Neck joint on Martin bowlback?

Searching the archives suggests this might be an "unknown", but does anyone have any information on the neck joints on Martin bowlbacks?

I have one in for repair which is pulling away at what would be the heel area (if bowlbacks had neck heels!) with the usual "kink" in the fretboard being evident. So this does suggest a dovetail or at least something other than the Neapolitan style construction. BTW I've seen John Hamlett's post about Martin flatbacks, which may be all the information there is, but a guy can hope at least :grin:

Take a look at this article about a broken 1899 Martin bowlback style 5 by Michael Simmons on Fretboard Journal site. Should give you some idea of what the neck joint looks like. What year is the one you are working on?

These two photos especially:

Attachment 202580 Attachment 202581

Oh wow, that's not the joint I was hoping for for sure!

This one is 1919, nice mando, but the neck definitely needs fixing:

Attachment 202583Attachment 202582

Whoops! I am guessing that they changed their neck joints from 1899. I looked in my two-volume Martín book but they don;t Bert that far down to the granular luthiers level. Sorry. Ate worst you could contact Martín directly and see if they still have any historians or people who know the bowlbacks.

I wouldn't be surprised if the neck will pull loose with just a little wiggling and perhaps a gentle tug from your hand once you lift the fingerboard extension.

But if not, the only way you can be sure of what's under there is to either remove the whole fingerboard, or remove the section from the soundhole to the 9th or 10th fret. I'd probably pull the 9th fret, saw through the slot with a razor saw, and lift it from there to the soundhole.

The only Martin mandolin neck joint that I have personally exposed was a dovetail. But that was on a circa 1929 style 20, which was a carved mandolin and a completely animal from the one you are working on. I would not necessarily expect to find a similar joint on your bowlback.

I would guess that it would be a conical block with some sort of dovetail. I know inexpensive American bowlbacks often had neck and conical block as one piece but I highly doubt that Martín would do that.

I looked closer and see that small nail in your photo which would indicate to me separate pieces.

Again I would contact someone in Nazareth who might know. I am not too hopeful but you never know. I think Eugene Braig has a teens Martín bowlback and might have had work done on it by someone. Perhaps another long shot?

this is how Lyon & Healy did it for a mid to low range instrument:

Attachment 202592

Quote:

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Originally Posted by Jim Garber

Again I would contact someone in Nazareth who might know. I am not too hopeful but you never know.

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Thanks Jim: they're repair shop is currently closed until further notice it seems, but I've sent a message in anyway so we'll see.

Otherwise I suspect/hope that rcc56 is correct that once the fretboard is released, it might all fall apart. My worry is that the top extends over the neck in a "sandwich construction" type of thing, but the other examples suggests they might not have done that. 🤞

John, I removed the original fretboard and replaced it with a tapered one on a Martin 00 student model some years back.
Inexplicably, I no longer have the mandolin, for it was very pleasant...nor likely can find photos in the short term.

If my memory serves me well (and it might not) it was a dovetail joint and accessible once the fb was removed, that is, not covered by the top.

Work was very clean throughout the instrument as expected.

An interesting feature on that Martin was a length of thin steel flat stock set into the neck (in the business direction) apparently as some proto stiffening device.

Sure enough, the neck itself wasn't the or the cause of the neck / action issues but a slight bit of overall rotation upward at the entire neck / neckblock / bowl assembly. Neck attachment was muy solid.

Martin reinforced that area of the top north of the soundhole which might have helped prevent this problem from being worse.

I look forward to what you find out from CFM and how the repair proceeds.

Mick

OK, and the result is.... Dovetail:

Attachment 202782

3/4" back from the neck/body join just as predicted by John H.

However, someone has been in there before me, and there's a wedge driven into the normal gap at the rear of the dovetail, I've drilled a hole through to the pocket below it and half steamed it to death but can't shift the thing. Doesn't help that these are next to impossible to hold on to. I did try and rig up a jig to apply constant pressure (similar to the regular guitar neck removal jigs), but it was super-unwieldy with that wobbly bowl.

Ideas anyone? Excavate out the wedge maybe?

Yes, I would take out the wedge, or at least as much of it as you can.
If the neck still won't come loose, you can try a small amount of vinegar [from a syringe] over the joint from the top, not in the pocket. Let it soak a few minutes and see if the neck starts to wiggle in the joint. Repeat if necessary. It will discolor the wood and may damage the finish, so it's a last resort.

