How to find the dovetail cavity?

[Jonas]

Hi y'all,

This is not really mando related, but it involves an arch-top guitar. Bear with me.

I need to do a neck reset on a Swedish made Levin arch-top guitar made in 1945. It's a beautiful guitar, but it's not very expensive, so therefore I plan on doing this myself. It will become my Dave Rawlings-style guitar (as if i ever would be able to sound like him!).

Anyway, I'm having trouble finding the cavity in which to put steam. I have removed the 15th fret and drilled around a bit in the fret 'crack' trying to find it, but no luck as it seems. Do any of you have any nice tricks how to find this cavity, or any oter input to help a fellow mandopicker on the way? I am trying to locate the cavity using and old string in the drilled hole.

Thanks!
/Jonas

[Jonas]

This is a picture showing a neck job on a similar guitar, for you to see how the neck joint is constructed. (This is not my guitar and not my photo even.)

[sunburst]

It looks like a pretty shallow dovetail in the picture, but there's no guarantee that yours is the same.
The drill-through-the-15th-fret-slot trick is a Martin trick, for the most part, because is just turned out that the end of the dovetail lined up close to the 15th fret on Martin flat tops, though it works for Gibson flat tops from many years (not all!) and other guitars too. The dovetail in the picture doesn't look like it would line up with the 15th fret slot, so if yours is the same, the 15th fret thing might not work. Also, you have the extender to deal with. On a Martin flat top, once you're through the fingerboard you can "swing" the drill bit around looking for the dovetail pocket because you've only got a small amount of ebony fingerboard to sort of pivot the bit in. Having drilled all the way through the extender, that wouldn't be easy to do.

It looks like you might be able to drill a small hole, on the "passenger side" of the guitar, right at the corner of the fingerboard extender, keeping the drill bit in the extender rather than the top, apply steam, re-set the neck, then patch and touch up the little hole.
In the picture, it also looks like the end of the dovetail might have been glued. If yours is like that, it might not be easy to get loose.

[Jonas]

Great! Thanks John, you're too kind.

I've heard of one guy who went in from the heel, taking of the plastic heel-cover and puttin hot water from that end. Maybe I'll try that. But, I don't understand how to get pressure from beneath to make the neck come loose if the steamer is inserted where the pressure should be put...

[sunburst]

There are lots of old Martin necks with that diagonal hole under the heel cap. That was a common method at one time. Al least it is better than cutting off the fingerboard extension!
Steam, though it quickly turns to hot water, is better to inject into the hole, wherever it ends up.

[Jonas]

Yep, definately gonna use steam. I even bought a used espresso machine on ebay for this purpose!

[BlueMountain]

Remember that it's not the pressure of the steam but the heat of the steam. You'll have hot water coming out of the tip for quite a while before the tube heats up enough so that the steam is actually coming out. The steam will turn to hot water, yes, but no sense in putting in hot water. Wait patiently for the steam before inserting the needle. And remember that the steam is hot, so the tube and needle will be hot, too. A few towels are very useful, both for holding the tube and for mopping up the mess. And it can take longer than you expect to heat up that joint hot enough for the glue to melt.