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Truss rod, Top question (pics)
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Author:  robertD [ Sun Nov 25, 2007 1:21 am ]
Post subject: 
Hello All,

Ran across a situation yesterday.

First, some information.

This is a Martin neck (2nd), a Martin fret board, and a Martin truss rod. The spruce top measures
right at 0.100".

By the pics, you can see that the top does not fit between the truss rod and the bottom of the fretboard.
I’m assuming that a simple notch out of the Top will remedy that problem, and I know I need to
drill a hole in the brace next to the sound hole. However, I’m really concerned to what I should
do about the first brace in the upper bout. It looks to me, that the truss rod adjusting nut will be very
tight to the bottom of the Top.

Is this a typical situation? If so, will I need to chamfer in a trough in the foremost upper brace?

Also, what do I do with the black strip that came with the truss rod?

Thanks in advance!

Robert






Author:  grumpy [ Sun Nov 25, 2007 2:28 am ]
Post subject: 
What he said. The rod doesn't go under the top, but through it. Cut the area where the rod goes.

Can you not scoot it further forward, also?  Looks to be a lot of it sticking out...
Author:  robertD [ Sun Nov 25, 2007 6:01 am ]
Post subject: 
Thanks guys for responding so quickly!

Todd,

After reading your post, I decided to make some measurements, and take a closer look at things.
You’re right about the fiber cap plus the offset giving room for the nut. Though, it still looks like
the nut will be right up against the top. I suppose that’s OK, but, I will still need to deal with the
flat (transverse?) brace.

I like your suggestion to make the channel deeper, however the depth of the channel is 7/16" and
the depth of the neck, at the point where the curvature of the heal begins, is 11/16". That only
leaves about a 1/4" of neck under the truss rod. Perhaps that’s OK.

Grumpy, Or should I say Mario!

From what I can tell, the rod is in as far as it can go.

The following are some measurements, and a few more pics, to help explain.

The neck is for a 14 fret guitar.
Total truss rod length = 15-15/16"
The truss rod extends from the heal joint 2-15/32"
The neck block measured from the body inward is 1-3/4"

Right now, its looking like, all I need to do, is thin down that flat brace to about 1/16" thick, and drill a hole in the taller brace.

What do you guys think?











Author:  grumpy [ Sun Nov 25, 2007 7:02 am ]
Post subject: 
Cut away the top and slice through that popcycle brace....

then do as Todd says. Drill, and scoot it up to the nut by chiseling. I drill a 1/4" access hole after the body is closed, using a long spade bit. Nothin' to it....
Author:  robertD [ Sun Nov 25, 2007 7:25 am ]
Post subject: 
Ok! Just so I know what I’m doing here.

The popsicle brace is the flat one?

Drill the hole through the upper transverse brace.

Chisel out enough wood in the channel of the neck to allow the end of the truss rod to line up
with the fretboard side of the nut. (not under the nut, right?)

After the body is closed, trim away top, to allow room for truss rod extrusion.

Unless I’ve missed something, I think I got it!

Thanks so much Guys!

Robert
Author:  grumpy [ Sun Nov 25, 2007 8:24 am ]
Post subject: 
Sounds good. I actually run mine right under the nut, and have, on occasion, even ground down the end of the rod to the headstock angle. I feel these rods work best when they're set as far forward as possible. I also want the least possible rod extending out into nowhere, since that can't do anything good, can it?
Author:  grumpy [ Sun Nov 25, 2007 9:38 am ]
Post subject: 
Yup. I fix'em home with polyurethane glue.
Author:  Howard Klepper [ Sun Nov 25, 2007 1:10 pm ]
Post subject: 
Is that a curly maple bridge plate, Robert? If so, it's not a good idea; you would be making the plate more prone to chipping out, as well as less stiff.
Author:  grumpy [ Sun Nov 25, 2007 2:23 pm ]
Post subject: 
Nice catch, Howard.
Author:  Hesh [ Sun Nov 25, 2007 2:57 pm ]
Post subject: 
Love that pink towel Robert my friend- did you get that from Lance at the last swap meet...........
Author:  FishtownMike [ Sun Nov 25, 2007 3:08 pm ]
Post subject: 
martin notches the top and they use a neck block that has an extension to suport the cut top. and truss rod.
Author:  robertD [ Mon Nov 26, 2007 12:48 am ]
Post subject: 
Mario,

