Andy FitzGibbon has mentioned that cutout under the fingerboard before. He has likely seen the inside of more of these than anyone since the original workers made them.

I glue sandpaper to blocks of varying size. The smallest is perhaps an inch long, the longest are 6" to 8" or 10".

I use a really good straightedge, locate the most obvious high spots, knock them down, and keep repeating until I am satisfied. Sometimes a small bump has to be started off with the 1" block, occasionally across the grain. When I feel that I am close, I use a cabinet scraper to insure that the board is horizontally level, then come back with a long block. Then I re-check everything and spot level any remaining high spots, then go over it once more with the scraper and long block. Then check once more, and when everything looks pretty good, I clean it up once more with 220 on a long block, then clean with alcohol before glueing.

Some folks use long sanding beams. They haven't worked well for me.
Different people have different preferences for their weapons of choice.
Remember that it is sometimes easier to sand small areas accurately than it is to accurately sand a large area.

The channel may have been cut to make the original levelling process easier.

The neck is one piece. What you're seeing is a channel that was routed at the factory for a maple reinforcement. For some reason, the majority that I've disassembled never had the reinforcement installed.

Even more strangely, some have short sections of maple installed at the nut, heel, and 5th peg area, with the rest left empty... basically, wherever you'd see the maple once the fingerboard was glued on. No explanation that I've come up with for that makes much sense at all. Maybe an employee was pocketing the small strips of maple for kindling at home?

That's great. Thank you for the detailed explanation. I'm deathly gonna go with sanding or planing.
 

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Originally posted by rcc56

I glue sandpaper to blocks of varying size. The smallest is perhaps an inch long, the longest are 6" to 8" or 10".

I use a really good straightedge, locate the most obvious high spots, knock them down, and keep repeating until I am satisfied. Sometimes a small bump has to be started off with the 1" block, occasionally across the grain. When I feel that I am close, I use a cabinet scraper to insure that the board is horizontally level, then come back with a long block. Then I re-check everything and spot level any remaining high spots, then go over it once more with the scraper and long block. Then check once more, and when everything looks pretty good, I clean it up once more with 220 on a long block, then clean with alcohol before glueing.

Some folks use long sanding beams. They haven't worked well for me.
Different people have different preferences for their weapons of choice.
Remember that it is sometimes easier to sand small areas accurately than it is to accurately sand a large area.

The channel may have been cut to make the original levelling process easier.

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That's interesting. Maybe I will actually install the maple reinforcement. What are your thoughts on installing a titanium rod in the in the channel. Is that worthwhile? My goal is to keep the sound as close to the original instrument as possible. Not sure if the titanium rod would affect that in any way, or do any good since it's already came this far without any vertical bowing. 

The other question I hope you don't mind answering. Should I replace the Ebony board with the exact Thickness. Somebody was saying I should install a thicker Ebony board. What do you think? it's an AC Fairbanks special number 1. The fingerboard was pretty thin to begin with. 

Thanks so much appreciate you replying to my post. Cheers
 

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Originally posted by Andy FitzGibbon

The neck is one piece. What you're seeing is a channel that was routed at the factory for a maple reinforcement. For some reason, the majority that I've disassembled never had the reinforcement installed.

Even more strangely, some have short sections of maple installed at the nut, heel, and 5th peg area, with the rest left empty... basically, wherever you'd see the maple once the fingerboard was glued on. No explanation that I've come up with for that makes much sense at all. Maybe an employee was pocketing the small strips of maple for kindling at home?

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Me, if I was going to fill it, I would probably choose maple or ebony rather than a metal rod.
A thicker fingerboard would increase the structural soundness of the neck. I might choose somewhere around 1/8" to 5/32", not less, and not much more.

How about a carbon fiber filler? For the warping, perhaps steaming it, then clamping to a flat surface for several days.

Very interesting. How wide and deep is this channel? It looks to be only about 1/8" wide. It would be interesting to know how it was made. Are the ends of the channel the same depth as the rest...or do they taper off? Basically, is it routed or cut with a circular saw?

In my mind, a thin reinforcement strip of the same wood would be silly. Even a more dense or stiffer species would offer minimal reinforcement in such a thin cross section. My Windsor #1's Walnut neck is hollow from around the first fret to the heel (which features a bell, like a trumpet). There are slots along the length of the neck under the fretboard and some of the inlay is pierced into the hollow. It's over 120 yrs old and still straight. Who needs reinforcement? 

Pure speculation, but I would see this slot as part of processing, a feature used in conjunction with a jig or fixture and then filled (or not) after the jig/fixture's work was done. A strip of metal (or wood) inserted into that slot would provide side-to-side location and perhaps a clamping method. If it is a routed feature, it could provide longitudinal location as well. Once you have it located, you're set for any pattern work you need to do. Headstock shape patterns especially were likely pattern-routed.

