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andyonbass

Rounded trussrod hex nut.

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Had to admit defeat on this one, it's in a cavity that is only just big enough for an Allen key to fit (see pics) and I don't have any tools suitable Hopefully not too difficult for a skilled tech with the correct tools 🤨. Does anyone know if repair shops are open during this lockdown and any recommendations where to take it? I travel a bit through work, around the South/south west and Midlands quite a bit generally, try to avoid London wherever possible!! The Bass is a Letts Custom Fretless that I picked up in a trade deal and it's a really nice instrument  but just needs a tweak to the trussrod. Unable to contact Letts. I have looked through the recommended Luthiers thread and have a couple of ideas but thought I would enquire here to see if anyone has any up to date suggestions....

Thanks in anticipation.....

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If it's a 5mm hex, you could try using a T27 Torx on it as it's 5mm point to point.  This worked for me once, the star shape managed to find something to push against and turned the nut

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paging @Andyjr1515 

 

the torx suggestion is a good one too, the traditional solution is to find an imperial hex key that is a smidge bigger and hammer it in.

whatever happens you will need a new nut for the truss rod anyway so slightly damaging the old one won't matter much as long as it comes out.

I'm hoping this is down to user error on the part of a previous owner and not down to the parts themselves as i have a 5 string Letts bass myself, i've never touched the truss rod (It was tweaked 6 months after i got it wen i had it set up and not at all since)

Matt

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1 minute ago, Matt P said:

paging @Andyjr1515 

 

the torx suggestion is a good one too, the traditional solution is to find an imperial hex key that is a smidge bigger and hammer it in.

whatever happens you will need a new nut for the truss rod anyway so slightly damaging the old one won't matter much as long as it comes out.

I'm hoping this is down to user error on the part of a previous owner and not down to the parts themselves as i have a 5 string Letts bass myself, i've never touched the truss rod (It was tweaked 6 months after i got it wen i had it set up and not at all since)

Matt

Putting a very slight taper on the end with a bench grinder first is also a good move.

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As the other posters have stated, the only way that's coming out is to jam something into the nut.

Filing/sanding a slight taper on the flats of a allen key can work.

If you can get enough reach with a Dremel and a 'dentist' bit you could cut a couple of slots in the nut (doesn't have to be tidy) and use a large, flat blade screwdriver.

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I managed to remove a damaged truss rod nut once by filing down the next size up Allen key to a slight taper,  and it wedged itself in 

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The first question to answer is this : single or double action truss rod ?

If it's a double action truss rod, the nut is non removable, so the only solution is to replace the truss rod, which means going to a luthier or politely ask @Andyjr1515.

If it's a single action then the nut can be removed. As the nut is already dead, what I always do is cut the long part of an Allen key then glue it with two components glue in the nut and then remove it using the correct standard key to unscrew the whole assembly.

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1 minute ago, Hellzero said:

The first question to answer is this : single or double action truss rod

That’s true Hz, the one I removed must have been a single 🙂

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5 hours ago, Hellzero said:

The first question to answer is this : single or double action truss rod ?

Forgive my ignorance - how does one tell?

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I like the idea of tapering the next size Allen key, as it needs a 90° bend to fit into the cavity and I don't have any Torx drivers that would fit. I don't have a bench grinder either come to think of it! 

I'm happy enough to seek expert help rather than risk my hamfisted attempts!

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I’m not familiar with Letts, have you spoke with them to ask their advice 🙂

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31 minutes ago, Reggaebass said:

I’m not familiar with Letts, have you spoke with them to ask their advice 🙂

I have tried to contact Jon Letts but the website doesn't work. A search reveals some horror stories regarding customer service and business practices so I haven't pursued further.

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Posted (edited)

Jon Letts hasn't been heard from for a while now, it all got a bit messy and he dropped off the radar about 5 years ago. a bit of a shame really as i quite like my 5 string singlecut and might have commissioned a fretless twin to go with it. 

 

if the nut can be turned then it should be fairly easy to work out if its double or single action, gently unscrew it, if it gets easier to turn then it's probably single, if there is any resistance then it's probably double action, but obviously getting a pro to look at it would be the safest course of action.

