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Head (blocks) are gonna roll!
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=22054		 Page 1 of 1
Author:  L. Presnall [ Tue Apr 21, 2009 8:24 am ]
Post subject:  Head (blocks) are gonna roll!
Okay, so I had a guitar of Canadian manufacture come into my shop (actually a guy brought it in) and asked about a neck "adjustment"...from what I can see everything is geometrically correct with the guitar...ie, the nut action (maybe just a touch high), straight neck, level frets, no obvious "hump" at the body, just under 3/16" saddle showing, and strings 3/32" at 12th fret (low E) and 1/2" above the soundboard at the front of the bridge...and a straight edge on the frets lands right on top of the bridge...but...when I look at the side of the neck (playing position) the action seems high down the neck from the nut to the last fret! I know it's not relief (the neck's straight)...so I'm wondering is this the "headblock rolling forward" that I've heard about but never witnessed? I've read where the "back stretches" and the "upper bout comes forward" and the "soundhole dips" and the result is the fingerboard aiming too low at the bridge...but if so, how does one prevent this in the building stages? I never worried before, but it got me thinking..."I'm building these things from the ground (actually, the bench) up...I can do anything here I want, so let's make sure I build a cannon that won't fold up...but, I still want tone of course...so, some of you repair guys and those with a thousand guitars built, what say ye? Is this phenomenon real or like just a tabloid "alien, flesh-eating zombie virus"? Have you seen it? How'd you deal with it? How do you ensure it doesn't happen to you?
Author:  TonyKarol [ Tue Apr 21, 2009 8:35 am ]
Post subject:  Re: Head (blocks) are gonna roll!
So you measure and its fine, but you "see" something different ??? ... then you arent "seeing" it correctly. The rulers dont lie .... unless they are crooked.

Ummm ... so what is the issue ????
Author:  Mark Kozlowicz [ Tue Apr 21, 2009 9:40 am ]
Post subject:  Re: Head (blocks) are gonna roll!
is the neck angle correct? If you're not seeing deformation of the top, I don't think it has to do with the neck block. I had a guitar in the shop with this issue, the neck block came unglued from the sides. The sides deformed and the top was cracked and moved forward on either side of the FB extension. If it was really the fault of the neck block, you would certainly know. That being said, I didn't know that the block had come unglued until I did a neck reset on the guitar. The guitar was 50+ years old, so it wasn't unusual to see that sort of deformation.
Author:  L. Presnall [ Tue Apr 21, 2009 11:38 am ]
Post subject:  Re: Head (blocks) are gonna roll!
TonyKarol wrote:
So you measure and its fine, but you "see" something different ??? ... then you arent "seeing" it correctly. The rulers dont lie .... unless they are crooked.

Ummm ... so what is the issue ????



Wow Tony, I know that reading a post it's possible to "read into" it so I'm trying to be gracious here...but, I've been to college as they say, and what I'm seeing is what I'm seeing! :shock: The ruler is, in fact, telling the truth as you say...but, the fingerboard is telling me that the action is high along it's length...it just happens to be correct at the 12th and the front of the bridge...the issue is...that frets 3,5,7, and 9 have what seems to be "high" action...that's what's vexing me...I agree with you that it "should" be okay, but the feel is the feel...and since the guy brought the guitar to me, I'm not alone in what I see and feel...the question I posed was in regards to this...not that I was confused about what I measured! My day job is in absolute absolutes, so I'm on familiar ground with what can be quantified that way, but this guitar thing as you know. is science with no small amount of "art" and "feel" thrown in to make one guitar special over another...if anyone has an answer to my question, I'm all ears...

Thanks,

Larry
Author:  L. Presnall [ Tue Apr 21, 2009 1:09 pm ]
Post subject:  Re: Head (blocks) are gonna roll!
Hi Todd,

No, the board's straight...my first "off-the-cuff" idea was that the neck had just been pulled into relief by string tension, but that's not it...nor is the guitar dry...no fret ends sticking out past the fb sides or low top or anything like that...
Author:  TonyKarol [ Tue Apr 21, 2009 2:12 pm ]
Post subject:  Re: Head (blocks) are gonna roll!
Ok, I just didnt see an issue per se .. so what is the action measure at 3/5/7/9 then ??? Worse than 3/32 ???? - if so, how can the board be straight unless the nut is really bad ???

sorry, but I am still struggling with this ....
Author:  bluescreek [ Tue Apr 21, 2009 4:04 pm ]
Post subject:  Re: Head (blocks) are gonna roll!
You identified your problem when you said the neck was straight and the action was where it was at. You want to have relief in the neck. You want to have about .008 at the 7th fret with the 1st and 12 fret capoed.
With a straight neck and what you measured your geometry is off. With proper relief your action would be high so you would need to establish the relief then set the action height. This will lower the saddle but make the guitar more playable.
You may have incorrect neck angle and this will make things difficult to set up without resetting the neck.
Author:  Mike Mahar [ Tue Apr 21, 2009 5:21 pm ]
Post subject:  Re: Head (blocks) are gonna roll!
I had something similar to this happen to me. The measures action at the bridge and 12th fret were good for the E strings but the guitar felt like the action was too high when you played it. The problem turned out to be that the arc of the saddle was too much greater than the fretboard radius and when I measured the 12th fret height of the D and G strings I found that they were way too high. Reshaping the saddle fixed it up.

