One for luthiers/repairers: hex key ball end stuck in truss rod (how to remove...)

[murrmac123]

Originally Posted by fazool

Drill a small hole in the broken piece using a flexible Dremel extension.

Screw into that hole with a coarse thread sheet metal screw


Grab that screw like a handle and pull it out

It's a 4mm wide fragment of hardened steel ... no way is anybody going to be able to drill a centered hole into that .... all that would happen is that you end up with a slew of broken drills.

Charles has got it right IMO.

[charles Tauber]

Originally Posted by murrmac123

It's a 4mm wide fragment of hardened steel ... no way is anybody going to be able to drill a centered hole into that ...

Agreed, particularly not with the lack of accessibility to it.


Another possible option is to forget about the truss rod and adjust the neck using compression fretting. Less expensive and less invasive than removing the fingerboard and replacing the truss rod.

[Frank Ford]

Actually, you might well be able to drill into that hardened piece if you use a 4mm two-flute split-point carbide drill. It should center within the flats of the hole, and it will drill into the broken piece, but it takes a pretty good bit of pressure to be effective, so you'd probably want to silver-braze the carbide drill onto a fairly flexible, say 18 - 24 inch long rod so you could get a reasonably straight shot into the hole as you go at it with a regular drill motor.

Taking the neck off (if it's a bolt-on) could make the job much easier

The only drill I'd trust for this would be #8842A47 from McMaster-Carr

[murrmac123]

Originally Posted by Frank Ford

Actually, you might well be able to drill into that hardened piece if you use a 4mm two-flute split-point carbide drill. It should center within the flats of the hole, and it will drill into the broken piece, but it takes a pretty good bit of pressure to be effective, so you'd probably want to silver-braze the carbide drill onto a fairly flexible, say 18 - 24 inch long rod so you could get a reasonably straight shot into the hole as you go at it with a regular drill motor.

Taking the neck off (if it's a bolt-on) could make the job much easier

The only drill I'd trust for this would be #8842A47 from McMaster-Carr

Maybe that would be possible Frank, but I would bet the farm that there would not be enough material left afterwards on the flats of the hex socket to facilitate subsequent adjustment with a fresh Allen key.

OP has already said that it is not a bolt-on neck.

[stormin1155]

It's an unbound neck, which will make it easier to remove and reattach the fingerboard. The task of removing the fingerboard, repairing or replacing the truss rod, and reattaching the fingerboard really isn't that difficult. The hard part is making it look like it never happened. That is what is usually most time-consuming, and where a lot of the expense is. Binding makes it harder, because you have to be careful not to melt it when removing it, and refinishing it is more difficult than just wood.

I don't have a lot of optimism about being able to drill it out or dislodge it, just because of where it is. Really no way to get in there with hands and tools, or to see what you're doing. So I wouldn't go out and buy expensive specialty tools to try it.

[Frank Ford]

Originally Posted by murrmac123

Maybe that would be possible Frank, but I would bet the farm that there would not be enough material left afterwards on the flats of the hex socket to facilitate subsequent adjustment with a fresh Allen key.

Risky, yes, but if you have ever done this kind of thing with that specific drill, you might have a different opinion of the chances of success. The two flute drill won't tend to wander or bend the way a twist drill will, and being carbide, it's incredibly stiff. Still would require some creativity to drive it in there, for sure.

[phavriluk]

I think (and 'think' is certainly the word) that trying to drill out the end of a very hard and very small tip of a tool, working blind in a very confined space is no task for someone who doesn't do that kind of precise work all day long.

My suggestion is that OP take this instrument to a luthier and ask what options are available. I think that we responders haven't come up with all of the possibilities yet and maybe one of the ones we haven't come up with is the one that will work. Problem being, it all may be for naught if removing the broken tool end also damages the fitting the tool was meant to engage and turn, and the repair person might as well have gone straight to removing the fingerboard and replacing the truss rod with one of known quality. And someone's mentioned that the truss rod may have been inoperable (corroded, rusted?) and that the tool broke trying to apply more force than it reasonably should have been expected to handle.

Maybe a skilled person could remove the fingerboard, do what needs to be done with or about the truss rod, and reattach the fingerboard without removing the neck, on a good day. Finish damage might be confined to the neck/fingerboard joints. Maybe?

But I am a lay person, not a luthier.

[Trevor Gore]

Do you really need to get the broken piece out?

I've just checked the length of where the neck is on a 4mm ball-end Allen key and the depth of a number of 4mm sockets in grub screws and truss rod nuts. The break will be at the neck in the key, and, if you're lucky, that could be 2-3mm inside the socket. A square-ended key may still engage and indeed, from your photographs looks like it might. That might get you out of the immediate bind if you don't adjust the truss rod too frequently.