Be careful adding thickness to the fretboard. The cross-section of the neck can get too thick, feeling clunky. Also, the fretted surface can end up too tall, requiring a taller bridge, etc. If you cut away the neck to keep the fretted surface at the original height (with the thicker fretboard), other issues can arise. I've seen this done improperly and the result was a very narrow neck. 

IOW, think ahead and be careful.

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Originally posted by lfinch

Getting into a restoration project. First time trying a restore so I’m going slow. I’m replacing the ebonized fingerboard because it was cracking and falling apart. Before I can put on a new ebony fingerboard I need to correct some warping in the neck. I do not see any Bowing in it, but When you look down the neck you can see small hills and valleys from left to right. that’s what I’m calling warping. What is the best way to correct the this. I’m looking to try a straightening jig as suggested in Larry Sanders complete Banjo Repair Books. I know you can sand it as well. Not sure which one is best if there’s something I’m not thinking of. I was planning on putting a thicker ebony fingerboard on it, so I might end up t sanding it down anyways. I haven’t gotten that far yet. Like I said moving slowly and carefully.

When I removed the fingerboard there was a man-made slit down the middle. It’s too even and straight to be a natural fracture of any kind, which leads me to believe it was made out of two pieces of wood and over the years they’re just coming apart? Should I fill this in leave it alone?

Thanks so much appreciate any feedback for a noob ??

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I've restored one of these before. Mine also has that slit. I thought it was a glue reservoir, but I might be wrong. It's definitely one piece of wood. These were definitely cheaper catalog banjos. There still pretty cool though. 
i put a thicker rosewood fingerboard on the one I repaired. In hindsight, I wish I'd have gone much thinner, but my brother likes the banjo, so I left it as is and gave it to him. In fact it's the first banjo in which I ever attempted a repair job.

 Blaine

The "small hills and valleys" are probably not warpage. I would suspect the high spots are glue residue and even some thin bits of wood. Any glue needs to be removed; new glue is usually incompatible with old types. Sanding seems the best bet for this.

I would simply leave the slot alone. I think, like Marc, that the groove was a factory alignment feature. I've seen numerous "useless" slots, holes, etc. on old factory made furniture, clock cases, and piano case parts that had been used in making those items or to move them around a shop.

Before you sand the fingerboard and peghead areas level, put on wet paper towels on those surfaces to soften the hide glue. After about an hour of moisture, the leftover hide glue and ebonized wood will be easy to scrape off when dry it will be much easier to level.

Bob Smakula

quote:

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Originally posted by Bob Smakula

Before you sand the fingerboard and peghead areas level, put on wet paper towels on those surfaces to soften the hide glue. After about an hour of moisture, the leftover hide glue and ebonized wood will be easy to scrape off when dry it will be much easier to level.

Bob Smakula

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Good advice from Bob Smakula, the only thing I would add is use warm wet paper towels.

Dave1climber

Actually I prefer cold water when dissolving hide glue. Put on the wet paper towels, then ignore for an hour or so and the glue scrapes off nicely.

Bob Smakula

Once the glue residue is gone, you can use "shooting-sticks" to check for warp or twist. These are laid on the fingerboard plane. The you sight down the neck from either end. If the sticks are in the same horizontal plane, you can then check for any bow in the longitudinal plane. I would avoid any titanium rod. If I use any reinforcement, I would use maple or ebony.

Also, vinegar acts as a solvent for hide glue. I learned this working on antique phonographs. It can be injected under loose veneer.

quote:

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Originally posted by Bob Smakula

Dave1climber

Actually I prefer cold water when dissolving hide glue. Put on the wet paper towels, then ignore for an hour or so and the glue scrapes off nicely.

Bob Smakula

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Bob Smakula

With your greater experience than I with hide glue, I am wondering why cold water and not warm?

Water is the least invasive if you're going to use a solvent. Sometimes it works, sometimes it doesn't. I've encountered globs of glue in old violins that would only yield to mechanical means.

I usually try to at least knock the old glue down with a scraper before applying any liquids. Sometimes, the scraper is enough.

I've also used alcohol for clean up, but it needs to be kept away from finished surfaces.

I've tried vinegar, too. It does work, but it also caused some discoloration. I don't know whether this was caused by the vinegar alone, or whether it was caused by the use of a metal lifting tool in conjunction with the vinegar.
Whatever the exact cause, I would keep it away from any public surfaces that will be visible upon reassembly. I would also keep it away from any finished surfaces.

The scraper referred to is a cabinet scraper with a micro edge on it. Learn this and how to sharpen them, it'll help immensely

Some prefer a vinegar solution rather than full vinegar.

No metal is necessary.

I had ( I regret letting this go), had an SS Stewart Mandolin banjo neck, it was still intact.

Using the fingerboard and peghead cover or top cap as reinforcing structures, the neck was still straight. I had to look around and find a Stromberg neck, not the same.