Hi everybody, greetings from Italy!
I have to refret a '88 SB-1 with a severe bow after the 14th fret, where the truss rod can't help. I shimmed the neck already, but it ended in a rising tongue. I don't want to dress too much the last frets, so I'm looking for a fix to straighten the neck. I've fixed bowed necks before using heat and pressure, but I have to deal with a bi-cut, and I don't think this method will fit. Any advice?
Bi cut bowed neck
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geoff douglas
- Posts: 216
- Joined: Wed Aug 06, 2014 9:50 pm
Re: Bi cut bowed neck
Hi Jenner I too have an issue with a bi-cut bowed neck that can only just be straightened with the truss rod, though with too much tension for my liking. But it still has an issue with rising neck from approximately the 17th fret. For a year now i have contemplated the right/best way to fix this. The more i think about it the more i realise how risky the heating method is and its not worth the risk of buggering it up. I now think the right approach could well be to pull the frets out then tension the truss rod to straighten the majority of the neck. After this im thinking to use emery paper to level the area around the heel then install new frets. Finally i can then adjust the truss rod to attain the correct relief. I might well need to have the slots for the frets deepened in this area but i dont think so as the rise is not too bad, even if i did have to there is plenty of fretboard depth to allow this. Its still a thought in progress so i will be interested to hear your thoughts too.
Dressing the frets alone would work to stop the string buzz in that area however when the neck is looked at length wise i dont want to see the obvious to me neck rise issue, that is why im considering this method to straighten all out. I'm a fussy bugger and want all right, visually and mechanically.
You can look for a previous thread regarding this in the section ( g&l guitars 1980-1991 ) bowed sc-3 neck.
Cheers
Geoff
Dressing the frets alone would work to stop the string buzz in that area however when the neck is looked at length wise i dont want to see the obvious to me neck rise issue, that is why im considering this method to straighten all out. I'm a fussy bugger and want all right, visually and mechanically.
You can look for a previous thread regarding this in the section ( g&l guitars 1980-1991 ) bowed sc-3 neck.
Cheers
Geoff
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Jennar
- Posts: 4
- Joined: Tue Dec 22, 2015 10:58 am
Re: Bi cut bowed neck
Hi, Geoff: thank you for your help! Your thread about the sc-3 bowed neck led me here 
The fretboard planing seems to be the only solution. Press heating a bi-cut neck doesn't sounds like a good idea: a wood shift or worst, a splitting, would be a total disaster. Cold pressing will work only as a temporary fix.
The problem with planing is that the neck is a coated maple one, so there s'no way of doing it without touching the finish (and I'd prefer not), and the fretboard radius is a weird, intermediate one between 7,25" and 9,5", so even find the right radius block will be quite a challenge. If there's a fix that works without heat and dealing with the finish, I'd be glad to know about it... if there's any
The fretboard planing seems to be the only solution. Press heating a bi-cut neck doesn't sounds like a good idea: a wood shift or worst, a splitting, would be a total disaster. Cold pressing will work only as a temporary fix.
The problem with planing is that the neck is a coated maple one, so there s'no way of doing it without touching the finish (and I'd prefer not), and the fretboard radius is a weird, intermediate one between 7,25" and 9,5", so even find the right radius block will be quite a challenge. If there's a fix that works without heat and dealing with the finish, I'd be glad to know about it... if there's any
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geoff douglas
- Posts: 216
- Joined: Wed Aug 06, 2014 9:50 pm
Re: Bi cut bowed neck
Hi Jennar,, Having read the thread mentioned you will know that the majority of thoughts suggest there is not much we can do about this problem. I have talked to a few luthiers here and they say the same. But I cant help but think that for any neck that has been bowed/changed shape there must have been a cause and if that cause can be isolated why cant it be reversed. In my case the frets from 17 to 22 rise but more so on the thick E side. I dont know where the load points for the truss rod are at this end but if it is not central and actually more on the bass E side then maybe the neck could be influenced by this. If the end of the truss rod is effectively acting as a blunt wedge then i can sort of see that the wood above and below that area would slowly be forced outward thus thickening the whole neck to body joint area. I just dont know though whether wood would behave like this or would the truss rod connection just sink in the wood without actually any sideways displacement. If anyone knows the answer to this with maple it would be great to hear from you.
In my case i am going to assume that it is probable so to lessen this effect i first want to reduce the stress needed on the truss rod to achieve the correct neck relief. To do this i need to try to straighten the apparently permanent bow that is in the neck. So now the question is, how did the bow get into the neck. This is what causes me trouble, was it thicker strings that were fitted ( the nut has definitely been filed for bigger strings ) and the truss rod not correctly adjusted and over time the neck settled somehow into this bowed position, was the guitar left in a car for days in high temperatures allowing the wood to soften and the truss rod then to depress into the wood thus allowing the neck to bend maybe staying untouched like that for ages and the neck settled in that bowed position, is it caused by permanent fretboard shrinkage, was it moist wood when constructed that has dried and caused the bow. It's so hard to know what the actual cause was but i am willing to assume that heat somehow was involved.
