Neck heel crack repair on beater mandolin?

[HoGo]

Thanks for the advice, I will look into epoxy (I may actually have some around). The difference is that the people sending rockets to the moon knew what they were doing, while I don't

I would advice against using epoxy unless you disassemble and clean the parts. Epoxy is incredibly strong stuff and had great gap filling property but it's adhesive strength is very poor when used on contaminated surfaces or some incompatible materials. In this case even if you manage to get the epoxy into the crack n good quantity (epoxy is one of the worst in this respect except some very thin varieties) and clamp it, the epoxy will just fill the space between lots of glue and filler. So you'll be basically gluing the failed filler and glue back together and not gluing wood to wood. I've handled enough of these mandolins to be pretty certain the neck was fitted pretty roughly into oversized mortise and secured in place with pins and lots of glue to fill up the space. Any final gaps filled with putty and finished over with the opaque poly lacquer. You may hope yours is better but I wouldn't believe untill you look inside.

[Tavy]

I would also advise against epoxy: it forms a brilliantly strong joint, but a malleable one, which is to say it will move over time, exactly what you don't want here. And once it's in there, it's impossible to get out again.

[mandocello8]

exactly right, difference between luthiery and alligator dentistry made plain. if i had a mandolin like this, "$0 value but i like how it sounds", i would force the neck completely off (causing unknown amount of damage), clean the mess inside all the way to good wood (if there is any), glue it back using marine-weld epoxy, making sure all voids are fully filled. main difficulty would be to keep correct alignment and to prevent epoxy from running out everywhere. i would spend no more than two evenings on this, 1st to get the neck off, 2nd to glue it back. i would probably use a bolt-and-nut and some spacers to hold everything in alignement. after the strings go back, expect two surprises: neck is bent, action is mile high, and A strings do not stay in tune because cheap tuning machines. time wasted, $0 value mandolin ruined? instead, i could have watched many cat videos or learned 1 new tune...

[kdlrd]

Well, nearly a year after asking advice I finally found the time/courage to attempt the repair (I also acquired a better mandolin in the meanwhile). I ended up attempting to drive a 2 1/2 screw through the neck heel, which only halfway worked... I think I drilled the pilot too small as I was expecting a much softer wood. The screw went in but got stuck towards the end (how stuck? I couldn't move it either way with plumber's pliers), so I left it there and added some extra thin CA in the crack for good measure. It does not feel like the neck is moving, so it is probably OK. But now I have a screw sticking out the neck heel, which I have to work around when I play anywhere but in first position.

Anyway, the mandolin is good enough to throw in a carry-on when I travel for work... which ended up being the main reason to keep it.

[ProfChris]

Hacksaw the protruding screw off and tidy up with a file - can't look or feel uglier than a protruding screw head!

And if the screw pulls out over time, drill right through as I suggested and use a nut and bolt.

[Tom Haywood]

I repaired what looks like the the same problem on a similar slightly more expensive mandolin a couple of years ago. I took the back off and discovered that the neck block was rotating under string pressure due to not being glued to the ribs! I think I posted some photos showing the issue. The neck rotated with the block and was firmly seated in the block, so the screw idea would not have worked. The back came off with almost no effort, which was the big clue. It appeared that hide glue was used and it was sponged on insufficiently. There were glue gaps everywhere. The repair was worth way more than the value of the mandolin.

[Rob_O]

This is the thread I was looking for when I signed up for this forum. I bought a beater mandolin cheap and it has the same issue, crack at the heel of the neck and mile high action at the 12th. Unfortunately, no new answers.

I'm going with a trim screw in the heel, maybe countersink the hole a bit so if it works I can cover it with a little wood putty and use a furniture marker to hide the mess I made. If that doesn't fix the action I can still use it to learn some chords.

If nothing else, it will make a nice wall decoration