Official Luthiers Forum!

I have been following a couple of threads recently-

“Truing Upper Bout” and “Fretboard Angle Question”

I’ve been very interested since I’m at this stage myself.
I‘ve posted some pics that show a test set up as Hesh suggested.

It seems I have the opposite scenario that Larry had.

Hesh, I hope you chime in here, cause in the StewMac instructions on page # 23, it says-

“...Wood to remove from the heel to change the neck
angle so that a straightedge laid on the frets will be
flush with the top of the bridge”

Where you had said-

“A much simpler method is to bolt on the neck, place the fretboard on the neck,
place the bridge where it will go, and place a straight edge on
the un-fretted fret board pressing it down to kill any bow.
You want the straight edge to be just over the bridge 1/16" or so.
If it is below the bridge height or more then 1/8" above the bridge adjustment is needed”

Please understand that I am not questioning your expertise.
Its just that I’m a little more confused than I was before.

The following pics are for the most part self explanatory.
But, do show in a bit more detail of my situation.

I’m pretty sure of some of what I need to do, but, not all.

So if anyone feels up to it, let me know what you think.

The first pic is just an overall view.











Checking the Bridge Set up





12th Fret Check











The gap at the bridge is almost exactly 5/32"







Gap under fretboard is approx. .065" There is also a gap under the fretboard where
neck meets body of approx. .030"





I should note that the crown height of the fret wire I’m using is .050"

Thanks for looking!

Robert

_________________
Everything has beauty, But, not everyone see's it!

It looks to me as though you might have just a bit too much neck angle. The end of your fretboard should touching the top.
I would recheck that and see what you come up with. I had a similar situation like that recently myself.
Don`t take my word for it though. The experts will be along shortly.
Coe

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Give me 50 cents worth of regular.
Check my oil too, if you don`t mind,,,

Good pics, Robert...they really show the issue. Looks like you need to remove stock from the top of the heel. Are you familiar with the sandpaper flossing method? The angle will shallow out and the FB extension will lay flat. Keep checking the projection occasionally to see how it's changing.

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JJ
Napa, CA
http://www.DonohueGuitars.com

The way I had it explained to me was like this (gee, I hope I'm remembering this correctly): The straight edge, laid down the bare neck (no fretboard) should be approximately 1/16 - 3/32 off the top where the front edge of the bridge would lay.   

Everything else is just a math formula from there...depending on the thickness of your fretboard, height of the frets, desire for the saddle height, etc.

BUT, like was said earlier, smart people will be along any second to completely disagree with what I just said.   

_________________
Eagles may soar, but weasels don't get sucked into jet engines.

Hesh is right Robert, relax and listen to good music while flossing those cheeks, it's a common thing that happens to all of us, your progress is phenomenal my friend, keep up the good work!

Serge

Hi Robert,
My setup differs slightly from the way Hesh does his. I like to be able to
lay a straightedge on top of the frets and have it fall right on top of the
front edge of my bridge (which is just shy of 3/8" tall). If anything, it is
better that the neck angle be slightly higher than the height of the bridge
that have it be lower.

--
Simon

Thanks All,

I really appreciate your quick responses on this issue!

Your suggestions of adjustment to the cheeks of the neck are sound,
and it’s exactly what I intend to do.
I must admit, I didn’t know that it was generally acceptable for a fretboard to slightly fall out of plane.
I do have the desire to prevent this though, and I’ve got some ideas on how to do it.

Hesh, thank you so much for another very detailed explanation!
I know it takes some time to type all that out!

However, I have to ask another question in regards to, what seems to me to be two different
approaches, with two different results. StewMac’s and Yours.

That is; with StewMac’s version, the straight edge is expected to ride flush on the bridge,
(There is no mention of saddle) while it is setting on a FRETTED fretboard.

Where as, with your version; the straight edge laid on an UN-FRETTED fretboard is expected to be
1/16" above the bridge.

I do know, that many things come into play as adjustments go, saddle height, nut height,
fret wire crown height, and others.
But, in general, given the two different approaches.
Would I be correct to assume that StewMac’s version lends itself to a low action?
Where as to your version Hesh, would lend itself to a higher action?

Or perhaps, I’m just splitting hairs here. Don’t know!

Robert

_________________
Everything has beauty, But, not everyone see's it!

This is a little off the subject, but it looks like you are using the 25.4 scale. Just make sure you add ~.15" compensation before you are ready to glue the bridge down.

_________________
Matt Jacobs

"Don't tase me bro"

That's a GREAT pictorial Robert. Like most have said your solution lies in the suggested neck angle change. I just wanted to post a thank you for taking such great pictures and showing the problem so clearly.

What I prefer about your situation is that your upper bout angle looks like its perfect and all you have do is change the neck angle. I had a situation where the upper bout angle was wrong and it took a bit more effort to get that right. Let us know how the solution works.

Larry

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Thank You and Best To All

One way to make the neck set easier from here is to chisel away material from the interior of the heel (the part of the neck heel that contacts the sides) leaving about 1/8 of an inch around the edge. This way you are only dealing with the edge of the heel to get the set right, instead of the whole heel which is a lot of wood.
This is the way I do it.

Good luck and take it slow, this is not a huge problem.

Blake

you have not mentioned why the fretboard is above the body at the neck/body join. to me this indicates that the neck is not seating in the mortice correctly.

i did not see any mention of the style of neck joint being used, i.e., whether it is a straight or a dovetail mortice and tenon.

regardless, before you decide to do anything to the heel, you have to get the neck sitting so that the plane of the neck surface, and therefore also the underside of the fb is flush with the body at the join.

you have not mentioned how thick your bridge is, but in the photo it seems very thin.

i have always been in the camp of having the plane of the top of the frets hit the top of a 3/8" thick bridge both when building, and with whatever bridge is present when resetting necks.

what angle did you cut the cheeks of your neck heel?