So with this assumption, considering the neck is still in one piece i cant see why i cannot use heat of the same temperature or more to rectify this issue. Now the question is what temperature is a safe maximum without causing glue breakdown. Without knowing the type of glue used for the bi-cut joint and fretboard joints we will never know the temperature at which the glue will breakdown, if it is known at all that is. If someone knows that answer it would be great to hear from you. We really need a sacrificial neck of the same construction to experiment with to find the "oops to much" temperature but without this we a flying blind so to speak.
Can i ask you Jennar what temperatures have you used to straighten necks without causing damage?. Does anyone else have some temperatures they could safely suggest?. If i assume a guitar is left in a car in North Queensland in summer the temperature can be as high as 65 degrees C if not more.
So the question is, what is the minimum temperature needed to allow Maple wood structure to reform permanently and what for this neck construction is the maximum temperature allowed before glue failure.
All input is gratefully appreciated to hopefully find a solution to this issue,,
Merry Christmas and a Happy New Year to all
Geoff
In my case i am going to assume that it is probable so to lessen this effect i first want to reduce the stress needed on the truss rod to achieve the correct neck relief. To do this i need to try to straighten the apparently permanent bow that is in the neck. So now the question is, how did the bow get into the neck. This is what causes me trouble, was it thicker strings that were fitted ( the nut has definitely been filed for bigger strings ) and the truss rod not correctly adjusted and over time the neck settled somehow into this bowed position, was the guitar left in a car for days in high temperatures allowing the wood to soften and the truss rod then to depress into the wood thus allowing the neck to bend maybe staying untouched like that for ages and the neck settled in that bowed position, is it caused by permanent fretboard shrinkage, was it moist wood when constructed that has dried and caused the bow. It's so hard to know what the actual cause was but i am willing to assume that heat somehow was involved.
So with this assumption, considering the neck is still in one piece i cant see why i cannot use heat of the same temperature or more to rectify this issue. Now the question is what temperature is a safe maximum without causing glue breakdown. Without knowing the type of glue used for the bi-cut joint and fretboard joints we will never know the temperature at which the glue will breakdown, if it is known at all that is. If someone knows that answer it would be great to hear from you. We really need a sacrificial neck of the same construction to experiment with to find the "oops to much" temperature but without this we a flying blind so to speak.
Can i ask you Jennar what temperatures have you used to straighten necks without causing damage?. Does anyone else have some temperatures they could safely suggest?. If i assume a guitar is left in a car in North Queensland in summer the temperature can be as high as 65 degrees C if not more.
So the question is, what is the minimum temperature needed to allow Maple wood structure to reform permanently and what for this neck construction is the maximum temperature allowed before glue failure.
All input is gratefully appreciated to hopefully find a solution to this issue,,
Merry Christmas and a Happy New Year to all
Geoff
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Jennar
- Posts: 4
- Joined: Tue Dec 22, 2015 10:58 am
Re: Bi cut bowed neck
Geoff, we came to the same conclusion: glue's meltdown temperature was my first thought, and the main reason to be really careful about using any heat. I used with other necks a travel iron, changing often position on a metal ruler over the fretboard to check and distribute heat, so I really can't tell anything precise about temperature. It just works. And you're right: we need a good advice from someone who already dealt with this kind of neck and glue, or the planing will be the only way to fix it.
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geoff douglas
- Posts: 216
- Joined: Wed Aug 06, 2014 9:50 pm
Re: Bi cut bowed neck
Hi again Jennar. I doubt any new information will surface, all has been said on this topic i think. We must be the only 2 guys on earth that have ever had a problem with a bi-cut neck so considering the numbers produced that is a blessing i guess. Thank you for your travel iron method for applying the heat, i will google again the topic and see if anything new comes up. I am going bush for a few weeks now and will think a bit more about it whilst away.
Have a merry Christmas mate and all, dont play up too much on New Years night and stay safe.
Geoff
Have a merry Christmas mate and all, dont play up too much on New Years night and stay safe.
