Neck removal, unusual joint

[Craig Bumgarner]

I need to remove the neck from this old French guitar and I wonder if anyone has any advice for me. I am familiar with the usual approach to neck removal and have done it before. The problem with this one is because of the nature of the joint, there is no gap between the heel and the head block to apply heat to. The heel is butted into a 7mm deep socket in the body and head block, and glued, probably with casein glue. The sides of the heel are a straight sided vee, tapering from 55mm to less than 20mm at the lower end, so I expect the heel will pop loose fairly easily once the glue is broken. The problem is how to get heat to it. Drill some holes down through the joint? A further complication is the sides and back are laminated, so excess heat may start the glue there as well.

Sawing the neck flush off with the body has occurred to me. I can think of several ways to put it back together, but trying to do as little harm as possible of course. Any ideas welcome.

[Alan Carruth]

The full pocket mortise and tenon is a violin style joint. In that application the joint between the button on the back and the neck heel is what holds things in place. Normally this would be glued with hide glue; why do you suspect casein? On a violin the best strategy is sometimes to simply remove the back; once that's off you can get at the sides of the joint, and the end grain doesn't normally present too much of a problem. In this case its hard to say without a better look. Good luck.

[Craig Bumgarner]

The full pocket mortise and tenon is a violin style joint. In that application the joint between the button on the back and the neck heel is what holds things in place. Normally this would be glued with hide glue; why do you suspect casein? On a violin the best strategy is sometimes to simply remove the back; once that's off you can get at the sides of the joint, and the end grain doesn't normally present too much of a problem. In this case its hard to say without a better look. Good luck.

Thanks for the reply, violin joint, that makes sense.

"Button on the back", I'm afraid I don't understand this. What is the "button"?

Casein is suspected because it was commonly used by the Sicilian ex-pat luthiers building in Paris in the 1940s. Glue not cleaned up around the braces is opaque, milky white in appearance which I gather is what casein glue looks like. From what I can gather, casein glue is more resistant to heat and moisture than hide glue. On the other hand the fingerboard came up with no trouble at all, heated with silicon blanket for about 5 minutes and popped it off with hot spatula in 5 more, so maybe I'm exaggerating the difficulty. I'd certainly have a good at it if I could figure out how to apply the heat. Maybe the heat blanket on top, a hot air gun on the heel exterior and slow steady force upward.

Not sure removing the back would gain any better access to the joint than from the top. The neck is set into a head block and if I took the back off, I would expect to see either just the bottom of the head block or bottom of the heel and the neck block if the pocket is cut fully from top to back and covered at the bottom by the binding. Taking the back off would allow access to the head block which could be chopped away and replaced, but I was hoping not to go to that much trouble.

If more pictures would help, please let me know what would be helpful.

[Craig Bumgarner]

Okay, I figured out what a "button" is, or at least I think I have, it's an extension of the back glued to the underside of the heel, right" More of a violin terminology, though I have seen some French guitars done this way as well. I don't think this guitar has a button, see picture below. There is a mahogany heel cap, but this does not appear to be part of the back as the white plastic binding runs under it.

Another thing notable in the picture is the joint between the neck shaft and the lower heel block. This appears to have come loose at some point and was reglued, it feels solid enough now, though not real pretty. The neck heel block is quite rough anyway, so one option might be to cut the heel away and chisel out the remainder in the pocket. This would leave just the neck shaft which could probably be worked out with some hot water and a hot spatula from the top and under side, as well as along the edges. Then a new heel block made, glued to the shaft and the whole thing reinstalled ala the original. Would this be judged a valid repair?

[Alan Carruth]

You're right about what an end button is. This guitar doesn't have one, so removing the back probably wouldn't help. Ah well.

[Mario Proulx]

How about drilling a series of small holes along the neck joint(from the top surface) to weaken the joint, then adding steam? The idea being that the weakened joint will hopefully release before the sides de-laminate. Or if you can find small(1/16"?) bits that are long enough to drill the full length of the heel, you could drill the series of holes the full depth, and pry-off the neck, dry. Once the neck is off, you would convert it to a simple bolt-on butt joint.