I’m very familiar with polyurethane products. However, I’ve never heard of polyurethane glue.
Also, after doing a little more checking, I found, if I do as you suggest, and bring the truss rod all
the way underneath the nut, the extrusion becomes completely within the channel of the neck. So,
that’s what I’ll be doing! Thanks Mario!

Todd,

I think I know now, why those grooves are in the sides of truss rod extrusion. To accept the glue,
so as to make a good bond with the neck? Also, are you suggesting I use GG (Gorilla Glue?) to
set the truss rod?

Hi Howard,

Thanks for chiming in! After reading your post, I went back to look up the receipt. I got it from
AC Woods last December. I was pretty sure I ordered a “Bridge Plate”. But, after looking at the
receipt, I see it says “Maple Head Plate”. I was wondering why I got 2 bridge plates out of it!
I should say that it is well quarter sawn, and very hard. Since I have a second one, that is the
same exact dimensions, would it be wise to test its stiffness? Or, should I replace it altogether?

Hesh! How did you know?

Lance was having a 2 for 1 sale, and I just couldn’t resist! I’m very fond of pink, you know!

Mike,

You are right about the extension. I had to make a choice though. Either cut off some of the neck
block extension, or remove a large portion of the popsicle brace. I chose to cut the neck block.
It seemed the right thing to do, by leaving the brace intact.
Author:  grumpy [ Mon Nov 26, 2007 9:51 am ]
Post subject: 
While I've used a lot of polyurethane glues, I've never used Gorilla Glue(took until just now to figure out what you meant by GG...), so I won't vouch for it.
Author:  Rick Turner [ Mon Nov 26, 2007 10:03 am ]
Post subject: 
The repairman in me wants to know why all the hoops to jump through to hide the truss rod access?   It's a hell of a lot easier to adjust a truss rod from the peghead end of the guitar and see exactly what's going on.   

The worst of all are the SCGC-like arrangements where you need a triple reverse upside down dog leg wrench made out of unobtanium.   

To me this is the triumph of dubious aesthetic concerns over the practicality of an adjustable neck.
Author:  grumpy [ Mon Nov 26, 2007 10:19 am ]
Post subject: 
No hiding here, Rick. Drill a hole in the brace. Reach-in and adjust at will, with the strings in place and tuned to pitch if you wish. The SCGC is a bad example; their's is a exercise in frustration to get to, fr sure, made worse by the odd wrench size....

Why at the body and not at the headstock? Some of us don't like the weakened headstock, and for sure, many of us don't like the look of a truss rod cover or open pocket.
Author:  Rick Turner [ Mon Nov 26, 2007 10:35 am ]
Post subject: 
My pegheads don't break unless they are abused.   And I don't like shoving strings aside just to adjust the T-rod.    With modern truss rods, not much need be removed from the peghead, and with my acoustics, I've got CF running on either side of the truss rod slot.

As a long time repairman, I'm a believer in the "form follows function" aspect of Bauhaus philosophy. I'm not trying to fake traditional instruments, so I'll gladly deal with a truss rod cover to make my instruments easy to adjust. I don't have any more problem with exposed hardware than do any banjo players!
Author:  grumpy [ Mon Nov 26, 2007 10:41 am ]
Post subject: 
So, you'd rather have to pull out a screwdriver to first remove the cover, then adjust the rod, then replace the cover, than simply push two strinsg aside? IF you had to  push the strings aside(I don't even think that is necessary).

Sorry, but I can't see it being simpler... And it is indeed stronger, no matter how you slice it, to not have that pocket out there.

besides, with modern necks, how often do we even adjust the dang things? Once or twice in their life....?