The dovetail must have been very well fitted if a wedge on the back didn’t separate the neck and body, so removing it still leaves a tight joint, but one that’s probably easier to loosen. Other than a specialized cutter, a series of drill holes followed by a side-cutting bit for cleanup should do it. It might be quite short, and unglued. I imagine (based on no experience whatsoever) that steaming a joint removes the accumulated brittleness that might help breaking an old joint loose once it’s cooled down, so a repeat steaming might be needed.
Good thing nobody would trust me with this kind of job.

On reflection, I don't need to remove that wedge as such - just enough from the middle of it so that it's no longer exerting "drag".

I might have an idea for a removal jig too, but that will have to wait for next week now. It's usually the way to go though unless you have 6 hands ;)

Richard: it's neither short nor unglued, I had to double check that my drill wasn't going to go right through the instrument when drilling a hole for the steam, but there is a small pocket down there if you go far enough!

Thanks everyone.

I would remove the wedge using a saw that I have very similar to this:
Attachment 202784
after first drilling a hole to start.
If you don't have such a saw and don't want to purchase one for this one simple job, a saber-saw blade and a pair of Vice-grips will work in a pinch.

Thinking about it further, there is no need to completely remove the wedge, just cut a kerf through the entire width so that it no longer prevents the dovetail from loosening.

I recently had a tough time getting a joint apart with steam so I switched to the heat rod. The heat rod did the trick without the worry of steam/moisture going everywhere. You could drill a couple of holes into that wedge and apply the heat rod for a decent period of time. Might help.

Quote:

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Originally Posted by sunburst

Thinking about it further, there is no need to completely remove the wedge, just cut a kerf through the entire width so that it no longer prevents the dovetail from loosening.

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Nod. That's what I was thinking, as long it's no longer a gripping both sides I should get in there.

Update: once that wedge was out (I just drilled a row of small holes and the rest pretty much crumbled away then) a lot of wiggling with the steam sorted things.

As I rather anticipated, shims rammed in at the top of the join and nothing much at the bottom where you need it.

Thanks everyone!

Just to conclude this thread with some more images, first the dovetail:

Attachment 203470Attachment 203471

And yes, that was a cracked neck block which needed fixing.

Then all finished off, if I had my time over I might have shimmed slightly differently, as the bridge ended up about 2-3mm higher than perhaps is normal for these, though it's still all within range. I have to say, I do like these old Martin's, so grossly under-valued for what they are!

Attachment 203472Attachment 203473

And the obligatory sound clip:

https://www.youtube.com/watch?v=hONuJ3rJfJo&t=11s

I got the title wrong BTW, she's from '19 not '16!

John: great work and it sounds so sweet a clear. Bravissimo!

Nice work, as always, John.

I had a hunch you would turn up a dovetail joint, as that is what I've found on my Martin bowls.

Glad you were able to get it sorted out.

The bridge does look a little high, but not as high as the new bridge they're building nearby here over to Canada.


We joked a few years back about the "Eugene Factor" and the subsequent jump in the prices for Martin bowlbacks after he was touting them here.

We might see a "Tavy Factor" next....;)

I've certainly enjoyed playing mine.


Mick

Quote:

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Originally Posted by brunello97

We joked a few years back about the "Eugene Factor" and the subsequent jump in the prices for Martin bowlbacks after he was touting them here.

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Haha, it's a conundrum when you see something being consistently undervalued, do you keep that to yourself and enjoy the fruits, or shout it from the rooftops? :)

OK Since I don't play them myself, here's another one: Stella 12-strings. Often completely and hopelessly broken, a friend of mine picked one up for £50, I honestly didn't think it was worth spending money on, and it wasn't from a strictly financial perspective, but after a neck reset it was just way too much fun to play. Just so much cool mojo it was untrue.

Keep it to yourself obviously ;)

Restored one a couple decades ago for a friend, he tuned it in open C and it sounded like a piano. It was huge, way cool. I think he got around 5K for it. Ry Cooder was looking at it, but I think someone else bought it. There are few 12 string Stella's that have all the parts from the same guitar. With a 26.5" scale length and 12 strings they tend not to last and it may take several guitars sharing parts to make one.

Pre-war Stella 12's in spruce and mahogany are bringing $10K US or more these days if they're in good shape.
The pre-war birch models are bringing several thousand.
Even 1960's models are worth $500 - $800 nowadays.

I'll join this merry band of hijackers.

Here's a 1929 Stella 12 for posteriority. The web FJ article is from 2014 so the $5500 price tag has gone up a long way into the mentioned 10 large range.

It's a beautiful guitar.


Mick

Well I must have been looking at the wrong prices.... I had no idea! :)