Difficult to access truss rod nut - headstock end

[Tristan____C]

My partscaster build features a cheap, no-name neck from a well-known online auction site. I've a few buzzing issues, so trying to get the neck straight before identifying which frets are the cause. Here lies the problem.

Access to the nut is annoyingly difficult. I assume the nut is 4mm (a 3.5mm allen is too loose, 4.5mm doesn't go in). All the 4mm allen keys I have won't quite engage. I've attached a diagram of the issue and what I think is a solution.



The short side of an allen key won't engage as it clashes with the bottom of the access hole. The long side of an allen key (with the 'ball end') I'm struggling to get to engage - perhaps I've damaged the nut in all my attempts... Photos attached.

My idea was to use a dremel to file away the bottom 'lip' of the access channel to allow a closer-to-90deg approach to the nut.

Or get a allen key set with a very short short side...

Anyone see any issues with filing away some material?

Thanks,

Tristan

 

[Peegoo]

@Tristan____C

Get yourself a set of metric ball-end hex wrweches. They work perfectly for this stuff.

 

[philosofriend]

The only problem will be matching the color of the dark stain.

Sounds like you are worried about the nut being messed up. Once you get a straight shot with an allen key, the least risky way to proceed is to find a normal (not "ball end") wrench that fits tightly. If the metal in the nut is indeed scarred up, one approach is to grind just the last millimeter of the key to a slight bevel and see if you can force that into the nut. Lube the wrench and don't try to turn the nut unless the wrench is all the way in the nut.

If the nut gets the hex stripped, you have to learn about a barbaric tool called a "screw extracter".

 

[BryMelvin]

@Tristan____C

Get yourself a set of metric ball-end hex wrweches. They work perfectly for this stuff.

^^^^^^^^This is by far the best solution.

 

[Tristan____C]

Thanks all

@Tristan____C

Get yourself a set of metric ball-end hex wrweches. They work perfectly for this stuff.

^^^^^^^^This is by far the best solution.

I’ve many metric sets… And even been trying ones that came with IKEA furniture etc in case it was a tolerance issue on the nut.

It’s the angle - the material won’t let any of the ‘standard’ long side:short side ratio allen keys engage as the lip is in the way. The ball-end keys (typically the longer side) also have that problem but I thought their working angle was up to 20deg. So maybe that’s where the damage may be the issue.

I’ll see if I can get a short allen key set (where the long:short ratio is way higher than usual) or see if I can take a dremel to a cheap IKEA key to cut it down.

Tristan

 

[dsutton24]

Be very careful with ball end wrenches. Make sure you have the driving end firmly seated in the broach of the trussrod nut, the broach isn't very deep, the part of the ball that is actually hex shaped is a way up from the end of the wrench, and it's easy to deform the nut by misusing tools.

Trying hard to explain this without saying broach seventeen times. Broach, broach, broach...

The other problem is that it's easy to twist the ball off, potentially wedging it in the nut. It's unlikely, it doesn't usually take a lot of torque to turn a trussrod nut.

I know that Stew Mac sells the things, and I wish they talked about where and when they are suitable. I think that many times what Stew Mac says is taken as Gospel by folks who don't know a lot about tools and practices. Ball ends are fine when used properly, they shouldn't be the first tool you reach for. Many times an Allen wrench that's long enough to extend beyond the end of the headstock is a better solution if it allows a straight shot at the nut.

Broach.

 

[BryMelvin]

Be very careful with ball end wrenches. Make sure you have the driving end firmly seated in the broach of the trussrod nut, the broach isn't very deep, the part of the ball that is actually hex shaped is a way up from the end of the wrench, and it's easy to deform the nut by misusing tools.

Trying hard to explain this without saying broach seventeen times. Broach, broach, broach...

The other problem is that it's easy to twist the ball off, potentially wedging it in the nut. It's unlikely, it doesn't usually take a lot of torque to turn a trussrod nut.

I know that Stew Mac sells the things, and I wish they talked about where and when they are suitable. I think that many times what Stew Mac says is taken as Gospel by folks who don't know a lot about tools and practices. Ball ends are fine when used properly, they shouldn't be the first tool you reach for. Many times an Allen wrench that's long enough to extend beyond the end of the headstock is a better solution if it allows a straight shot at the nut.

Broach.

I would not use a ball end allen aimed at guitar use (stewmac). If you use a ball end get craftsman, dewalt as a minimum quality. Maybe from a Snap on set. You will regret cheaply made tools. The tools I use on a guitar are essentially the same I would use on an aircraft, or my car engine. More than likely the allen nut is damaged. There are special allen keys for damaged screws (

K Tool International 75422 )​

. Low torque items like guitar parts can sometimes be removed with a Torx which has a taper to it.

 

[Nicko_Lps]

Or get a allen key set with a very short short side...

Or just buy a normal one and cut it down, its very easy to do since you already have a dremel tool.

