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#1
09-17-2023, 11:02 AM
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Intonation is far off but bridge and saddle measurements appear correct
Hi friends,
I've attached some photos of the bridge and saddle placement as well as the recommended intonation from the StewMac's intonator. (The tape measure in the photos was only used as a rough visual of whereabout the saddle placement were to go if I moved it up as far as it needs to to fix the 12th fret intonation. The tape measure was not used in placement of the bridge. The Saddlematic was used to place the bridge and saddle.) https://photos.app.goo.gl/fPPibCLSDjTJKh2h7 It is showing that the saddle needs to come forward by about .100. I measure this and used the saddlematic to try when building and measured it again and it looks correct. When I play the guitar, the intonation is definitely off and all strings play flat at the 12th fret. I'm happy to move the bridge to get this correct, but I would love to understand what I might have missed and how doubling the length from the 12th fret seems to have not led to proper location. Basically I would like to know so that I get this right for my next build! Thanks all. Appreciate any comments or questions. Last edited by jmurret; 09-18-2023 at 04:16 PM. 
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#2
09-17-2023, 01:24 PM
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I measure from the nut to the 12th fret and add about 0.075" to determine the distance from the 12th to the saddle at the first string. This is measured to the upper (soundhole) edge of the saddle, since that is the takeoff point for the first string.
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#3
09-17-2023, 03:58 PM
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I set the centre of my saddle on the 1st string at twice the distance of the nut face to centre of the 12th fret x 2 + 1/16" and add another 1/8" to the 6th string. That has been close enough for me on a 25" scale with Med Light strings. I use a steel rule to measure, not a tape measure.
My fret calculator shows 25.489" on first string for 25.4" scale String gauge, fret height, technique and action height can all play a part. Also, innacurate nut slots or not enough headstock angle, if allowing strings to move through the nut.
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#4
09-17-2023, 04:51 PM
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Quote:
Is what you hear flatter and flatter the higher up you fret - or less flat - or the same? Capo at the second fret and tune so each string it pitched correctly at that fret. Then what happens fretting further up the neck? Are the frets in the right locations. "The rule is sometimes called the "rule of 18". Basically, the position of the next fret, is the scale length, minus the displacement of the previous fret, divided by 18. It was close enough, and is still pretty close. Although the accepted number today is 17.817."
__________________
Derek Coombs Youtube -> Website -> Music -> Tabs Guitars by Mark Blanchard, Albert&Mueller, Paul Woolson, Collings, Composite Acoustics, and Derek Coombs "Reality is that which when you stop believing in it, doesn't go away." Woods hands pick by eye and ear
Made to one with pride and love To be that we hold so dear A voice from heavens above Last edited by rick-slo; 09-17-2023 at 05:35 PM. Reason: typo
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#5
09-17-2023, 04:52 PM
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Quote:
Read Fathand's comments.
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#6
09-17-2023, 06:52 PM
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a thought
I'd be putting that 'intonator' doodad back in the box. Too many cooks in the kitchen. I think there's a lot of ghosts being chased here.
I have had excellent results on five guitars (all with the same saddle thickness, so the Saddlematic doesn't need to be adjusted) using the Saddlematic on various scale lengths. I'd aligned my bridge and saddle with the saddlematic and a real luthier independently aligned the bridge and saddle using his preferred methods. Both techniques put the bridge in the same place. I think I can trust my tool. If this problem was mine, I'd be looking to review and correct the Saddlematic's movable pin's adjustment, and be sure of where I'm aligning it to. I followed the written instructions, no outside advice, and all was well. Good luck with this. Chasing nuisances like this can sure take the fun out. I'd sure like to hear how this turns out.
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#7
09-17-2023, 07:04 PM
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A tape measure is not good enough for this very precise measurement. I have a bridge saddle jig I made about 25 years ago that still works. It routs out a standard angled saddle slot, probably based on Martin but I don't remember now, then measure down the center of the fretboard from nut to 12th fret dead center using a precision steel ruler. Then measure from the 12th fret dead center to the center, left/right of the saddle and also the center of the width of the slot and add 0.1in.
This allows for a bit of wiggle room on a 1/8th in saddle but almost every time it's 'good enough.' It's also important to have the nut set up right for intonation too.