And so the confusion begins .

Michael, how much saddle height do you end up with ,,with your , top of the frets flush with the bridge top method . ?

_________________
CRAIG LAWRENCE of AUSTRALIA
_____________________________________________

      This is a typical situation for newbies. If I can I would like to make a few points about the setup issues.
    In a perfect world your set up should place the strings about 1/2 inch off the top , your saddle you would like to see at about .100 out of the bridge with a break angle over the saddle of about 45 degrees.
      In martin kits the bridge is .410 at the highest point . If you get real close you can allways take a bit off the bridge.
        Most people have the idea that a flat top is flat but it isn't . I use about a 28 foot radius and with that in mind you would see the neck a bit lower in the block that the photo in the above post . That would also set the action line about where is should be.
     When I preset my necks I like to see 1/16 off the top at the point of the saddle so all of you are dead on in that spec. All have given good advice and should have a good result.
      I just feel that if the side is profiled befor the top is placed this helps to eliminate the dreaded 14th fret hump. For those without a radius dish you can get a similar result using sanding blocks and taking a 1 degree lean to the neck block from the point of the top of the soundhole to the neck block.
     All in all this is a great illustration of what can happen and why. After you learn all the little things your building will improve. After all we are hear to help each other. We can't make all the mistakes outselves .
    Again nice photos and they show the situation very well.
John Hall
http://www.bluescreekguitars.com

Thanks to All for participating in this thread!

This issue seems to be one of those where the more I talk about it, and the more I read the posts,
the more questions I have.

But, before I do that, I got to thinking, I should understand a little more about action.
Understanding action may just clear up a lot of what I’m thinking about, and lead me to methods
of adjustment that will produce the desired results.

So, When I said-

“Would I be correct to assume that StewMac’s version lends itself to a low action?
Where as to your version Hesh, would lend itself to a higher action?”

Then you said,

[QUOTE=Hesh1956]
I did a few Stew-Mac's way and ended with very short saddles and higher action. [/QUOTE]

Do I have this action thing backwards?

When strings are closer to the frets, is that HIGH action?
And, vice versa for LOW action?

And, while we are on the subject.

What action is considered to be (In general) widely accepted.

The following is from the StewMac Manual for string set up & action,
and perhaps this is the general “rule of thumb”

"Position the high and low E-strings on top of the nut at the
desired distance from the edge of the fretboard. 1/16" from
the top edge of the fret end bevel is an average distance.
Pencil these positions on the nut, and file shallow
slots for each string. Leave at least 1/32" clearance between
the bottom of the strings and the top of the first fret.
Install a guitar capo behind the first fret and tighten it just
enough to pull the strings down for clearance between
the bottom of the strings and the top of the first fret. Set
this clearance at about .020" below the treble E-string, and
.030" below the bass E-string. Use .020" and .030" guitar
strings to measure the clearance as the capo is tightened.
Now measure the overall string action at the
12th fret. A comfortable medium action is about 3/32" to
7/64" under the bass E-string, and 1/16" to 5/64" under the
treble E-string."

I do get the feeling though, that action may be a personal preference.
So, I may have opened up the proverbial “Can of Worms” on this one!

Looking forward to the chiming!

Robert

_________________
Everything has beauty, But, not everyone see's it!

strings HIGH off the frets is a HIGH action.

I had this same problem with my evening class Jumbo.

Sam Irwin (of Lowden & Avalon) was the course tutor.

He laid the fingerboard flat on the top and drew a pencil line on the heel parallel with the top obut/neck join onto the heel.

then he flipped it into a vice and ran the sharpest chisel I have EVER SEEN down it and sorted the problem in literally 3 minutes.

30 years experience makes a difference apparently!!

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yup, take 1/3 what you think you need to.

check

take off another 1/4mm

check again

etc.......

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My soundclick xx luthier blog xx luthier soundclick

depending on the action desired by the client, i aim to have about 3/16" - 1/4" of saddle. this allows for the saddle to be lowered whilst still maintaining an adequate break angle as the top rises with age.

Action is the set up for the neck and this is what makes the guitar playable. Looking at the phsyics of this you need to look at energy transfer to the top through the bridge and saddle. The best mathmatical formula places the the geometry at what I stated.
   This sets things up so the rotaional forces of the saddle and the tension of the strings will be balanced. This way your energy transfer is as efficient as you can get. If you go higher the roation forces start to overdrive . much lower the tension.
   I agree there is a slight tolerance here of maybe 3/32 but this is the target area you need to consider. Mass is the other. Older martins had some pretty high bridges compared to the modern ones of .410
   It isn't allways as simple as it seems. Math and plotting the vector or resultant forces allows you to manipulate the forces at hand to get the most efficient energy transferance.
   Mass of the bridge and structural intergrity also need to be considered. I like to see .125 at max but have gone a bit higher on saddle height out of the bridge . Too high and the forces can cause the bridge to split. The break angle is important but remember that the total height off the top is how you can plot your rotaional forces. Too high and you will cause the top to cave in at the front ot the bridge . This also places undo stress on the bracing.
john hall
blues creek guitars

i is interesting, hesh, that you look at 1/8" as a mx sadl]dle height whereas i consider it a minimum. any less than that and the break angle is too low for my taste.

and the .410 bridge is thicker than i would aim for, i.e., 3/8" or .375.

on older martins you will see a range of bridge heights as a result of maritn's assembly process. they would fit the neck, then select from a range of bridge thicknesses to suit the neckset.