Matt

Edited by Matt P
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Hi @andyonbass 

I can't be sure, but that looks like the type of trussrod where the nut is welded to the rod and so can't be removed.  In fact, it looks a bit like this type, where the adjustable nut itself is inside a fixed outer metal cylinder:

SYpavqzl.jpg

The good news is that there are still distinctly visible facets and so an allen key shape, if it was the size of the slightly enlarged hole, will have enough purchase to turn the nut.

While the Torx option is often a good thing to try, I agree - you need something allen key shaped to get into that very restricted space, so I think the filed-down allen key is a decent option (incidentally, if you do have a set of imperial sized allen keys, often they are a few 1/10ths of a mm larger or smaller than the metric ones and sometimes you can hit lucky with one that is just enough bigger...)

You don't need to be super accurate with the faces - you just need it to be small enough to get into the chamber and jam itself against one of the flatter faces when you turn it.  Start with an allen key 0.5mm bigger than the original one.  It takes a bit of patience - the metal is HARD, especially the outer layer - but I use just a fine needle file (the diamond one shown is from Hobbycraft - a set is dirt cheap and they are remarkably good!).  Here's one I've done that way that I use for a similar problem.  This is about 0.1mm bigger than the next 0.5mm smaller key in my set : 

UFzMxGsl.jpg

 

 

 

 

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Thanks @Andyjr1515, I think I'll give it a go with the Allen keys and a file. If I can get it to work, would you suggest I try and undo the nut fully to establish whether it is the welded type as described above or just give it the tweek it needs? I would like to be able to adjust it if necessary in the future without the risk of rounding off the remaining faces although if my file work is successful I might be able to use the key again

Watch this space!!

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21 minutes ago, andyonbass said:

I would like to be able to adjust it if necessary in the future without the risk of rounding off the remaining faces

Tap and Die it,

 

Get the next gauge up hex grub  screw. Cut threads in the rounded out nut. Screw in the new grub screw having coated the threads with a strong epoxy.

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1 hour ago, andyonbass said:

Thanks @Andyjr1515, I think I'll give it a go with the Allen keys and a file. If I can get it to work, would you suggest I try and undo the nut fully to establish whether it is the welded type as described above or just give it the tweek it needs?

I'm pretty sure it's a welded one. 

That said, I would give it 1/4 turn loosening first, just in case it's gummed up, and then tighten back up and carry on to the adjustment you are aiming for.  Then you know it's free and working.  Given that the photo shows a definite flat, you should be able to use the same modified key in the future.

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bit of cooking foil on the end of the allen key can sometimes get enough grip.

Torx keys are also available.

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Posted (edited)
1 hour ago, Andyjr1515 said:

I'm pretty sure it's a welded one. 

That said, I would give it 1/4 turn loosening first, just in case it's gummed up, and then tighten back up and carry on to the adjustment you are aiming for.  Then you know it's free and working.  Given that the photo shows a definite flat, you should be able to use the same modified key in the future.

Prior to the above it might also be worth a squirt of wd 40 as far into the side(s) / back  of the adjuster  nut as you can get.  Allow time to soak in which may help with any 'gumming' up of the threads.

Edited by 3below
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Following on from the helpful advice above, we have a result!! I managed to file an Allen key down and apply a ¼ turn which has given the desired result 😊 

It's the first adjustment needed in over a year of ownership so I reckon I now have plenty of time to refine the tool or find another that will make the job easier next time. 

Thanks for all the helpful responses! 😁😁

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that's excellent!

any chance of a pic of the whole bass? i'm curious as to which shape this one is as Jon seemed to vary the designs from basss to bass.

 

Matt

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Posted (edited)
2 hours ago, Matt P said:

any chance of a pic of the whole bass? i'm curious as to which shape this one is as Jon seemed to vary the designs from basss to bass.

Here you go 

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1671199616_Screenshot2021-04-10at19_35_54.png.7593ffab8fd9bb7961145c564990e6d5.png519421269_Screenshot2021-04-10at19_37_48.png.785bebdb2addcb5a80828afd14eca741.png1676835404_Screenshot2021-04-10at19_37_22.png.39fa16790139f54ba51898ccf804c913.png

Letts custom fretless 5 string Bubinga front and back 34inch scale Walnut neck and body sandwich Padauk out riggers and nut Indian rosewood fretboard Custom double blade passive humbucker Volume/tone series parallel push pull switch Hipshot ultra light tuners

Edited by andyonbass
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That's a beauty! Some of Jon's basses are a bit unusual but thats one great looking instrument. 

 

Matt 

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