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Slotting for fan frets - Mike Dooling's method
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=48869
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Author:  Colin North [ Tue Jan 17, 2017 7:20 am ]
Post subject:  Slotting for fan frets - Mike Dooling's method

Planning on trying a fan fret using this relatively simple method
http://www.doolinguitars.com/articles/fannedfret/
He says the guides should be fixed to the edges of the tapered FB.
Normally I space the strings 3mm in from the edge of the FB at the nut and 4mm at the 12th fret.
I realise it's minimal, but...in theory should you account for the string path not being parallel to the FB edges?

Author:  johnparchem [ Tue Jan 17, 2017 10:39 am ]
Post subject:  Re: Slotting for fan frets - Mike Dooling's method

Give it to Mike Doolin to have such a simple but elegant solution. It seems the reusable guides would also allow you to adjust on each fretboard where the straight fret of the fan is.

Quote:
I realise it's minimal, but...in theory should you account for the string path not being parallel to the FB edges?


Interesting question, the strings really see a different scale length fret to fret? Doesn't the issue still exists even if you compensate the guides to the E string tapers as the strings themselves are not parallel to each other? So even if you adjusted the guides for the E string tapers they would not be parallel to any of the other strings.

Author:  Colin North [ Tue Jan 17, 2017 10:55 am ]
Post subject:  Re: Slotting for fan frets - Mike Dooling's method

I am wondering if it's any worse than a normally fretted board where the string paths diverge. Probably not.

Author:  johnparchem [ Tue Jan 17, 2017 11:16 am ]
Post subject:  Re: Slotting for fan frets - Mike Dooling's method

For fun I calculated how much length is lost (nut to 12 fret) with the extra 1 mm tilt. Assuming 325 mm nut to 12 fret I ended up with .0004 mm. Ignoring the 1 mm difference from the taper, because of the string angles there is a difference between normally fretted and fan fretted. On a normally fretted fretboard the strings cross all of the frets at the same angle so the outside (angled) strings see a properly scaled version of the original scale length. On a fan fret an individual string will see a different scale lengths fret to fret. The difference must not matter much as people do like fan fretted instruments.

Author:  DennisK [ Tue Jan 17, 2017 11:36 am ]
Post subject:  Re: Slotting for fan frets - Mike Dooling's method

Colin North wrote:
I am wondering if it's any worse than a normally fretted board where the string paths diverge. Probably not.

Slanting across parallel frets gives you a longer scale length, but the fret positions are still correct for the new scale.

Slanting across fanned frets at the wrong angle gives bad fret positions. Too complicated to explain exactly why.

Fortunately, if you lay out the high and low scales along the slanted string paths, then the fret positions for the other strings come out correctly as well, as long as the strings fan out evenly.

So as long as the board is tapered before using those templates, it should give "close enough" results. The fan will be less extreme than if you lay out the scales directly along the string paths (in other words, the low E scale will come out slightly shorter than advertised, and high E scale slightly longer), but the fret positions will still be good. Measure along the board edges rather than the string paths when positioning the bridge as well, to maintain consistency.

Author:  Tim Mullin [ Tue Jan 17, 2017 12:49 pm ]
Post subject:  Re: Slotting for fan frets - Mike Dooling's method

If you already have a table saw and a Stewmac slotting blade, you might look at the method I use:
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=47404&p=627420&hilit=fan+fret#p627420
You can make the scales and string setback anything you like, and different for every instrument. Tapered or not, doesn't matter. You simply print a reverse image of the fingerboard using Fretfind2, stick it on the bottom of your board as your guide. And much easier/faster than cutting slots by hand!
The online software for Fretfind2D is at
http://www.ekips.org/tools/guitar/fretfind2d/

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