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neck angle change after fretting
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Author:  rogueguit [ Thu Dec 13, 2007 3:37 pm ]
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Folks, I haven't done a forum thing in a long time... think I was carrying on about the '69 Mets the last time I did a forum... I'm building my 2nd guitar. 000-28 24.9 scale. Things have gone well... I think, til now. The body is set to go, the neck is shaped and ready, preliminary checks of the neck set are good. bare neck is flush to the soundboard and I got 9 mm clearance at the bridge position with the unfretted fretboard clamped to the neck and bolted to the body. But now that I have fretted the fret board and glued it to the neck a straight edge no longer rests along all the frets evenly. A straight edge sets on the first four frets and runs off way high of the other frets. When I place a straight edge on the 5-18 frets it runs true and contacts the unglued bridge at its proper location just grazing the top of the bridge. Do I need to crank on the truss rod to even things up?Any insight would be greatly appreciated... Greg
Author:  BlackHeart [ Thu Dec 13, 2007 4:09 pm ]
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Have you leveled the frets?, And I think there is supposed to be a dip in there somewhere.
Author:  Ken Jones [ Thu Dec 13, 2007 4:16 pm ]
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Hey Greg --


Welcome to the forum. I'm fairly new here, and still new to guitar building -- I'm starting the finishing process on my second and third. My first was a StewMac kit, so these two have been a huge learning experience. My point is, I'm no authority, but I've just gone through these same issues that you're facing. In fact, I got a little of the same thing, which was in fact remedied by tensioning the truss rod. My understanding is that you want it a bit under tension anyway. I think I read that many builders like a slight (1/32) relief in the neck.


I am thinking though, that when you tension the trussrod, your straightedge may then hit the bridge a little low, in which case there may be a need for a slight neck angle adjustment at the heel.


I'm sure some more knowledgable folks will chime in on this soon.


Ken
Author:  JohnAbercrombie [ Thu Dec 13, 2007 5:59 pm ]
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Hi, rogueguit...
(Real names are always handy things to use here-'don't be a stranger' as folks say...)

It sounds like you have a bit of 'backbow' in your neck right now.
Assuming you used a water-based glue (titebond or similar) to glue down your fretboard, the first step might be to hang up the guitar for a week or so in your 40-50% humidity area and see what happens.
Cranking on the trussrod will put more backbow in the neck and isn't the step to use now, I think.

Hopefully the experts will come along and give you some advice on this.

Cheers
John
Author:  Hesh [ Thu Dec 13, 2007 11:49 pm ]
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Welcome to the forum!!!  It would be helpful to us if you would at least provide a first name so that those of us who wish to treat you with respect may do so.  You can enter a name in your profile or after your posts.

Yep - good old back bow has visited you my friend.  Back bow can occur once the fret board is fretted because the tangs of the frets are now pressing the two sides of the fretboard away.  Have enough frets and you have back bow. 

Pressed frets tend to create much less back bow in my experience (and tests) then hammered frets.  But as you know some frets are in locations that just have to be hammered.  And back bow can be more severe on the fret board extension because there are more frets per inch and the extension, until the neck is installed, is unsupported by the neck.

In addition, water based glues like Titebond, HHG, Fish glue can cause back bow too where epoxy is a better choice for attaching the fret board to the neck.

What I would do now is attach the neck to the guitar temporally and use the truss rod to get all the hack bow that you can out of the mix.  Then level the frets with a long fret leveling beam (Stew-Mac has an excellent one).  If you try to level the frets prior to adjusting the truss rod some of the high frets may be leveled away to nearly nothing.

Again - welcome to the OLF!!!
Author:  TRein [ Fri Dec 14, 2007 1:07 am ]
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Frets can exert a tremendous wedging effect on a neck and easily push a back bow of .030" into the neck. Water based glues can do the same. It sounds more like frets to me since you already had the neck shaped and the fretboard levelled.
I solved the problem by getting the Stew Mac Fret Barber and pre-tensioning the rod prior to fretting. You will have to experiment with how much tang to take off depending on the density of your fretboard. I level the fingerboard before fretting, then tension the rod to bow the neck back about .014", level again (taking out the hump in the middle), relax the rod and then fret. The frets still push the neck back almost flat, but the string tension pulls the right amount of relief back into the neck.
Author:  WaddyThomson [ Fri Dec 14, 2007 3:00 am ]
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Welcome to OLF, GREG!  Thanks for giving us your name in your first post.  It is very helpful to know how to address you for all the help you'll get here.  I know nothing, so I won't try to tell you anything!  
Author:  Barry Daniels [ Fri Dec 14, 2007 3:21 am ]
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There is a basic question that no one has asked yet. Are you using a dual action truss rod or a single action?

