Official Luthiers Forum!

more pooh

Generally if you must clamp it that hard there is too much stress on the joint for it to hold long term. You could also split a side or pop any back braces if clamped and glued as is, the stress will find the next weak point. sometimes a graft is the best repair though not the prettiest.

How is the guitar for hydration? Is the seam tight at the blocks?

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Seam is tight at the neck block and right at the heel block opening right after.

By graft are you suggesting a very very very slender piece of maple slid into the crack?

I suspect the guitar has been this way for many years.

What about leave it open and multiple interior diamond cleats?

Yes a graft would be a sliver of wood inserted into the void. Since it is tight at the blocks that would be a last resort. Will need some cleats no matter how you fix it. But I would not cleat it open like it is.

You mentioned hand made, could have been bad joinery or improperly seasoned wood that led to this. Sometimes figuring out the cause gives insight on the best repair.


Will it close up if you simply press down on it? Could have just un- arched a bit. If not my first course of action would be to assess the moisture content of the instrument. Does it show fret sprout or signs of sprout repair?How prevalent is the grain raising on the spruce top? If these or other signs point to a dry guitar then Humidify for a few days and see if the gap moves. Track it with a feeler gauge at marked spots.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

If the crack has been open for years it is full of dirt and who knows what else. You will never get glue to hold on without extensive cleaning and probably even scraping out. Probably will need a spline to get her closed.

more pooh

End grain glue joints are the worst orientation for strength. I would wager that is why the original joint failed. I suggest adding some threaded inserts and make it a bolt on. There is plenty of meat in that heel to install a couple of long inserts so this should be plenty strong. You can't access the bolt head though a non-existent soundhole, but there are ways around this. Usually people make a long allen key and go though the hole in the end block.

BRAVO! Neat axe, too. I'd say from the cat's eye sound holes there might be some Roger Rossmeisl influence. Of course - he was German, and so is the family of Hoyer instrument makers.

_________________
"Act your age, not your shoe size" - Prince

more pooh

Looking at the picture before clean up it appears the only glue joint in that system that held up was the "weak" end grain joint. If the other three surfaces had been properly fitted and glued that neck would still be in place. I wonder if there wasn't a previous neck reset somewhere in that guitars history.
Go ahead and repair the neck block and then take a close look at the side and bottom glue surfaces and add the appropriate shims to make a nice tight fitting joint. That large of a glue area should make for a rock solid neck joint.

All looks like classic drying out.....

At this point you will need to add wood as needed so the joint can be re-fit tightly. I would clean up the headblock to be true and add to the neck shaft as it will be easier to work on than the body.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

more pooh

OK, one more pitch for the bolt-on conversion. The real reason to do this is it would be much more secure than this weird neck joint. There really isn't much there to keep the neck in place if only glue is used. As far as originality being sacrificed, who is going to know. It would be nearly invisible.

Do what you want, but I think you will have to go with this option eventually, when the joint fails again.

more pooh

That's fine. I will bow out of this discussion now.

more pooh

No worries. Have a good holiday.

Not one quite exactly like this but non dovetailed M&T neck joints are not uncommon on old arch tops. It is a continuation of viol family construction and in application is strong enough for the job on an archtop. They are as you note much harder to clamp.... the factories that made them had special jigs to clamp and align the neck at the same time. The only benefit this joint has is that it can be aligned during assembly without any wood working.... I suspect that is why glue contact was a bit sparse on the cheeks of the tennon which led to a weaker joint and when the RH dropped it popped.

Clamping is a pain... The necks are prone to squirming away from desired geometry as you apply pressure to the clamps. Over clamping as you did the back will make it worse. As you get the clamps on it gets hard to run straight edges to confirm that geometry is still correct. Pulling the heel into the body I find a ratchet strap around the body with some spreaders and cauls as needed is the easiest way. Last one I did in my big go bar deck that allows work on completed guitars.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

pooh hole!

Easier to cut and fit? Perhaps. Easier to attach a neck? No.

The dovetail has further advantage. It is self locking. You can assemble and string a guitar with a properly fit dovetail with no glue and it will work just fine until something jars the neck from behind. This feature greatly helps reduce the problem you are having here. How many dovetail neck joints you ever see just pop? Even when dropped or stepped on the neck or body will break before a dovetail joint does. Not the case with a straight M&T which is always popular construction on cheap flat tops, and those guitars you do see neck joints pop apart.

The Germans alway did things different. Zero frets, fender style bolt on acoustic necks, etc.... ask yourself why these things never took over the world? Meanwhile American construction methods like dovetailed necks, X-bracing etc has become industry standard. In the end this type joint was done most likely because it was easier (read cheaper!) to make and this is a factory made guitar. The goal of a factory has always been to make money, as much as possible. Other concerns, even product, are secondary to that. I doubt many actual Luthiers who build archtops use a straight M&T joint.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

pooh!

OK. Next time I will not say anything.......

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Toxophilite, I was slightly interested in this repair. Until you started being a dick to the people commenting. Now I'm not interested at all. Have fun with your guitar and your superior intellect.

Well! Toxic's reaction is certainly childish, flinging pooh around like that. Maybe Santa didn't visit him this year .

He completely left the forum over this... eliminated his profile.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/