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  #1  
Old 11-14-2019, 03:45 PM
Mojo21 Mojo21 is offline
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Default Humidity or neck reset

Hi All

Iím a bit worried.

My three guitars were over humidified over summer and all three gained high action. After taking action to control the room humidity (now at 50%) two of the guitars have come back to normal playability. However, one guitar still has a high action.

The problem is that because I hardly play this one guitar I canít remember whether or not the action was high prior to it being exposed to over humidity.

When I place a straight edge on the fingerboard it hits just below the bridge and there is just less than 1/2 inch from the soundboard and bottom E measured at the bridge.

I guess Iím stabbing in the dark asking this question but Iím wondering if it is actually a result of the over humidification then can it take some considerable time for it to come down ó itís been about 3 months since I got the room at the correct humidity.
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Old 11-14-2019, 03:57 PM
redir redir is offline
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3 months is plenty of time. It probably had high action that you forgot about and maybe even got a bit worse. Probably best to take it into your qualified guitar tech to have a look at it.

How much saddle is protruding from the bridge and what is the string action height at the 12th fret for both E and e string?
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Old 11-14-2019, 04:02 PM
Mojo21 Mojo21 is offline
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The action is currently at 2.5 mm (12th fret bottom E). The saddle looks low to me with about 2-3 millimeters left. In my view any lower would compromise break angle.

I tend to like low actions and my other acoustic are 2.2 millimeters.
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Old 11-15-2019, 08:30 AM
redir redir is offline
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I would consider that action to be normal. You definitely have room on 3mm saddle to lower it. Don't forget if you lower the saddle 1mm the the action at the 12th fret will be lowered by half that at .5mm. A 2mm saddle should give you plenty of break. You don't need as much break as you may think. Carruth has done some studies on this that show very shallow break angles impart just as much energy to the top as steep ones.

And if it really bothers you then you could always cut keyhole slots and ramps.

Still it's hard to diagnose stuff like this on the Internet, especially without pics. You might want to take it in to someone who can evaluate it. But by your description I think you would get away with a setup to lower your action forgoing a neck reset.
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Old 11-15-2019, 09:36 AM
Mojo21 Mojo21 is offline
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Thanks very much for the reply ó it sounds encouraging.

Could I ask; If a straight edge placed on the frets and then up to the bridge, am I correct in saying that if the edge of the straight edge falls below the plane of the bridge it is concrete evidence that a reset is due?

According to Frets.com an additional measurement can be taken where you measure the distance between the soundboard and the bottom of the strings at the bridge and if that measurement is less than 1/2 inch then it is good evidence a reset is needed.

Many Thanks.
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Old 11-15-2019, 10:03 AM
RalphH RalphH is offline
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Quote:
Originally Posted by Mojo21 View Post
Thanks very much for the reply — it sounds encouraging.

Could I ask; If a straight edge placed on the frets and then up to the bridge, am I correct in saying that if the edge of the straight edge falls below the plane of the bridge it is concrete evidence that a reset is due?
It depends on where your straight edge is starting and how much relief is in the neck; if it's got a lot of bow it'll lift the nut end of your straight edge and drop the other end. I normally just eye-ball it. Taylor has a half-way useful article here:

https://www.taylorguitars.com/suppor...oms-wet-guitar

Quote:
Originally Posted by Mojo21 View Post
According to Frets.com an additional measurement can be taken where you measure the distance between the soundboard and the bottom of the strings at the bridge and if that measurement is less than 1/2 inch then it is good evidence a reset is needed.

Many Thanks.
I would have thought that was far too much of a broad-brush statement to be making, and I don't agree with it at all; it completely depends on neck angle, fretboard thickness, action and a bunch of other stuff i've not though of. My brand-new (like I literally got it yestreday) Gibson custom shop hummingbird needs a neck reset according to that. It's just under half an inch from strings to soundboard at the bridge. It also has an action of about 2.5mm at the 12th fret, so if I brought it down to you 2.3mm it'd be even "worse".

Honestly you guitar sound fine. I wouldn't bother trying to get that last 0.2mm out of it, but sounds like you easily could.

Last edited by RalphH; 11-15-2019 at 10:14 AM.
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Old 11-15-2019, 11:00 AM
Mojo21 Mojo21 is offline
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I think I agree with you and thanks. I would say that I reckon thereís a bit of scope to bring the saddle down so I may just do it but all things being equal it plays fine, thereís the correct amount of relief in the neck and its intonation is good.

I will just leave it and stop worrying.
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  #8  
Old 11-15-2019, 02:49 PM
RalphH RalphH is offline
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Quote:
Originally Posted by Mojo21 View Post
I think I agree with you and thanks. I would say that I reckon thereís a bit of scope to bring the saddle down so I may just do it but all things being equal it plays fine, thereís the correct amount of relief in the neck and its intonation is good.

I will just leave it and stop worrying.
Great plan. It's easy to worry yourself to death about guitars if you go down that rabbit hole. Play it and be happy
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  #9  
Old 11-15-2019, 03:08 PM
redir redir is offline
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Quote:
Originally Posted by Mojo21 View Post
Thanks very much for the reply — it sounds encouraging.

Could I ask; If a straight edge placed on the frets and then up to the bridge, am I correct in saying that if the edge of the straight edge falls below the plane of the bridge it is concrete evidence that a reset is due?

According to Frets.com an additional measurement can be taken where you measure the distance between the soundboard and the bottom of the strings at the bridge and if that measurement is less than 1/2 inch then it is good evidence a reset is needed.

Many Thanks.
Generally speaking yes on the straight edge. Right down the center of the fretboard to center of saddle. But my mom used to say, rules are made to be broken. So since you have enough room for a setup then don't worry about that now. And all I did was take 1/16th an inch off the string height at the bridge.

The string height over the soundboard at the saddle is a general rule too. I build guitars to that spec but if you need to go 1mm below that then it's fine. I'd prefer not to go higher then that though personally.

I just built a guitar that had what I perceived to be too much bridge rotation. The strings above the soundboard was 1/2 inch on the dot. I built a new bridge and reset the neck angle on it and the bridge rotation settled in at 1.7deg versus the 2.3 it was before. The guitar sounds incredibly better now and I don't have to worry about it's longevity.
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  #10  
Old 11-15-2019, 05:08 PM
John Arnold John Arnold is offline
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It is the height of the strings above the top that is important. Just under 1/2" is fine for most guitars. Regarding saddle height: you only need about 10 degrees of string break angle across the saddle, and I prefer 45 degrees or less, just to assure longevity of the bridge. It sounds like you may have a thick bridge (they do vary). Martin uses three bridge thicknesses to adjust for variances in the neck angle and amount of top belly: 5/16 (thin), 11/32 (standard), and 3/8 (thick). While a 11/32 bridge and a 5/32 saddle may be considered normal, you get the same string height with a 3/8 bridge and a 1/8 saddle, or a 0.400 bridge and a 0.100 saddle.
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  #11  
Old 11-15-2019, 11:20 PM
mirwa mirwa is offline
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One problem i typically come across when repairing, when an instrument has been over humidified or exposed to a wet enviroment for a period of time, permanent alteration to the top has been created.

Just returning it to the correct humidity is sometimes not sufficient enough of a repair, often you need to remove the bridge and reflaten the top, sometimes you need to replace braces.

I have a guitar in at he momment that has been treated similiar to your descriptive, for me to repair as the top has been deformed, i need to remove the bridge, steam and flatten the top, replace one of the internal braces, fit a new bridge and then string it back up

Steve
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