High action - is this fixable?

[Johnny60]

Hi folks,

Just wondering if anyone has any ideas about whether this issue can be fixed?

A friend’s mandolin has a fretboard that, when viewed down the neck from the tailpiece end, looks to be higher at the tailpiece and nut, than in the middle. Looks like it dips down a bit. The action’s uncomfortably high. The frets are in good shape, and the bridge has been dialled down as far as it’ll go.

Here are some approximate measurements, in 32nds of an inch and in mm...

Action at 21st fret: 3/32” or 2.5mm
Action at 12th fret: 3/32” or 2.5mm
Action at 5th fret: 2.5/32” or 2mm
Action at 1st fret: 1/32” or 1mm.

So, just wondering - is this an easy fix for an experienced luthier? We have the potential to buy this Mandolin (it’s from a renowned builder and sounds really nice) but it’s a real struggle to play it as it is.

Thanks

John

[sblock]

It depends! You didn't specify what kind of mandolin it is! Bowl-back? Flat-top? A4/F4 or A5/F5? Does it have a truss rod? How many frets to the neck?

If the neck has developed a slight bow, this can often be removed easily with a truss rod, so a lot depends on whether the mandolin has one. This makes a big difference in how easily the mandolin can be set up.

The action at the 12th fret should be (very roughly) something around 2/32" = 1/16". It's currently 3/32", so it's about 1/32" too high. That's not a whole lot high, and so you're in the ball park. It's often possible to fit a bridge with a lower profile, or to sand off some of the current bridge base, if you need too, to get the action where it needs to be.

But you ought to check whether the neck joint is stable and whether the neck might be pulling up, or whether there's a bow or twist in the neck.

My advice: If you have any doubts whatsoever, take it to an experienced luthier BEFORE you buy it and get an opinion on what it will take to make this mandolin playable. Sanding a bridge base or adjusting a truss rod is not very expensive. But resetting a neck is! Yes, these things are all "fixable," but the $$ for the fix can vary a great deal.

[Johnny60]

Thanks for the swift reply, sblock. The mandolin is an F5, and it joins the body at the 14th fret. Nothing loose, no cracks or separation, and all stable.

It does have a truss rod - one with a bolt at the end, rather than an Allen key. I haven’t tried adjusting it.

[Richard500]

Isn’t 1mm at fret 1 really high? I’ve seen mostly around 1/4 of that in setup directions. Then, the “neck relief” is measured And is supposed to be very small. Once that’s taken care of, the bridge height adjusted for the nominal measurements, but as mentioned, for something of quality, see a luthier.

[J.Albert]

1. Check the neck relief. Fret the 4th pair of strings at fret 1 and fret 12, then note how much "free space" is at fret 7. Shouldn't be much more than you can slip a piece of paper through.

2. Check the bridge. Is there room beneath the thumbscrews to lower it?

If the action isn't right, or isn't easily "fixable", I'd look elsewhere.

[pops1]

I would adjust the truss rod and see where you are then. While it is not an action adjustment, it has a huge effect on action when it is loose and the neck is bowed.

[thistle3585]

If you dont own it yet then I wouldnt be making an adjustment to the truss rod. I would express my concerns to the seller, ask to either take it to a luthier for an inspection or ask for an approval period with a full refund. Regardless, get it in the hands of someone that can answer your question. You can also contact the builder and get his thoughts.

[ProfChris]

I am, I suppose, a bit of a luthier (though not a good one!). From your description, the work it needs (and in this order, though you could swap 1 and 2) is:

1. Adjust the truss rod as explained by pops1. If it won't adjust, I wouldn't buy the mandolin. Even if the relief is only a fraction too high at the moment, a non-working truss rod will be problematic down the line if the neck moves any more.

2. Lower the nut slots to produce the correct action at the first fret. I'd like it so that if you press a string pair down between frets 2 and 3, the string pair only just clears fret 1.

3. Reduce the height of the bridge to produce your desired action at the 12th fret, which I think would be 1.5-2mm. If the bridge height can't be reduced, then you're looking at a neck reset (which is a skilled job, so I personally wouldn't attempt it on anything but a cheap instrument). That either says don't buy it, or factor the neck reset cost into the price. It would help to know the kind of neck joint the builder used, as that affects how hard a reset is.

So all your issues are probably fixable (if a neck reset is possible), but each has different costs. Relief adjustment is a few minutes work. Nut adjustment is fiddly but not a huge lot more work, maybe an hour or even less. Bridge height reduction is a bit more work, because of refitting the bridge to the top, if it's possible, and bear in mind that you'll want scope for further reduction if the instrument continues to change shape. If a neck reset is needed, that's not cheap!

[Johnny60]

Thanks for all the replies everyone. Very helpful.

[pops1]

If you need to lower the bridge don't do it by refitting it to the top unless it needs it, take wood off where the posts go into the bridge.

[Johnny60]

Thanks pops1. I’m not going to do any work on it, but it’s going to a luthier for a closer look.