Geometry on a brand new OM28

[ChrisN]

Originally Posted by redir

It's an age old builders trick. I guess coming from the perspective of building a guitar, i.e. it's never had strings on it yet. In determining the proper neck angle you lay a straight edge across the fretted fretboard to the exact location of the saddle and measure that distance and set it so that the height is about 1/32nd inch over your target bridge height and to achieve the goal of getting about 1/2in string height over the soundboard at the bridge.

So I use that same method when repairing guitars as well. Just try it anyway and it will be an interesting experiment. Take the string tension all the way off and do the straight edge test. If it's now flush with the bridge or even a hair higher then imho you have a perfect thing going on, a responsive top. Most guitars are overbuilt so you hardly see any change under string tension.

That makes sense. I have tried that experiment with a newish Taylor vs. a '70s Japanese lightly built all-lam that needs a reset and has a little belly, both with flat fretboards (to compare). Taylor GC (short scale light strings) moved a hair more than 1/64, while the all-lam (long scale light strings) moved a full 1/32. I concluded the all-lam was more lightly built, or its neck was weaker from being strung for 45 years, couldn't be sure which one. Or, it could also have been the longer scale applied more force to the all-lam. These observations are why I ask so many questions - too much to know meets lots of variables!

[charles Tauber]

Originally Posted by redir

Just try it anyway and it will be an interesting experiment. Take the string tension all the way off and do the straight edge test. If it's now flush with the bridge or even a hair higher then imho you have a perfect thing going on, a responsive top. Most guitars are overbuilt so you hardly see any change under string tension.

As part of that experiment, measure the vertical distance from the guitar top to the bottom of the straight edge, adjacent to the bridge, while at full string tension. Repeat with no string tension. Observe the difference in vertical measurement.

Many luthiers include in their never-before-strung layout some allowance for how much the top will rise when subject to string tension. About 1/16" is a commonly used value, in my experience.

[charles Tauber]

Originally Posted by ChrisN

Left out, however, is another concern, one that I would have (and the OP may have) on a new guitar, and that is, how much useful life is left in the guitar without major surgery (including bridge height reduction)?

I had thought that I had adequately addressed that, but, obviously, not:

Next, we want to have sufficient saddle height projecting from the bridge that, should it be required in the future, for a variety of possible reasons, there is enough there to accommodate that change in saddle height AND still have a sufficient break angle of the strings over the saddle. Many luthiers/manufacturers want to see a minimum of 1/8" to 3/16" at the bass E, a little less, perhaps, at the high E.

That assumes that the action is where the player wants it to be AND still has 1/8" to 3/16" of saddle height at the bass side.

The short answer is that it doesn't appear that the OP's guitar has that, or it is marginal. The shorter answer is that in all probability, he'll need a neck reset, or bridge shave - if the bridge has sufficient thickness to allow it - sooner than later. It is difficult to predict which guitars will need a neck reset and when they will need it.

The measurement goals you mention can all be achieved on a guitar that is well down the road to its first reset, which is fine if playability is the only goal.

Playability should never be the only goal. Longevity should be built into the instrument, including its neck angle. That is a very good argument for more modern neck joints that allow the neck angle to be reset fairly easily.

I'd love to learn I'm concerned about nothing!

Longevity should be a concern of every maker/manufacturer and most players. It seems to be a relatively recent phenomena that many one or two year old guitars are in need of neck resets or that players/buyers need be concerned about it.

[Howard Klepper]

From the numbers given, if they are accurate:

Neck angle is perfect. You have a tall bridge, and that seems to have been unnecessary. You are measuring 13/32" bridge (wood only) height at the low E, so about 7/16" at the center (which is where bridge height should be measured). Saddle height over the bridge is great. Relief is great.

If you were to bring the action down to what many people consider standard--6/64 and 4/64 (I personally like to set a guitar up to 5/64 and 4/64) you would be taking 1/32 off the saddle at the high E, leaving 1/16" of saddle exposed. That is about as little saddle exposure as you ought to have. But you have about 1/16-3/32" more bridge than is needed. Martin uses 3 different bridge heights to compensate for variation in neck set angle. Your guitar got their tallest one, when it should have gotten the middle one.

The fix is an easy one for any competent tech (these are in shorter supply than they ought to be, so be careful if you get the work done): take the bridge down by about 1/16" and the saddle by about 1/32" (maybe a bit less on the bass side, depending on how you play).

You shouldn't have to do this on a new guitar. You may choose to return it and swap for one with a more ideal setup. But if this guitar speaks to you, it can be made right with bridge and saddle shaving, which are not a big deal. If you have the work done, have it done only by an authorized Martin repair shop (need not be a dealer) to avoid any warranty issues in the future.

I didn't take the time to read all other replies, in case someone already covered all this.

