You could try a round headed hex key they are designed for use at strange angles. Hex keys are also fairly easy to bend so you might be able to bend one so it will fit. My other thought was maybe its metric(or standard) whichever you aren't using.
The hex keyset I bought comes with both metric and non-metric. The 4mm and the 5/32 inch seemed to be the best candidates.
In the process, have you inadvertently rounded off the female truss rod end by using a hex key a little too small? Does the hex key you are using fit snugly in the truss rod female hole? Is your hex key too long to fit properly in the truss rod hole?
None of these questions are intended as an answer to your dilemma but the answers to them might be of help in determining a course of action.
I don't think it's a problem with the female truss rod end at all.
I think it's the headstock, and how the female truss rod end is fitted and located.
I have just taken some photos that I believe may possibly explain the problem.
The truss rod is in a "compartment" in the wood of the headstock. This "compartment" of wood shields the truss rod from having the Hex key go in and adjust it.
As you can see, a typical hex key cannot be entered into the "compartment" into the female hex opening at a right angle, due to the wood getting in the way of the entrance:
What it looks like when I try to use a hex key:
The hex key cannot be entered in a perpendicular angle into the truss rod..
if you run out of saddle adjustment the proper thing to do is to shim the neck pocket, typically with business card stock. You should be adjusting your truss rod before doing anything else during a setup.
It can be a pain to reverse engineer the truss rod hex key. You put back pressure on the neck while adjusting? Ideally the truss rod should have zero tension on it during adjustment.
The reason I wanted to adjust the truss rod is not when I lowered the action at the bridge, but when I decided to install higher gauge strings.
Naturally the heavier gauge strings generate a bit more bow on the neck, which is easily alleviated by the truss rod. I didn't make that clear enough in the opening topic because I was fixated on the hex-key situation :s
Whether or not strings should be completely loosened while making a truss rod adjustment seems to be up to debate.
Most people I've spoken to adjust the truss rod while the strings are still in tune. I do it that way too. Have not seen it bring any damage to instruments, and it is probably more practical.
Since I first learned that builders have been making ukuleles with truss rods, I've wondered if they truly believe their customers will be using them. Is that really a truss rod in the Vorson, or a hex-head bolt made to look like there's a truss rod? (Sort of kidding) In addition, I've wondered how well they work. Does a truss rod give you the intended adjustment capabilities you want (need??)? If it works as intended, is it sufficiently controllable on such a short neck? Is it "smoke and mirrors"?
I'm not impugning builders and manufacturers. I'm simply skeptical, by nature. Any thoughts?
I've owned several ukuleles, both acoustic and steel-string electric that have perfectly functioning truss rods that do exactly what they were designed to do. Eg: Pono, Risa.
I've also owned short scale guitars and basses that are similar in size to ukulele with perfectly functional truss rods.
Personally I think it makes sense to have a truss rod on tenor, baritone and steel-string ukuleles. It gives you more control over the neck. Higher tension strings, even if they are nylon, can generate enough force to cause the neck to bow forward. Without truss rods, we are left with fewer options (saddle, nut) to compensate for the change in action/playability in the neck. More and more classical guitars also come with truss rods too. Mine has a truss rod, and it has been very handy.
One of the first things I read about truss rods is that often on the low end they do not work or work right so that makes that mostly for show I'd guess.
It depends on what you define as "low end". Inexpensive guitars from well known brands such as Squier, Epiphone, etc - as low-end as they are, their truss rods are all functional. I wouldn't be surprised if a totally no-name brand churning out junk had truss rods that didn't work.
The Vorson is well made for what it is. I would expect that the truss rod was intended to be functional... but we shall see