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#8
09-18-2023, 02:55 AM
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Quote:
Somehow, you have ended up with your bridge too far away from the nut. Or you have ended up with your nut too close to the bridge! And I would check that first, just to exclude it as a possibility. Measure the distance from your nut to the first fret and check that matches your fret position calculator. And, as Rick-Slo said, capo and the second fret, check your guitar tuning, and then see if the fretboard still plays flat. Doing these two things will isolate the saddle position as the problem. If it is still the saddle position as the issue, then you know that you have placed it too far away from the 12th fret. You have over-compensated the guitar. Then you can dig into the weeds to work out how you made that mistake. Additionally, put on a new set of strings. If the strings you are using for your intonation tests have been on and off the guitar a few times then they may not be vibrating correctly and so can give false readings when setting intonation.
__________________
I'm learning to flatpick and fingerpick guitar to accompany songs. I've played and studied traditional noter/drone mountain dulcimer for many years. And I used to play dobro in a bluegrass band.
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#9
09-18-2023, 03:25 AM
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I suspect your tape measure is the problem.
Tape measures have a little doodah at the start (a shiny metal triangle) which isn't fixed fully. The idea is that you hook this over the end of what you are measuring, and then pull the tape taut, at which point the measurements are (fairly) correct. If you push the movable doodah against the face of the nut, you're reducing the tape measure length by 1/8 inch or more. A steel ruler is far better for this kind of measuring.
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#11
09-18-2023, 07:10 AM
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I've built several guitars, intonation has not been my problem (i have other problems!) so far. If you read the stewmac fret spacing calculator you will note that the bridge position is the scale length PLUS some amount usually a little more than 1/16" and less than 1/8". What I really want to comment on is the "doo-dad" at the end of a tape measure. The fact that it moves is intentional and necessary. The key is to make sure that it is functioning properly. The doodad is intended to move by a distance that matches its own thickness. The purpose is to be able to measure something "outside" - with the doodad hooked over the edge of the part in question, or "inside" - butted up to an attatched piece that does not allow the outside measurement. An example might be the length of a tenon. Checking a tenon would not typically be something that you would check with a tape measure. It's just an example of the tecnique. There are methods to calibrate a tape measure, that will allow it to function accurately in the appropriate conditions. Having said that, there's nothing that would prevent a person from using a tape measure to position a bridge. But..a steel rule will not flex and a tape measure might. A piece of thread is handy too, to make sure you're centered and aligned with the pin holes in way that works. This really is a case of measure many times, check and re-check. At the end of that, it's equally important to have a system that will prevent the bridge from moving when glued and clamped. No intent to be controversial with this but, I've taught dozens of people about the tape doodad, as it comes up often in a woodshop. The same way an old guy taught me many years ago.
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#12
09-18-2023, 07:21 AM
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Quote:
The "free play" designed and built into the modern factory produced tape measure is there to compensate for the thickness of the metal the hook is made from when making inside or outside measurements. This amount is normally around 1/32". The only time you'll see a difference between inside and outside measurements exceeding anything more than .010" is when there's been damage to the hook mounting rivets OR (much more likely...) if the hook is bent from being accidentally dropped. It's easy enough to test your tape measure by making an inside and outside measurement and truing up any bend in the hook end to correct for hook damage. I've actually observed a tape measure owner "tightening up" their errant tape measure by whacking the rivets with a hammer!  A quality tape measure is usually printed accurately and I use mine often for all types of work requiring fairly precision measurement. The trick is to NEVER use the hook, holding the tape at the starting point of your measurement at the center of the printed 1" mark. You do, of course, need to remember to subtract that extra inch when you are reading or marking out your measurement. No rant intended, I just hate to see a good tool get a bad name by no fault of its own.
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#13
09-18-2023, 08:25 AM
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Quote:
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#14
09-18-2023, 08:27 AM
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Assuming nothing mechanically wrong or out of place, have you tried a string change?
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#15
09-18-2023, 08:56 AM
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Quote:
__________________
Derek Coombs Youtube -> Website -> Music -> Tabs Guitars by Mark Blanchard, Albert&Mueller, Paul Woolson, Collings, Composite Acoustics, and Derek Coombs "Reality is that which when you stop believing in it, doesn't go away." Woods hands pick by eye and ear
Made to one with pride and love To be that we hold so dear A voice from heavens above
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