[Craig Bumgarner]

Mario, Yes, that all sounds good and I've been thinking along those lines. Alan's mention of violin neck joints caused me to look in to how violin luthiers approach this kind of joint and neck removal. They all seem to saw along side the neck from the outside in to release the sides from the neck and then steam or "break" the neck out with a sharp wrap.

1/16" x 12" (wow) are available from Amazon.com. Not sure if I'm skilled enough to get a 1/16" bit to track an unseen glue line accurately over 3-1/2", but maybe all I have to do is get a couple of "wells" dug to shoot steam into to get it going. Thanks for the ideas.

[Clay Schaeffer]

A couple of days ago I picked up an oscillating multifunction power tool from Harbor Freight (on sale for $15 with coupon) It allows you to saw straight down into a joint like that to a depth of a little over an inch. Some accessory blades allow a plunge depth of over 2 inches. With a homemade blade that depth could probably be increased.
Other , better oscillating tools are available but for occasional use the HF might be O.K. HF tools seem to suffer from quality control issues - some work O.K. for years and I've had others self immolate after little use.

[Steve Senseney]

That joint really does confuse me.

How do you know it is a tapered dovetail?

[Clay Schaeffer]

Many of the old European guitars used that type of joint. Stauffer's adjustable neck was a variation on that joint, combining it with essentially a "bolt on" mechanism. Strictly speaking it is not a tapered dovetail, but perhaps could be called a housed tapered butt joint.

[Craig Bumgarner]

Steve, As Clay says, it is not a dovetail, just a housed (in a shallow pocket), tapered butt joint. As Alan suggests, it is very similar to a violin neck joint. Seems to be holding fine, but somewhat harder to disassemble than most.

Clay, thanks for the thoughts on the oscillating cutting tool. I have such a thing and have thought about just what you propose. Controlling the cut and keep it from straying from a glue line I can't see is the hardest part. As in Mario's idea of drilling deep holes, maybe it doesn't really matter, just relieve enough material, release the sides from the heel with a razor saw, some heat or steam and out it comes.

Oh, for that pocket laser cutting tool, a mini light saber.

[Clay Schaeffer]

"Oh, for that pocket laser cutting tool, a mini light saber."


You'll shoot your eye out! <g>

[Craig Bumgarner]

Darn, first the BB gun, now the mini light saber. I don't have any fun!

[Michael Lewis]

You didn't state the reason for removing the neck. If to re-angle it for better neck angle you may find slipping the back/neck block to be a less destructive procedure. Notice I said MAY be a less destructive procedure.

[Manel Liria]

Maybe you can borrow a saw like this one:

http://www.frets.com/FretsPages/Luthier ... nesaw.html

Just curious, would do the Job?

Manel

[Greg Robinson]

Manel,
I think that is the type of tool (albeit consumer vs medical grade) that Clay mentioned above. They have been available in (expensive) consumer versions for a long time now, and in the last few years very cheap options have been flooding the market too.

[Clay Schaeffer]

The Fein style tool mentioned in frets is what is commonly available on the consumer market. It actually looks a bit more useful as the blades project straight out from the front of the tool. Many of them also mount "detail" sanding pads, so do double duty as a sander. For someone who uses the tool a lot the higher priced versions might make sense. The $15 HF tool for those who only use it infrequently might save a few cents.

[Manel Liria]

Thanks Greg and Clay, I had no idea that those tools were so common and cheap.

Manel

[Craig Bumgarner]

Just a quick one to say I got the neck off in one piece. Used a combination of Alan's violin neck block method, Mario's 1/16" drill and heat. I cut along side the heel to the base of the pocket with a .005" thick razor saw. Drilled some holes down through the base of the pocket and kept working away with a hot spatula. Took about three hours of persuasion, but came apart clean and reusable. An oscillating saw would have been helpful for the first inch or so, but I didn't have one handy. The glue turned out to be hide glue which probably helped.

Thanks for all your help.

[Chris Reed]

Good news! And not casein glue after all, which is further good news.