friends
Awesome thanks. I don't think I would have understood without the pics. Are those carbon fiber slots next to the truss rod ? That headstock transition is beautiful. Lately I am making the neck asymmetrical on the back, so thick on the bass side would work out great.
Author:  DennisK [ Fri Apr 03, 2015 9:54 pm ]
Post subject:  Re: Scarf joint and fanned frets - not friends
Yep, that's a butternut neck, which is a little weak for steel strings on its own.

And yeah, pictures really do make it easier to explain things :)
Author:  Pat Hawley [ Sat Apr 04, 2015 8:20 am ]
Post subject:  Re: Scarf joint and fanned frets - not friends
Most likely starting with 1" thick neck blanks will be fine however it doesn't hurt to be aware that the thickness you need is a function of the angle of your nut. For example, I am currently making a fan fret guitar with 23" - 26" scales (yes, I know this is a big difference in scales), 7th fret perpendicular and the nut angle is such that the 1" thick neck blank stock is not quite thick enough. When planed down, the head gets down to only 1 cm thick on the treble side. Don't ask me how I know this.

After the fact it was obvious to me that you can easily draw out it on paper first to determine if you have enough thickness. Draw out a side profile of your neck blank with the scarf joint completed. From where the scarf joint starts back up the neck (towards the higher fret end) the distance required for the total nut angle and make a mark. From that mark draw a line to the end of the head and parallel with the top (or bottom) lines of the head i.e. draw the line to which you would be planing to. Now you can see the amount of material that will be left under the line and decide if that will still be thick enough at its thinnest point.

Pat
Author:  Pmaj7 [ Sun Apr 05, 2015 2:52 am ]
Post subject:  Re: Scarf joint and fanned frets - not friends
DennisK wrote:
Attachment:
HeadstockBack.jpg
Dennis, nice clean looking back of headstock. Is it all flat?

Also, when making a slanted nut, does the head end up wedged shaped? If so, do you end up with diff tuner height?
Author:  DennisK [ Sun Apr 05, 2015 1:23 pm ]
Post subject:  Re: Scarf joint and fanned frets - not friends
pat macaluso wrote:
Dennis, nice clean looking back of headstock. Is it all flat?

Also, when making a slanted nut, does the head end up wedged shaped? If so, do you end up with diff tuner height?

It's only wedge shaped for a short time during the shaping of it, before having the thickness adjusted by removing wood from the back.

And actually, that particular one is concave over a lot of the back, and the thickness tapers some along the length, but is mostly symmetrical in the side to side direction. The tuners are planetary gear pegs, so the back surface of the headstock doesn't have any effect on the height of the posts above the face. For normal tuners, it would be a bit thicker at the end, and with the concave area confined to below the first tuners. This one isn't fan fret, but shows the surface topology nicely:
Attachment:
NeckCarved.jpg


The front and back surfaces pretty much have to be coplanar for normal tuners, or the grommets won't be angled the same as the posts. Otherwise I'd taper all my headstocks, because I think it looks more elegant :)
Author:  lactose [ Sun Apr 05, 2015 9:40 pm ]
Post subject:  Re: Scarf joint and fanned frets - not friends
Pat, I hope to see a pic when you are done. I have wanted to try a two inch fan, because I like the look. But I think 1.5 inches is as far as I want to go, as it makes a low F bar chord a little difficult to manage. Of course the whole fret layout can be 'rotated' so that you have less angle on the top (nut) and more on the bottom.

So, with the way you guys start out with a straight scarf joint and plane it, does the headstock face end up a little twisted ?
Author:  DennisK [ Sun Apr 05, 2015 11:53 pm ]
Post subject:  Re: Scarf joint and fanned frets - not friends
lactose wrote:
So, with the way you guys start out with a straight scarf joint and plane it, does the headstock face end up a little twisted ?

The headstock itself is flat (not twisted), but the plane is "rolled" relative to the neck surface plane. The angled nut line is the intersection between the two planes, and its angle is caused by the roll. However, it is also dependent on the pitch angle of the headstock. If you use a 17 degree pitch, you'll need more roll (and therefore more extra thickness to plane away) than if you use a 13 degree pitch.

Pat makes a good point that a 1" neck blank may not be enough thickness if you're doing extreme scale differences. I've never gone over 3/4" difference, and doubt I'll ever go to even 1.5". Pat's 3" is crazy :lol: Hope whoever it's for likes it.

I think it would be possible to reduce the amount of thickness needed, by tilting the glue surface on the headstock piece before gluing it... like your idea in the first post.
Author:  Pat Hawley [ Mon Apr 06, 2015 9:04 pm ]
Post subject:  Re: Scarf joint and fanned frets - not friends
I will post a picture of this guitar when it is done since it is somewhat unusual. The client wants a guitar that can be tuned in 5ths, hence the extreme difference in scale lengths. I did an 8 string with the same degree of fanning (over 8 strings the difference in scales was 4") and its owner assures me that he and anyone else that has tried the guitar did not have any difficulties with the fanned frets.

Pat
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