Geoff
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KenC
- Posts: 2344
- Joined: Thu Feb 17, 2011 7:18 pm
- Location: None of the above
Re: Bi cut bowed neck
Jennar,
"Ski jump" does show up sometimes on the three-bolt G&Ls, due to incorrect use of the tilt adjustment. That would only affect the last 2-3 frets, though. Have you considered the possibility that the truss rod is maxed out? I haven't experienced this myself, but there have been threads about it here in the past. I remember reading a couple of discussions about adding a washer or two before the truss rod nut. That would be completely reversible, if you wanted to try it before attempting anything more elaborate. You should be able to find those threads if you search on "truss rod". I want to say they were about three years ago.
Also, what type of strings are on the bass? If it's a set with unusually high tension, that could contribute to the problem. The highest tension set I'm currently using is LaBella Original 1954 flats, which required some truss rod tweaking on my '86 SB-1. On the other hand, a couple of years ago I bought an '81 L-2000 that a Guitar Center "expert tech" had diagnosed with an unrepairable back bow. It was ridiculously underpriced, so I took a gamble on it. It turned out that the previous owner had put ultra-light stings on it. I switched to a regular set, and by the time I had it tuned the neck was back to perfect alignment.
Ken
"Ski jump" does show up sometimes on the three-bolt G&Ls, due to incorrect use of the tilt adjustment. That would only affect the last 2-3 frets, though. Have you considered the possibility that the truss rod is maxed out? I haven't experienced this myself, but there have been threads about it here in the past. I remember reading a couple of discussions about adding a washer or two before the truss rod nut. That would be completely reversible, if you wanted to try it before attempting anything more elaborate. You should be able to find those threads if you search on "truss rod". I want to say they were about three years ago.
Also, what type of strings are on the bass? If it's a set with unusually high tension, that could contribute to the problem. The highest tension set I'm currently using is LaBella Original 1954 flats, which required some truss rod tweaking on my '86 SB-1. On the other hand, a couple of years ago I bought an '81 L-2000 that a Guitar Center "expert tech" had diagnosed with an unrepairable back bow. It was ridiculously underpriced, so I took a gamble on it. It turned out that the previous owner had put ultra-light stings on it. I switched to a regular set, and by the time I had it tuned the neck was back to perfect alignment.
Ken
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Jennar
- Posts: 4
- Joined: Tue Dec 22, 2015 10:58 am
Re: Bi cut bowed neck
Thank you for your support, Geoff! I'll keep searching info, I'll write to G&L to ask about the glue. Any good news I'll get will be yours too. Merry Christmas and keep on rockin' !Hi again Jennar. I doubt any new information will surface, all has been said on this topic i think. We must be the only 2 guys on earth that have ever had a problem with a bi-cut neck so considering the numbers produced that is a blessing i guess. Thank you for your travel iron method for applying the heat, i will google again the topic and see if anything new comes up. I am going bush for a few weeks now and will think a bit more about it whilst away.
Have a merry Christmas mate and all, dont play up too much on New Years night and stay safe.
Geoff
Hi, Ken!"Ski jump" does show up sometimes on the three-bolt G&Ls, due to incorrect use of the tilt adjustment. That would only affect the last 2-3 frets, though. Have you considered the possibility that the truss rod is maxed out? I haven't experienced this myself, but there have been threads about it here in the past. I remember reading a couple of discussions about adding a washer or two before the truss rod nut. That would be completely reversible, if you wanted to try it before attempting anything more elaborate. You should be able to find those threads if you search on "truss rod". I want to say they were about three years ago.
Also, what type of strings are on the bass? If it's a set with unusually high tension, that could contribute to the problem. The highest tension set I'm currently using is LaBella Original 1954 flats, which required some truss rod tweaking on my '86 SB-1. On the other hand, a couple of years ago I bought an '81 L-2000 that a Guitar Center "expert tech" had diagnosed with an unrepairable back bow. It was ridiculously underpriced, so I took a gamble on it. It turned out that the previous owner had put ultra-light stings on it. I switched to a regular set, and by the time I had it tuned the neck was back to perfect alignment.
Ken
This neck has a severe up bow, even with completely loose truss rod and no strings. You can set the neck straight with no relief using the truss rod, but it doesn't work on the bend at the 14th fret. A tapered wood shim was for me the only way to get a better action without applying further pressure on the neck heel, worsening the ramp. However, the ski jump on the heel comes from the reset. The heel is straight, but if you consider the 14th fret as a fulcrum, when the shim lowers the first part of the neck, it raises the end creating fret buzz. The truss rod is fairly tight, but not overtighten. I'm using Dunlop Heavy Core 115-55 to play in C standard. They pull a lot, but with this tuning there's no more tension compared to normal strings and standard tuning.
So, we (even Geoff) are looking for a workaround to straighten a bend that the truss rod can't. Press heat looks very dangerous on this particular neck, and planing seems to be at this time the only safe way to fix it.
Merry Christmas and thanks for your help