[canyongargon]

Lots of really great input here guys. Thanks so much, lots of considerations I never would have even thought of. I guess the heart of my question is "Is there any reason given my measurements that it would be inadvisable to hang onto this guitar?"

I really like everything about this one except that the setup is a hair high from the factory. The straight-edge test tipped me off that I should ask better minds for some advice. If it can be brought down to where I'd like without trouble and nothing about my measurements screams that there's something drastically wrong, then I'm just wondering if anything about the guitar screams "foolish" if I were to hold onto it.

[ChrisN]

Originally Posted by canyongargon

Lots of really great input here guys. Thanks so much, lots of considerations I never would have even thought of. I guess the heart of my question is "Is there any reason given my measurements that it would be inadvisable to hang onto this guitar?"

I really like everything about this one except that the setup is a hair high from the factory. The straight-edge test tipped me off that I should ask better minds for some advice. If it can be brought down to where I'd like without trouble and nothing about my measurements screams that there's something drastically wrong, then I'm just wondering if anything about the guitar screams "foolish" if I were to hold onto it.

Given the excellent input above (not mine), it appears you have nothing to worry about so long as you're willing to spend a bit more $$ to shave the bridge/saddle to get the action where you want it while keeping sufficient saddle exposure and string break angle. You should not have to do that, and I assume your dealer would allow a swap, but that solution may be preferable for you to swapping for a different guitar that might not sound as good as the one you have.

Per Howard's excellent input, your guitar's issue isn't that the neck on yours wasn't set to the correct angle, it's that the assembler grabbed the wrong bridge for that neck angle - if the next-lowest-thickness bridge had been used, instead, then your guitar would easily pass the straightedge test. I don't know if bridge-grabbing is a by-the-book measurement, or a judgment call for the operator. If you had your measurements, but with a shorter (LOWER!, scream many) bridge already installed, then that might be a different issue.

I mentioned Godin and noted they, too, use different-height bridges. I've got an A & L Ami that's in your Martin's position - straightedge hits 1/64 below the bridge top and the low E is just a smidge under 1/2" off the top. The bridge height appears thick at 12/32 - to get my preferred 5/64 low E action, the saddle midpoint is only 3/32 exposed at the middle, which is insufficient by most standards. By comparison, the Taylor next to it easily passes the straightedge test, and its bridge height is 3/32 lower, at 9/32. The Taylor's low E sits only 13/32 off the deck with low E action of 5/64 requiring a 5/64 saddle exposure (sufficient). Arguably, the Taylor should have had a slightly taller bridge affixed.

[mirwa]

Originally Posted by canyongargon

I really like everything about this one except that the setup is a hair high from the factory. The straight-edge test tipped me off that I should ask better minds for some advice. If it can be brought down to where I'd like without trouble and nothing about my measurements screams that there's something drastically wrong, then I'm just wondering if anything about the guitar screams "foolish" if I were to hold onto it.

You will note my earlier response, still stand by it, if it plays great leave it alone do not look for issues. No guitar is perfect.

Guitars from the factory are IMO a tad high to start with, but..... they have to be shipped around the world, stored in the most unforgiving enviroments and then be displayed and ready for sale straight out of the box. So manufacturers have a tendency to set a smidgen high.

For disclosure, I am a Warranty repair agent for Martins Distributors in my locality, occasionally we get one or two guitars come in with a high action necessitating a neck reset, this is a rarity but it does happen with most manufacturers.

Straight edge under tension shooting just shy of the top of the bridge is fine.

Have a competent person near you tweak the action to suit you. It is the best money you can spend, its crazy when people buy 2000-10000 dollar guitars and wont go that extra 60-100 dollars to have it professionally setup for them.

Even if you can set the guitar up yourself, get someone that does it for a living to do the first one, then you know what your guitar is truly capable off and it sets a base line for you to adjust to from then on.

Steve

[canyongargon]

Originally Posted by mirwa

You will note my earlier response, still stand by it, if it plays great leave it alone do not look for issues. No guitar is perfect.

Guitars from the factory are IMO a tad high to start with, but..... they have to be shipped around the world, stored in the most unforgiving enviroments and then be displayed and ready for sale straight out of the box. So manufacturers have a tendency to set a smidgen high.

For disclosure, I am a Warranty repair agent for Martins Distributors in my locality, occasionally we get one or two guitars come in with a high action necessitating a neck reset, this is a rarity but it does happen with most manufacturers.

Straight edge under tension shooting just shy of the top of the bridge is fine.

Have a competent person near you tweak the action to suit you. It is the best money you can spend, its crazy when people buy 2000-10000 dollar guitars and wont go that extra 60-100 dollars to have it professionally setup for them.

Even if you can set the guitar up yourself, get someone that does it for a living to do the first one, then you know what your guitar is truly capable off and it sets a base line for you to adjust to from then on.

Steve

This is what I'm thinking as well. Off for a setup she goes.

Thanks to everyone for their insight.