kingfisher

Thanks Wes, don't fancy head end, but those long allen keys may solve the problem.

I am currently building my first acoustic, a Selmer Django Reinhardt copy (the one with the small oval soundhole). I am not looking for full authenticity here, and I wish to fit an adjustable truss rod, one of those threaded rod in an aluminium channel things.

How do I do this? If I fit the rod to the length of the neck, it will be nearly impossible to adjust (small soundhole, long way from neck)

Should I make a longer neck that reaches inside the body nearer to the soundhole or what? Or should I look round for a long allen key?

Anybody done this?

my babbling has never stopped anyone from doing what they had intended to do anyway...

Mine neither. (fortunately)

Actually it is not expensive and actually it does dry clear.

It is waterproof though.- (why is that a bad thing?)

And as regards tuners, in an ideal world I would like one with a readout of the actual cycles per second, but I don't know if anyone makes (an affordable) one.

Also, maybe we are a bit at cross purposes here. Are the Earvana and Feiten systems more designed to give a better compromise for chords? (we all know if you tune to a perfect sounding open E chord at the bottom of the neck, and then play a C chord, again in the first position, the C chord sounds way out).

This would explain the Satriani thing, depends on what you are playing - if you were only playing E shapes up and down the neck -who cares about C shapes?

The "Kingfisher method" (if I may humbly use that term) is more about putting the frets in a better place for up and down the board on a single string.

Now, moving the frets about as I propose will certainly affect the chord thing - but how I don't know. - is this E/C thing better or worse on a Gibson or a Fender? - how should you tune the guitar (fifth fret, octaves or WHY).

It is my untested and unsubstantiated belief, with no evidence whatsoever, that the chord thing will be affected in a positive, good way.

Thanks for that Doug - very interesting.

I was talking about this

Bleh, I wait for the day when a pill is invented that makes my dissonant out-of-time playing music for the educated ear. Balls t'yer compensation lad.

Good argument, well presented.

Using 17.818 on a 650 mm scale I get 324.989 = 325 - 0.011

Using 17.817 on a 650 mm scale I get 325.002 = 325 + 0.002

I stand corrected on that point.

John.

As for the Earvana stuff, that is irrelevant to the argument. My theory ONLY relates to the octaves. Earvana assumes perfect octaves and is dealing with the stuff inbetween.

!7.817(ish) will not give you perfect octaves, so presumably the Earvana stuff is a non starter without you sort that first.

What do you mean "rusty old door hinge"

The tailpiece is a repurposed ferrous artefact covered with a copper/zinc alloy, originally designed for variation of angular placement relative to a entrance frame.

When I get a minute (too busy worrying about Rooney's ankle at the moment), I will redo the experiment with different string gauges. I purposely used the most commonly used top E gauge, and set the "action" to what I would regard as pretty damned good at the 12 fret.

We already know that thicker strings behave differently, - your bridge is never straight, - but on the other hand when playing in the oxygen thin atmosphere of the top of the neck, we tend to be on the top three strings - (ever noticed how the tuning up there is very flat on the bottom three strings).

Gibson may have optimised the number for thicker strings - hence our disparity.

One thing I am convinced of - if you use the mathematically pure 17.818 (17.817 if you are Jewish) calculation - your instrument will NOT be in tune

Sadly I am afraid this may be a leap too far for some (even with the Gibson connection) and wrongly fretted guitars will still be made.

"The SG is 0.5 mm out" - sheet, I do my fret slots by hand with a saw - I dream of being 0.5 mm out.

And the crappy aluminium zinc parts bend over time. I know this.

Well they stick aeroplanes together with it - hence the name

Aerolite 306

I use it for neck and body laminations and find it to be the business, yet it is never mentioned on here?

Anybody else use it?

Wes, I agree with everything you say - but - (you knew there would be a "but" didn't you) - I am not looking for perfection because I don't think it exists, I am just trying to involve in the equation the fact that we have to press a string down to get any other note than open.

17.818 (or 17.817) takes no account of that at all, and I think it should. In fact my experiment (within experimental error) proves it should.

Do you think the neck profile needs some work?

interesting - do you have the string a 'normal' playing distance above the fret, i.e allowing for action

now you need to try the rest of the string set, different gauges, and maybe repeat with a few different brands to see if you can get some consistency in your results

I imagine you will get a different number with the different string gauges which i would expect to take away the mainstream use, although it would have potential for very specific set-ups

quickly shoved it in my spreadsheet next to the normal calculations

Yes normal action. This is why there are 2 frets on the slidy bit.

I too expect to get different results with different gauges, as we know the usual bridge compensation differs with gauge, probably a fan fret system could compensate for some of this. (ie a different divisor for top E and bottom E), but then we are getting into the realm of specialist instruments (harder to sell?). Consistency will be difficult without more accurate measuring equipment.

For now, as I say, I regard this as an improvement, invisible to the user, but tunes a bit better. If anyone would care to duplicate my experiment, please do and tell us your findings.

Do you think I should enter this instrument in guitar of the month? (this is a joke by the way for the humorously challenged.)

In the spirit of modern experimentation, I thought I would build a guitar to try see what happens -

As you can see, it is built from exotic timbers and is minimalist in form, having just one string (9 thou). The action is normal to low, and requires pressing the string down. (9 is our best selling gauge by the way)

First I set the bridge and nut 650mm apart (- they are both fixed), and tuned it to E, using the tuner in the picture.