If you want to try the freezer trick (not sure it will work, but harmless to try) try finding a good electronic freezer spray. The brand I have is Servisol. Some of these are ether-based. This one isn't, it's mainly tetrafluoroethane, which should get the temp down to around -25C. It comes with a small diameter tube (think WD40) for accurate spraying, but I don't know how you'd cool the broken end and not the truss rod nut as well. But you may get enough relative motion to free it up.

Another method would be to try tapping the ball end into the nut if you can find a suitable drift (a square ended 4mm Allen key) and enough room to swing a hammer. The flats on the end of the ball end may "square-up" as the ball bottoms out in the socket, this slight rotation being enough to free it up.

The bigger question is why did the Allen key break in the first place? If the truss rod is U/S because the nut is seized, at some stage it will need replacing anyway.

[nobo]

Thanks for all the replies so far. Really helpful to have multiple view points on this. Tricky one, isn't it?!?

It looks like this is going to be beyond my capabilities - potentially those of local luthiers/repairers too, not least given the tooling required. But I'll look into it.

I should say, for the avoidance of doubt, that it's not any of the instruments in my signature. It was, I think, an experimental and probably relatively early build for someone (who I won't name).

Having the adjustment end of truss rod inside the guitar in a relatively inaccessible place doesn't seem to be uncommon (I don't think I have a single acoustic which adjusts at the neck end, save for my VAOM-06). However, it being recessed to the extent it is here clearly isn't ideal. At least (unlike with Lowden) there's a hole in the brace so there's a straight line to it.

I'll check, but it seems the neck relief is probably tolerable, so it might be a case of just hoping that it's fine and never needs adjusting (rather wishful thinking, perhaps...!). Or leaving it until that day! Fortunately the climate/environment here is relatively stable, so it's rare that the truss rods on my other instruments need any attention (indeed, I don't think they've warranted it unless changing string gauges).

Still, it'd be comforting to have this sorted... My guess is, given the small size of the guitar, the positioning of the truss rod, and the size of the soundhole, drilling inside the instrument with any accuracy is going to be very difficult, even with a flexible drill bit extension.

I, like some here, have concerns as to the state of the truss rod given how stiff it must have been for the ball end to shear off when altering the relief on the neck. So it may be that even if the ball end is removed, there's still an issue there.

The fretboard is bound (admittedly it's hard to tell from the pics), and fan fretted at that. On the plus side, it's bound in wood (what looks to be ebony with what looks to be a dyed wood (I'm guessing maple) purfling line).

I've no idea what kinda of cost or work would be involved in removing the fretboard (and possibly also the truss road). If that means the whole fretboard needs replacing, I'm guessing that we're looking at, in London, close to, or potentially more than, 50% of what I paid for it... which'd be rather galling to say the least!

[Bob Womack]

Betcha won't be using a ball-end again! But who'da thunk it would break off?

Bob

[Otterhound]

If there is some of the hex portion still available , it may be possible to use a socket to capture it and use this method for future adjustments . No need to remove .
Should the available portion be part of the taper at the rear of the ball end , it may be possible to capture that with a socket that slides over and is part filled with a good epoxy . After this hardens , you may be able to not only turn the ball end in order to ungall it , but also be able to remove it afterwards . 2 birds and 1 stone . Of course great care will be needed to prevent bonding to the wrong things .
Good luck and let us know how it turns out .

[mirwa]

I would use my slide hammer trick, I use this for removing broken truss rods out of warwicks and so forth.

I use a spot weld gun, it fuses a copper pin to whatever steel you contact it with, then you attach a slide hammer onto the pin and pull the offending truss rod or in this case allen key head out.

Steve

[Ned Milburn]

I'm with Charles on this, too. Just take the f.board off and replace the truss rod. Reiterating... For the ball end of a "universal joint" allen key to have broken off, either the allen key sucked, or it was SUPER torqued. Meaning the truss rod may be fried.

The challenge of removing the ball end is quite profound. A few good strong knocks of a hammer with a punch might help dislodge the stuck allen key head, but how in the world will you (or anyone) get some strong knocks with a hammer into that space...?? Baby monkeys, maybe...??

What type of guitar?? Is it worth the effort to remove f.board and replace truss?? Is this something you want to try yourself?? Is it worth the cost to pay someone to do it for you?? F.board removal and truss replacement will NOT be a cheap job. Not brutally expensive, but not cheap. I've done it a few times with excellent results, but I have been honing my crafting skills for 35+ years.