Setting intonation on Gibson/Loar

[Hambonepicker]

Has anyone had to move any frets on their vintage Gibson or Loar mandolins?

Wanting some elaboration on something a performer said in Vintage Guitar magazine...

this is what they said :

Loar-period mandolins have a very flat second fret and most of the people that make copies of those mandolins have used the scale off of ’em. A lot of the earlier copiers, copied that same bad scale. I’ve had the frets moved on a couple of mandolins.

and this is the link where they said it :

http://www.vintageguitar.com/artists/details.asp?ID=140

Wondering how often this is a problem on old mandolins; personally, I haven't seen as many of them as a professional luthier or performer would have seen.

Hambonepicker

[Steven Stone]

I did that interview with Norman Blake back in 2001.

Personally I've never seen or played a poorly intonated Loar, but most I've played have not had original frets and some, like Grisman's "Crusher" have had their fretboards replaced.

Norman is a stickler for tone, so if he says an instrument is improperly intonated chances are he's correct.

[danb]

There was a "Bad batch" of fingerboards in 1924. I had an Ajr with frets that weren't even parallell. I'm not aware of that turning up on any F5s though..

[Michael Lewis]

This was covered in a previous discussion a few years ago. If I recall correctly Charlie even commented about it.

[Hambonepicker]

I just joined this board a few days ago. Are all the old threads still available?

I could be intimidated by some of the names here, or by the collective knowledge you all display here - but instead will try and learn from your postings. This vintage and historical stuff is quite new to me.

I ought to be reading more current publications, I suppose.

Thanks for the illumination.
Regards,
hambonepicker

[danb]

hambone- I don't recollect that topic coming up before but I bet it did. There is a search feature top-right on the page here that can help you find old topics. Generally very little gets deleted here, I think we go back several years..

[evanreilly]

I remember one night after a "Down From the Mountain" show I was listening to Ricky Skaggs give an opinion of Nancy Blake's Loar (an April 25th, '23). He was telling that it was a real dog and needed a lot of work, and apparently neither of them wanted to fix it up.
So maybe Norman's perspective was formed around the condition of Nancy's mandolin.

[Darryl Wolfe]

Most all Gibsons of that period have a flat 2nd and or 3rd fret. #All it takes is a little "acquired" tuning to compensate for it. #I believe I remember CharlieD's explanation being that they did not have infinite adjustment in their cutters and used 1/64 or 1/32 shims between them, hence some minor difference bewtween theoretical spacing and what they #could do (in the mass production world)

ps: I believe this is dicussed somewhere in the original LOPD thread

also, Ricky Skaggs first brought this up to me in the late 70's. He demonstrated it on his Loar and then checked mine to see if it did the same. It did.

[Jim Garber]

I believe that there was a period (23-24) where they produced scales that were more than just a little off. I was at Bob Jones shop and he lined up the fretboard of my 24 Gibson against a std one and the upper frets (as I recall) were way off. He recommended puttin on a replacement one in order to make it right.

I don't know about the Loars of that period but I know there can be problems with A2Zs.

Jim

[Tom Smart]

Most all Gibsons of that period have a flat 2nd and or 3rd fret. All it takes is a little "acquired" tuning to compensate for it.

Could you explain this "acquired" tuning?

[danb]

sometimes changing the angle of the bridge slightly, sometimes it's setting down the electronic tuner and makeing a few compromises

[Darryl Wolfe]

Ha. I saw that coming. Actually I cannot, it depends on the person and the mando. But what I am referring to (for example only) is tuning say the 2nd string very slightly sharp to compensate for the problem at say the 3rd fret or for a particular chord. Depending on your style ect you end up with a tuning that works best for you. You may hand the mando to someone else and they will start tuning it and get it all messed up.

