Severe back bow on Modern construction neck, any way to fix it ?

C

Cowbell Fever!

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Dr. Seb, my Burmese Leroy thinks you have a lot of ball*, I mean fortitude!
 

docteurseb

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Spud said:
Dr. Seb, my Burmese Leroy thinks you have a lot of ball*, I mean fortitude!

Thanks but really, as Cagey said it too, in a situation like that there is nothing to loose trying.
The neck would have been completely unusable and unplayable; it was only good in a trash or as a wall ornament.

Trying this procedure bears zero risk at this point, and will be informative to others in the future (not that I want any of you to end up in that same situation).

If it works: I don't end up trashing a $900+ neck (finish included) and save several months ordering/finishing a new one.

If it fails: I loose nothing more (save for the $20 steel rod I had to buy) than if I had trashed it from the get go.
 

Rick

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I use mineral oil on ebony to keep it from drying out.  What did you use?  After your done, to pull the cracks together in the ebony I've used super glue. (Of course, clean it first with naptha to sop up the mineral oil.) Comes out perfect.  I called Dan Erlwine's shop many moons ago, and his assistant, I think it was Eric told me, and it came out great.
 

triple jim

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DrSeb said:
The primary concern is whether the 3rd session will finally put a proper forward bow and rectify the uneven slope at the heel.
The progress you're making is very encouraging, but I would think you may need to do a fret level if there's any unevenness or to restore fall-away, etc.
 

docteurseb

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Triple Jim said:
DrSeb said:
The primary concern is whether the 3rd session will finally put a proper forward bow and rectify the uneven slope at the heel.
The progress you're making is very encouraging, but I would think you may need to do a fret level if there's any unevenness or to restore fall-away, etc.

Agreed. If it ends up being usable I fully anticipate badly needing a fret leveling given the amount of trauma it's been subjected to over the past week alone.

I would probably wait a while though to let it settle in once strung up.
 

docteurseb

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rick2 said:
I use mineral oil on ebony to keep it from drying out.  What did you use?.

F-One Oil is what I had handy, and it seemed to have helped for the 3 baking session. I don't see additional cracks but the rod is masking the center of the fingerboard, we'll see. I had already infused thing superglue into those cracks before getting started, so that may have helped too.
 

triple jim

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DrSeb said:
Agreed. If it ends up being usable I fully anticipate badly needing a fret leveling given the amount of trauma it's been subjected to over the past week alone.

I would probably wait a while though to let it settle in once strung up.
That sounds like a very good plan.
 

docteurseb

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I finally unclamped it after a week.
While there is possibly still a very minor slope change starting around the 15th fret (beginning of heel), it so minimal now that I don't think it's worth trying to do anything about it.

No additional cracks that I can see, no additional side effects from the 3rd baking session.
I'm relatively optimistic the neck is saved and will be fully functional without another round into the sauna.

Thanks a lot Cagey for the interesting procedure.
I just added a note to your thread to advise conditioning the fingerboard before starting each session (I tend to read quickly and may not have seen that advice if it was already mentioned).
 
C

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Did we learn a lesson? Steaming wood is how they bend wood to make barrels.
 

docteurseb

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Spud said:
Did we learn a lesson? Steaming wood is how they bend wood to make barrels.

Having tried the technique successfully countless times to make dings disappear I would not necessarily have anticipated such a dramatic effect on the neck.

In reality, cleaning and blending the finish along the fingerboard edges from the pro shop was so grueling (two afternoons, basically) that fixing tool marks left when removing the superglued masking tape off the fingerboard was the only concern on my mind, without take any time to think about unintended consequences of injecting water into thin and slotted piece of wood.

Had the streaming been localized to just a fret position or two, it may not have moved at all.
The problem is I effectively ended up steaming so many spots that the entire fingerboard was steamed; the end result in retrospect is not all that surprising (though the amount of back bow is still remarkable)

I still would not attempt the dent removal method on a fingerboard, even if it's just one spot.
 

Cagey

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Necks and steam don't go together well. Consider that builders spend months of time "seasoning" the wood to get it to just the right moisture content before they cut/machine it into a product. Some hardwoods are more prone to move based on moisture content than others, with Maple probably being the worst. That stuff seems to have a mind of its own sometimes, and is why Warmoth won't warrant a Maple neck that doesn't have a hard finish, unless it's been torrified.

Also, tension/pressure rarely move the wood the way you'd like, either. Consider that a strung-up guitar has roughly 100lbs of string tension on it 24/7.

 
C

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TBurst Std said:
Spud said:
Did we learn a lesson? Steaming wood is how they bend wood to make barrels.
The art of cooperage.
And cooperage and its most famous industry which it supplies is a blessing! (disclaimer, not all barrel contents are created equal.)
 

docteurseb

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On closer look though, it is definitely a bit warped (back of the headstock not parallel to the heel when sitting on a flat surface).
I might quickly install tuners and a rough nut to see how bad that looks/feels in practice when strung up.

 

Cagey

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As long as the fretboard isn't twisted, you can always bake it again to build in more/less relief. A known straightedge (a machinist-grade tool, not just a ruler - they can be pricey, so check ebay first before throwing $100 at Starrett or StewMac) and a fret rocker will reveal a twist.
 

docteurseb

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Cagey said:
As long as the fretboard isn't twisted, you can always bake it again to build in more/less relief. A known straightedge (a machinist-grade tool, not just a ruler - they can be pricey, so check ebay first before throwing $100 at Starrett or StewMac) and a fret rocker will reveal a twist.

Twisted a bit, rather than warped, is really what I meant.

Edited : just strung it up briefly, if there is a twist it must be minimal.

But there is also barely enough relief IMO under tension, and the weird slope past the heel is still there: quite straight from 22nd to 15th  frets, and then forward bow/slow until the 1st fret or so.

Adding relief with a 4th session is fine, but I'm not sure how to tackle that slope while doing it.

I could concentrate on that heel area, though it's not clear where I'd put the clamps and gauges exactly; but if the remainder of the neck isn't clamped it probably will move unpredictably.

Feels like I would maybe need more clamps and feeler gauges positioned in several places rather than just 2; and the gauges would probably need to be of specific thickness and positioned strategically so the neck's bow ends up looking like a bow. Or maybe the usual two clamps would suffice but with additional feeler gauges around the heel.
 

electric__steve

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What are you clamping against?  Is it perfectly flat and rigid?  I’d consider clamping the neck perfectly flat, with a LOT of clamps, against something very stiff,bake, and then see how much rebound you get. 

https://www.homedepot.com/p/Everbilt-2-in-x-36-in-Plain-Steel-C-Channel-Bar-with-1-8-in-Thick-801217/204225748    Not sure if stock like this is perfectly flat, I’d check with a straightedge.

Also, when the neck is pretty close but not quite perfect, you could just level and crown the frets to finish it off.
 
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