It's moot.
Author:  Rick Turner [ Mon Nov 26, 2007 11:18 am ]
Post subject: 
Coming from the days when five to eight guitars a day came across my repair bench, yes, I'd rather remove a truss rod cover and reach for a wrench.   And I think the argument that the peghead is weaker is specious. It ignores that I've got CF in there and that a scarfed joint doesn't have the same short grain issues and huge hogged out nut scoop as a Gibson-style neck.   Even on our non-CF reinforced Renaissance guitar necks, we now put maple splines across the scarf.   These suckers aren't going to break unless they're severely mis-treated. On our acoustics we put a five layer back strap overlay on the back of the peghead.   You've got to get seriously aggro to bust one.

Author:  grumpy [ Mon Nov 26, 2007 11:37 am ]
Post subject: 
<shrug>
Author:  L. Presnall [ Mon Nov 26, 2007 2:09 pm ]
Post subject: 
[QUOTE=Rick Turner] The worst of all are the SCGC-like arrangements where you need a triple reverse upside down dog leg wrench made out of unobtanium.   

[/QUOTE]

Unobtanium...where can I obtain some o' that?
Author:  robertD [ Mon Nov 26, 2007 11:58 pm ]
Post subject: 
Hi Rick,

I must admit, in my case, it is purely aesthetic. I just like the look of a peghead without a cover.
As for “practicality”, it hasn’t been difficult thus far to adjust through the sound hole. I do see
your point though, as being able to line up your eye on the neck as you’re adjusting the truss rod.

On another note;

Howard has mentioned there may be a problem with the bridge plate.

[QUOTE=Howard Klepper] Is that a curly maple bridge plate, Robert? If so, it's not a good idea; you would be making the plate more prone to chipping out, as well as less stiff.[/QUOTE]

Then I Said,

[QUOTE=robertD]
Thanks for chiming in! After reading your post, I went back to look up the receipt. I got it from
AC Woods last December. I was pretty sure I ordered a “Bridge Plate”. But, after looking at the
receipt, I see it says “Maple Head Plate”. I was wondering why I got 2 bridge plates out of it!
I should say that it is well quarter sawn, and very hard. Since I have a second one, that is the
same exact dimensions, would it be wise to test its stiffness? Or, should I replace it altogether?[/QUOTE]

Is this something I really need to be concerned with?

Robert
Author:  JohnAbercrombie [ Tue Nov 27, 2007 4:49 am ]
Post subject: 
Robert-
No doubt Howard or another 'experienced hand' will come back to help with a suggestion about the bridge plate.
Probably the optimum solution is to remove and replace the plate- you need to get some heat (and moisture?) in there to remove it, and you'll need to be careful not to damage the top while you're at it.
If it were my project, I'd probably laminate a thin layer of hardwood veneer over the existing plate, or just saturate the existing plate with CA in an attempt to toughen it up a bit....then remember not to repeat the mistake on my next guitar.

BTW, be sure to check the tape on the bottom of your trussrod to make sure it is well 'stuck'- if you get epoxy in there your rod won't be adjustable any more!

Cheers
John
Author:  grumpy [ Tue Nov 27, 2007 5:16 am ]
Post subject: 
Just go ahead and use it as-is, but don't do it again <g> It's not optimum(not just the flame, but since it is quarter sawn also), but it's not the end of the world. Another thing I'd drop next time is the little scallop forward of the X braces. Another no-no...
Author:  robertD [ Wed Nov 28, 2007 2:26 am ]
Post subject: 
Hi John,

Thanks for the suggestion, but, I do like the idea of leaving it right where it’s at.

Mario,

I got this top & back, pre-braced at the swap meet. Never gave any thought to whether, or not
the brace pattern was inferior in any way. Would it be wise to remove it?

Thanks again!
Author:  grumpy [ Wed Nov 28, 2007 3:39 am ]
Post subject: 
don't do a thing. Just build it, take notes, and move on to building the next one. Looks like you're assembling the sum of everyone's seconds or sumthing.

Roll your own next time, too. Geeze... They always taste better that way....
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