How much backbow are we talking about? Put a feeler guage on there and measure the gap at the first fret.
Author:  Hesh [ Fri Dec 14, 2007 4:22 am ]
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[QUOTE=WaddyT]Welcome to OLF, GREG!  Thanks for giving us your name in your first post.  It is very helpful to know how to address you for all the help you'll get here.  I know nothing, so I won't try to tell you anything!  
[/QUOTE]

Duuuuugh.......  Sorry Greg I missed that you did post your name - my apologies.

Waddy you can drink paddy water........
Author:  rogueguit [ Fri Dec 14, 2007 4:53 am ]
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This is awesome... Every time I turn around I'm pondering some aspect of building. This is my second guitar, the first being a kit from Stew. Mac. Ramping up the difficulty a little this time. Got the goods from LMI. Very happy. Also happy with their tech support but now I have this resource also! I wonder if I'll ever build a guitar without three different books at hand and my phone with the speed dial set to Lmi's 800 number. I tried to register under my name Greg G. but that was already taken so I'll just leave it at roguegit for now. Between my own guitar fetish and Mandolin my son and daughter play so I have a built in excuse for at least two more axes and a mando to build. I'm a 49 yr old Wisconsin Dairy farmer. It'll be 15 below tonight. Alright now you know more about me than you wanted to. Anyway I will be studying these replies and  getting back at that neck soon. Two more questions. Is it o.k. to take the unfinished body of this guitar out into an unheated shop to do the final sandings before finishing? It'll probably be 15 or 20 degrees out there this evening. Lastly, any opinions on water based finishes. I dread stinking up the house with the aerosol lacquer products from Stew Mac. Although I was really happy with the results. Oh, and I would be brushing it on. Any thoughts. Thanks, Greg.
Author:  JohnAbercrombie [ Fri Dec 14, 2007 5:25 am ]
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Greg-
Sorry I missed your name at the end of your first post- not paying attention, I guess!

Welcome to the OLF!

About levelling the frets on your guitar-If things don't 'settle down' on their own (or with the use of a double-action trussrod, if you've installed one), I'd advise pulling the frets and re-levelling the fingerboard once it is glued on to the body. If you are using a single-acting trussrod, it's common to crank in a bit of tension before levelling the board- then you have the option of releasing the rod to correct a bit of backbow later, if necessary.
Fretting after the neck is glued on is more trouble. However, dealing with a neck/fingerboard curvature issue by filing down the frets is not the way to go-it's probably more work in the end (re-crowning, etc) and you will never be happy with the result- when you re-fret you will do it right anyway- might as well get it over with now.

An unheated shop will not harm your guitar while sanding - the RH out there is probably OK.
You are correct about not spraying lacquer in the house- this is a bad idea all around. French polish is a good option, if you are interested in learning that, and are not set on the 'dipped in plastic' look for your guitars.
Varnish is another good-sounding option, though (like some of the waterborne finishes) you have to be careful about 'witness lines' when levelling and polishing.
Cheers

John
Author:  Michael Dale Payne [ Fri Dec 14, 2007 6:30 am ]
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Greg John is right here. One of the building with a double acting truss rod is that you can impart a bit of relief during fretting the let the tension off as needed prior to leveling the frets.

If things don't settle out for you an other options is to remove the frets. mount and clue up the neck and fretboard to the body, re level the fretboard to the proper plane of fretboard/bridge relation ship with one of Stewmac's 18" aluminum radius sanding blocks taking care to work only the area that needs lowered till the sanding block contacts the fretboard evenly everywhere and on plane. Then re fret, fret level and so forth.
Author:  rogueguit [ Fri Dec 14, 2007 12:40 pm ]
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Here's a bit more info on the situation. The truss rod is accessed at the peghead end. With the peghead touching my gut a clockwise turn bows  the rod into the fretboard at its mid point. A ccw turn bows the rod into the bottom of the neck at its mid point. I assume this makes it a dual action truss rod ( yes I am a rookie) I also assume I want to give it the ccw turn to correct the back bow. I have 18 frets installed on the board. A straight edge placed on the 18th fret rests level up to fret 10. then is above frets 9 through1. At fret one there is 1 mm. gap between the top of the fret and the bottom of the straight edge. How much turning can one do on the truss rod? Should I turn a bit then wait and give it a little more? Just as an added piece of info a straight edge placed on fret 1 rests on fret2 before skating high of the remaining frets. Does that seem odd? I'm not against refretting but would it work to lay the fretboard fret side down on a piece of soft pine and clamp the end thats free of the neck down and then gradually exert clamping force to the other end and adjusting the truss rod also (like over a period of a week or two) ???  Thanks again for the advice. Greg
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