Next I slid the movable frets to about halfway, and moved back and forth, until I hit E again. Nut to fret distance 323.8mm

Up another octave, nut to fret 486mm

Next I wrote a php program <a href="http://www.rockfactory.co.uk/fretcalculator.php">fret calculate</a>

results here -

Scale is 650mm

divisor is 17.91

1 36.2926 36.293

2 34.2662 70.559

3 32.3529 102.912

4 30.5465 133.458

5 28.841 162.299

6 27.2306 189.53

7 25.7102 215.24

8 24.2747 239.515

9 22.9193 262.434

10 21.6396 284.074

11 20.4314 304.505

12 19.2906 323.796

13 18.2135 342.009

14 17.1966 359.206

15 16.2364 375.442

16 15.3299 390.772

17 14.4739 405.246

18 13.6658 418.912

19 12.9027 431.815

20 12.1823 443.997

21 11.5021 455.499

22 10.8599 466.359

23 10.2535 476.612

24 9.681 486.294

As you can see a divisor of 17.91 seems to provide a fairly close match to my experimental results

Here is the php if anyone needs to check

“

<p>

<?php

$scale=650;

$divisor=17.91;

echo "Scale is " . $scale ."mm" . "<br /> <br />";

echo "divisor is " . $divisor . "<br /><br />";

for ($counter=1; $counter<25; $counter++)

{

$fret=$scale/$divisor;

$total=$total+$fret;

if ($counter==12)

print "<br />";

echo $counter . "&nbsp; &nbsp; &nbsp; &nbsp;";

print round($fret,4). "&nbsp; &nbsp; &nbsp; &nbsp;";

print round($total,3) . "<br />";

$scale=$scale-$fret;

}

?>

</p>

“

Loads of potential errors here, - new string, maybe more elastic than a used one - measuring equipment (cheap tuner and steel rule) a bit primitive - but nevertheless I will be going with this until convinced otherwise.

Still working on this when I have the time - will post if any more insights.

Anyway it seems that kingfisher has left the discussion and in any case talking is not going to solve anything.

No and yes in that order.

post removed till I think a bit more

Ha -No not grumpy at all - quite the reverse in fact - It was meant to be a lighthearted attempt at humour. probably lost in translation.

As I have stated more than once, I put this idea out for comment in the first place, all which have been gratefully received.

Thank you.

Having said that I still think if I put 25 into StewMacs calculator, and have to make it 25.2 to make it work, there is something wrong somewhere.

Thanks again to all for your input, at least it has got us thinking !

John

Just one more thing - was I right to use a no. 5 plane, or would it have been better to use a no.7?

Lots of tricky questions in this guitar thing.

OK then I'm wrong - and apparently Gibson are too. Brave man.

Firstly let me say that i put this out for discussion, i could be wrong on this. I usually am , but this is how I see it.

Suppose we fret a guitar, and first we need to work out the fret distances. OK, bit of maths. start with the scale length and divide by a number to find the first fret. Take away the first fret from the scale length and divide by the number again for second fret... and so on

So what number shall we divide by? lets say 10.

Oh dear the frets are way off, so we move the bridge a bit (a LOT) to try to cover up our error (i.e.using the divisor 10) No matter what we do , even if we get the 12th fret right , the rest of the frets are still wrong.

Bugger. Shoot the board and start again. lets try 15. not as bad but still nowhere near. Get the n0. 5 plane out again (board is getting a bit thin by now) and try 17.818. This is the number most of us use by the way.

Now it is still not quite right (we still have to move the bridge, but not by much, so we live with it.) What we need is a magic number to divide by that doesn't need bridge adjustment - that is the holy grail.

Of course due to string gauges , maybe different scale lengths, guitar or bass etc, this is not possible, but maybe we can get closer than the legendary 17.818. and get better intonation.

That's it.

I didn't know Gibson did this already, and my comment about "three sections" came from post #9 above.

And the original suggestion would only change the de facto over all scale length.

No It wouldn't. Thats the whole point.

The calculation would include the overall scale length. I am talking about the Gibson idea, as above, but rather than splitting into three sections, into 22 (or however many frets you have)

yeah but if you compensate this way then how do you compensate for different string gauges?

You don't. But at least you are in abetter position than no compensation at all.

Different strings ie E A D G B E need different compensation in the first place, all I am saying is that it gets you nearer to the ideal than "standard" fret spacing, so less movement of the bridge will be necessary.

I think my frets may be in the wrong place - and I think yours may be too!

First let me briefly introduce myself.

I have been on this board a good while, although I don’t post much. I have been making guitars for a good while longer (over 45 years) and have made around 30 instruments, plus innumerable repairs, refrets, etc. - so I am not exactly a beginner.

Back to fret placement. I have always calculated the fret positions using 1/17.818, which gives you the twelfth fret at half the scale length.

i.e. if the scale is 26”, then the octave fret comes at 13”. Seems logical, but then, when tuning,

the bridge has to move back a bit, to compensate for the string stretch when fretting. or to put it another way , the twelfth fret is not in the right place. So, it occurred to me, maybe rather than moving the bridge, which is all well and good for fret 12, but not for the other frets (the higher up the neck you go, the flatter the note), I should move the frets a bit in compensation.

This would be achieved by using a smaller divisor than 17.818 in the fret calculation. All the frets would then be moved by the correct amount. - well at least more correct than moving the bridge. The actual number is easily calculated by the way.

Am I on to something here?

I welcome your comments.

No problem.

Use a zero fret though.

I use an angle grinder with a sanding disk , finish off with sandpaper by hand. Quick and easy.