This is very similar to Martin guitars with B stringitis. There is a slightly flat or sharp position for the G string that makes it chord better

[Darryl Wolfe]

sometimes changing the angle of the bridge slightly, sometimes it's setting down the electronic tuner and makeing a few compromises

Exactly. Forget science and "acquire" a tuning that works best for the mando

[Tom Smart]

OK, thanks. Maybe that's why I'm constantly fiddling with the A strings on my snakehead.

[Chris Baird]

From what I remember Charlie saying; The old standard was to round the fret position to the nearest 1/64". That gives a tolerance of about .0075". The modern approach is to round to the nearest .001" which gives a tolerance of .0005". As I calculate it, the 3rd fret position seems to land such that rounding it to the nearest 64th causes nearly the greastest possible error; depending on how you calculate it is .005-.007" too close to the nut. But, even .007" isn't much and if the fret intonation is off enough to hear it is likely a combination of calculation inaccuracy coupled with inaccuracies due to the jig or operator. However, the further you go up the neck the more small inaccuracies become noticeable.

[uncle ken]

I got out my calipers and measured the first three frets on a '20 f4, '24 snakehead and '29 f5. The '20 and '24 were identical and quite a bit flatter .020" to .030" than the 29. When tuning, I also seem to get much better results when tuning the snakehead using an old 35 year old strobe tuner than when using a modern tuner. It's a different technology and for some reason it ends up sounding noticeably better.

[Jim Garber]

Perhaps on I wrong on this count, however, from what I have heard, these inaccuracies were a mistake in spacing the frets, not a different way of measuring. Maybe they inaccuracies referred to above are the subtle ones that occur in all mandolins of that period, but i think the one that was on my 24 was very obviously a miscalculation by a considerable amount on the upper frets.

I would assume that it might have been a mis-measuring of the pattern used to cut some of those fretboards.

Jim

[Darryl Wolfe]

You are right Chris. Charlie used the term "rounding" to the nearest 64th. I assumed arbor mounted cutters with shims from the comment. It has not been proven out as to how they actually cut fret slots

[danb]

I took an ajr with horrible frets to frank ford, and he told me at the time he suspected a "bad batch" of fingerboards. Frank, if you're reading this- did you keep any notes on where you've seen this issue? mine was a late '24 snakehead ajr. Gorgeous tone, needed a new fretboard fitted to sort that issue out though.

Tom- I'd suggest a certain family member of yours as a great choice to sort that fingerboard out for you

[Rick Turner]

When I worked for Gibson, there was a tale of a guitar fret slot arbor that had been reassembled after the saw blades were sharpened and a couple of the spacers got put on in reverse order. This would have been sometime in the 1970s or '80s. S... happens, as it is said, only when it happens in a factory, a lot of stuff can go out the door before anybody figures it out. So if there is this 'bad batch' of mando fingerboards out there from the Loar era, it's entirely possible that it was a case of a couple of arbor spacers reverse ordered...

As for the tolerances on arbor spacers...they were perfectly capable of working to within a thousdanth or two in those days, and it's well known that with that kind of setup, you have to be extra careful when making the spacers because any consistent errors add up. It's better to be off plus and minus than consistenly plus or minus with a couple of octaves worth of blades and spacers all packed together.

[Bill Halsey]

Agree with Rick. The arbor I saw for mando boards had solid spacers, and when you add up the cumulative tolerances for 28 spacers (plus the nut to the first) and 29 blade thicknesses, it can go some awry. There were no engineering drawings for these fingerboards, so there was plenty of room for "creativity."

The best boards I've made were done with a 24" vernier caliper hooked over the nut end and, undercutting ever so little, scribing the centers of the fret positions with a very sharp knife point. I have also done very well with a Starrett steel rule graduated in 1/100" clamped to the board, and eyeballing it. Works fine, long as you read it right.

[mrmando]

I recall some sort of tale about a badly intonated Loar, involving Danny Ferrington and Peter Ostroushko, along with two or three chorus girls, a case of vodka and half the city council of Oshkosh, Wisconsin...