Measure how deep is your allen head in the trussrod and leave only that away from the allen key corner. You should be fine with 0 modifications.

Ball allen wrench will work as well but it applies more stress and wear to the allen head which can be disaster over time.

 

[NewTimerJH]

@Tristan____C

Get yourself a set of metric ball-end hex wrweches. They work perfectly for this stuff.

This is the solution

Edit: I assume you could just bolt cut or dremel off the end of your 4mm wrench and use pliers to engage it as a quick fix

 

[Peegoo]

If you modify a wrench by cutting it, keep it really cool by frequently dipping it in water because you will soften the steel if it gets hot enough to permanently discolor it (usually blue or black).

A bolt cutter will work on an Ikea wrench, but not on a name-brand-tool wrench because the steel is as hard as the jaws on the bolt cutter. You'll ruin your bolt cutter.

If you have a bench grinder, you can grind a groove all the way around the wrench and then snap it off in a vise. Grind the snapped end flat and you're good to go. Keep it cool!

 

[eallen]

Quality ball end metric, most head adjust were never meant for straight hex wrenches.

 

[Slick_Rick]

I'd file the hole a little bigger personally.

 

[trev333]

Do what your pic suggests.... work that bottom edge down some with a round file of something similar....

many necks have more of a hollow down on the neck face...

 

[Boreas]

Drill baby drill! Or file... If you can't get a straight shot onto that head, it is doomed to early failure. The LAST thing you want is a split/stripped/ruined nut.

The result may look like crap, but use that knowledge in your next decision to purchase a cheap neck.

 

[Freeman Keller]

Access to the nut is annoyingly difficult. I assume the nut is 4mm (a 3.5mm allen is too loose, 4.5mm doesn't go in).

My shop notes say that some Fenders use a 1/8 inch SAE (Imperial) allen wrench for the truss rod adjuster. Fender seems to agree

1/8" Hex (Allen) Truss Rod Adjustment Wrench

Exactly the right tools to use for truss rod adjustments on your Fender guitar or bass.Set of twelve 1/8" Allen wrenches for use with American Deluxe, American Standard, American Special and Highway One™ series guitars, and guitars and basses with a "bullet"-style truss rod nut.

www.fender.com

 

[Tristan____C]

My shop notes say that some Fenders use a 1/8 inch SAE (Imperial) allen wrench for the truss rod adjuster. Fender seems to agree

1/8" Hex (Allen) Truss Rod Adjustment Wrench

Exactly the right tools to use for truss rod adjustments on your Fender guitar or bass.Set of twelve 1/8" Allen wrenches for use with American Deluxe, American Standard, American Special and Highway One™ series guitars, and guitars and basses with a "bullet"-style truss rod nut.

www.fender.com

Yeah - my US std strat has a smaller size. But this is definitely larger.

Do what your pic suggests.... work that bottom edge down some with a round file of something similar....

many necks have more of a hollow down on the neck face...

Drill baby drill! Or file... If you can't get a straight shot onto that head, it is doomed to early failure. The LAST thing you want is a split/stripped/ruined nut.

The result may look like crap, but use that knowledge in your next decision to purchase a cheap neck.

I hear you…. I think the filing option is likely best. I tried a ‘shorter’ allen key, but that didn’t help - it clashed with the upper wooden lip before engaging the nut. A key ‘inbetween’ sizes wouldn’t make it round the corner, so to speak, to be square on the nut. I think a small bit of filing will be simpler.

And yes, this is what I get for buying a cheap neck. The whole reason I’m doing this is to get the neck level to better identify which frets are high, and hoping a tap or two with a fret hammer will get them seated again. If not, I’ll be spot filing. Where I am, it’s just not cost effective to take it to a luthier - and for the cost of a few tools and a few hours or my time I may learn to do things myself. I was planning to upgrade the nut to a Tusq too.

 

[Boreas]

If you have a Dremel you may be able to use a sanding drum slightly smaller than the radius. But even with filing - several layers of masking tape and cardboard would be your friends.

 

[Freeman Keller]

This is how I drill the access hole in the first place, The bit still wants to wander but if you are careful you could releave that area in the first post. The long bit is called an "aircraft bit" (don't know why) and is available at a hardware store

 

[netgear69]

A scalpel with a new blade on will sort that cut very fine slices until you get access dye it up with some amber
going at that nut from an angle will chew it up

 

[Tristan____C]

Well that was simple. I used a small Dremel sanding band, that was just smaller than the access hole, and did a couple of passes at slow speed. That was enough to sort the problem.


I then tried to tidy it up and the band slipped causing that minor blemish to the bottom right of the hole...

I then used the sanding band without the dremel to tidy it up a little better. Apart from the blemish, it would have been a roaring success.

If I want to be a perfectionist I'll need to get a single drop of amber stain! But it's good enough for my needs as is.

Thanks for all the help.