Your description does not exactly match this problem but I agree with Tony that it is hard to figure out what is going on from your description. You say that a straight edge just rests on the top of the bridge. How long is the straight edge? Does it extend up to 5th or 3 fret? If so it is in contact with the frets in between? If not, how big is the gap? There has to be some physical, measurable, dimension that can explain the problem.
Author:  L. Presnall [ Tue Apr 21, 2009 6:50 pm ]
Post subject:  Re: Head (blocks) are gonna roll!
Mike, I agree...my mind says that if there's something out of the norm, then it can be id'd and measured...maybe it's so simple that I'm missing it...like calling the Maytag repairman who finds the washing machine is unplugged... :shock: It looks like everything was done properly with the guitar tho...I'm gonna go give it another look this evening since I've had some time away from it...maybe a fresh perspective when I go back to it...
Author:  L. Presnall [ Tue Apr 21, 2009 6:53 pm ]
Post subject:  Re: Head (blocks) are gonna roll!
TonyKarol wrote:
Ok, I just didnt see an issue per se .. so what is the action measure at 3/5/7/9 then ??? Worse than 3/32 ???? - if so, how can the board be straight unless the nut is really bad ???

sorry, but I am still struggling with this ....


Tony, sorry, I missed this post...I'll measure the action at the 3-9th fret and see if I can describe more accurately what's what here...unless it's a combination of nut/saddle then I'm at a loss...like I told Mike, it is probably so obvious that I'm missing it in search of a more "exotic" problem...
Author:  L. Presnall [ Tue Apr 21, 2009 7:06 pm ]
Post subject:  Re: Head (blocks) are gonna roll!
Okay, the actions are as follows:

1st - 1/32
3rd - 3/64
5th - 3/64 + (not quite 4, but just barely over 3/64)
7th - 5/64
9th - 5/64 +
12th - 3/32

There's 3/16" of saddle showing at the top of the radius between the D and G strings and the strings are 1/2" off the top of the soundboard at the front of the bridge...the relief at frets 5-7 may be just a bit too much and the nut action appears to be just barely too high (testing by the "fret at one and press at three" method)...and the straight edge I used for neck angle went from the nut to the bridge...
Author:  TonyKarol [ Tue Apr 21, 2009 7:21 pm ]
Post subject:  Re: Head (blocks) are gonna roll!
OK ...

so.. I see the action as pretty good, at least IMO ... if the neck is straight (as you mention earlier), then how can there be too much relief in the neck ??? - seems contradicatory ....

I take it you mean hold between 2/3, tap the string at 1 to see the nut action .. the E/B should barely bounce, the rest progressively more, with the low E showing some bounce, but not much - if you feeler gauge it, likely around 20-22 thou at most (I like it around 17-18 thou at 1)

Do you have an SM action gauge .. if not, next order, get one. You will never guess at action again. Its way easy to see what the action is on any string, any fret .. accurately.

I just had a 68 LP gold top in, the action was lower on the DG than the two Es .... the non original saddle had collapsed some ... new Gotoh fixed her up good. Easy to read with the action gauge why the guitar was buzzing out at 10-12 on the D/G .. then you see the bridge is concave !!!!
Author:  L. Presnall [ Tue Apr 21, 2009 7:45 pm ]
Post subject:  Re: Head (blocks) are gonna roll!
I heard the SM action gauge was a good thing...guess that'll get on the next order indeed...the thing about this guitar is that the brand is known for being pretty well made and the owner says nothing's been replaced (nut or saddle anyway)...it just has a weird, "the action is too high down the fingerboard" kind of feel...as far as relief, I've mislaid my feeler gauges and rather than look for them for half an hour tonight, I just eyeballed it...there's a little more bounce than I keep in my necks, but only a couple thousands...thanks for all the input Tony and everyone who responded...it'll likely be that I tweak the truss rod a bit, and lower the nut action a tad and give it back no charge and see if he's happy...maybe a psychological boost more than anything...like the old story about Hendrix's guitar tech bringing out 10 phase shifters before finally giving him the one he started with...and Hendrix says, "Well, why didn't you bring me THIS one FIRST"?! :D
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