[Tom Smart]

Tom- I'd suggest a certain family member of yours as a great choice to sort that fingerboard out for you

Actually, I think you guys who study all the minutiae of old Gibsons probably know more about their quirks than Lawrence would...

...unless you mean getting him to build me a new fretboard. But I don't think it needs one. Lawrence used to own a '23 or '24 A-Jr, and has played my '23 A-1. He pronounced them both great instruments, and never mentioned fretboard intonation, even though he has a far better ear than I do.

I've long suspected the second and third frets of being very slightly flat, and when I hold that fingerboard up against my Smart F5, I think I can see some tiny differences especially at those frets. But I don't hear it as intonating "wrong" so much as "different," in a way that is part of the instrument's character. For example, a two-finger C chord, which is normally a bright-sounding chord, seems just a little darker on the A-1.

It's kind of like the difference between "wet" and "dry" tuning on an accordion. "Wet" is by definition more "out of tune" than "dry," but it's a better sound for certain types of music.

Make sense? Or am I all "wet"?

[Paul Hostetter]

I have seen a great many Gibsons that have had inaccurate boards, and none were isolated to any small period. I happily play one, my marvelous 1917 A-4, for which I have evidently acquired the ability to tune and play without wincing, even though I know very well the frets are wrong. But I have replaced boards for people who couldn't adapt, who couldn't take the weird notes inherent in the old boards.

Obviously most people do accept them, or at least spend a lot of time trying to tune and in various mental states leave it at that. In fact, I always expect Kalamazoo Gibson boards to have a spacing anomaly of some sort, so much so that I don't even bother to look unless a customer mentions it. And I think Martin had a similar slotting machine, and similar issues. I have a fleet of Martin guitar boards which, when lain side by side, reveal the extent of the human mind's ability to forgive. Gibson was not alone.

It's not difficult to lay out a template based on the adjusted 12th root of two that identifies the ideal locations for Gibson mandolin (or any other instrument's) frets. Once you have it, and you start really looking, the discrepancies among actual instruments are astonishing. Yet generations of players have just learned to deal with it. They never suspected their frets weren't and never had been in the right place.

I saw the Gibson fret saw on Parsons Street when it was apart once for sharpening. This would have been in the 60s, but it was a very old machine. As Rick indicated, it was like a big table saw through which the boards were pushed at right angles to the blades, cutting all fret slots at once. A whole bunch of circular blades separated by lots of thin brass shims were arranged on a long arbor, like beads. The blades were farther apart at one end, and really close at the other, and depending on which boards for which instruments they were cutting, the blanks were run through at the appropriate place, left or right.

The brass shims were paper-thin (much thinner than a 64th) and were arranged in order to make the precise separation between the blades that yielded supposedly correct spacing. All the blades and shims had to come off so the blades could be sharpened. If the shims weren't returned just right, or checked well enough for accuracy during the "stringing" process, the blades came out in the wrong place. Trouble.

I have no idea how often they pulled the thing apart for sharpening, but you can imagine it happened often enough, and human error was common enough, that the blade spacing could have been, um, variable in a variety of ways. I also don't know what their acceptable margin of error was, but it had to be large, because some of those boards were really impossibly "off." And it's not due to wood shrinkage.

The ability of the brain to hear in tune when the strobe tuner is fervently not agreeing is a huge topic for another day. Just be thankful the mind's appetite for sweetness covers and smoothes over a multitude of difficulties, because they are out there in spades.

[Paul Hostetter]

Tom - wet tuning in an accordion is the process of taking (usually) three reeds, tuning one right on pitch, and the other two on the key or button to certain deliberate intervals above and below. IOW, taking a trio of A reeds and tuning them all to 440 yields a completely dry sound. Tuning them 435 - 440 - 445 yields a wet one, and the net effect is a very definite A, but with character.

This is very different than being out of tune or having bad fret spacing.

BTW, say howdy to your brother for me, I've been thinking about him lately because of an invasion here of Idaho-types.