Yamaha FG260 12-string restoration

[curtisa]

Something a bit out of my comfort zone - an acoustic refurbishment! All those flimsy bits of timber and fragile components is enough to make my teeth curl and toes gnash with fear. Perhaps this will keep @Andyjr1515 and @Norris happy while I flail around aimlessly trying to pull this off

Some years ago I was gifted this old Yamaha FG260 12-string acoustic by my old bass player friend. It was one of those guitars that just hung around various homes, and came and went with people moving in and out of rental properties and student accommodation buildings. Unsurprisingly it's had a hard life, but for the most part it still works as expected - it will tune up and make acousic guitar noises, and nothing appears to be irrepairably missing or broken. Indeed, since coming into my possession it has even been fired in anger and was used for some 12-string texture on a recording or two:

Essentially it is nothing more than Yamaha's re-interpretation of a Martin dreadnaught 12-string guitar with a slightly unusual slotted headstock. For those that are curious, the FG series by Yamaha was first introduced in the late 60s, and included models covering nylon-strung classicals, clones of Martin dreadnaughts, 000's and the like. the 'FG' I believe stood for 'Folk Guitar', perhaps a nod to the burgeoning hippie culture that was just emerging at the time in the States with artists like Joni Mitchell, Jefferson Airplane and numerous other folk-rock outfits with a 'J' in their name.

I'm greatly indebted to Dave who runs the Vintage Yamaha FG webpage for some of the information he's put up regarding this line of instruments. The level of detail he has provided on his site regarding serial numbers and date codes has enabled me to date this particular guitar to run number 379 of 8 Jan 1975. According to his site, the serial number is derived from the number stamped on the brace immediately forward of the soundhole, an 8-digit number formatted in YMMDD<production run number, 3 digits>, in this case '50108379':

The manufacturer's label also reinforces the age of the instrument, as the layout of the text changed throughout Yamaha's history. Here, the tan colour of the label and the orders of the text, 'Republic of China' and 'Made in Taiwan' suggests that it was produced between mid-1974 and mid-1975 (see his website for details):

Other additional production stamps and identifiers are provided within the guitar body, namely on the neck block. According to Dave this is a sequential number and cannot explicitly be used to date it (that's what the datecode on the upper brace is used for):

And the sides ('scuse the dust bunnies - this was a student's beater guitar, afterall):

[Andyjr1515]

Excellent!  I think the fact that it still looks good, and is clearly still playable, is a testament to just how good Yamaha acoustics are

You will find this a very satisfying project

[curtisa]

So what's wrong with this old timer that warrants a thread in ProjectGuitar? Well, as mentioned previously it's had a hard life as a student's throwabout instrument, and the past sins of Yamaha have come back to haunt it after over 40 years. Common internet folklore suggests that Yamaha designed the FG series 12-stringers with fairly diminuative bracing, and the tops are prone to bellying under the tension of 12 of the blighters. Here I've strung the FG with a fairly conservative set of 10-47s, and it's clear that the top isn't really happy with it:

The lateral bellying around the bridge is nearly a full centimetre at the sides in the first picture, and it's pretty clear that the top has collapsed immediately in front of the bridge and pulled upwards around the bridge pins in the second. Some curvature is to be expected in a 'flat top' acoustic, but probably not this much.

Action around the 12th fret is ludicrously high too, sitting at nearly 4mm, another indicator of too much tension over too long a period. Not surprisingly this makes some chords a bit of a challenge to play on anything above the 5th fret or so:

The amount of twist evident on the bridge itself is also clear to see, with almost zero break angle behind the saddle on the rear-pinned strings. Every alternate string on this guitar sounds noticably 'weedier' compared to the opposite pair because of this. The saddle itself is also quite low, having been repeatedly lowered over time to help maintain playability as the top has gradually collapsed further under string tension. I also suspect those bridge pins are non-original, as they don't uniformly site flush against the bridge face (check out the difference between the two unison high-E string pins for example):

:

The string height itself at the bridge isn't too bad, at 9-point-something mm (or about 3/8" of your imperial inches), but the saddle is pretty low with nothing much more to give. You can also tell how much the bridge and top has twisted anticlockwise under string tention when comparing the string angle to the top face:

At some point in the guitar's past the treble-side tuning posts on both of the unison B strings have been broken or lost, and someone has thoughtfully replaced them with some random tuners from two different classical guitars. They do work, but by jove they're ugly compared to the rest. The tuners in general are pretty well shot anyway, being fairly recalcitrant and grind-y to operate:

The neck angle also suggests that tension vs time has not been kind to this instrument, as a straight edge sinks about 3mm below the upper face of the bridge:

[curtisa]

5 minutes ago, Andyjr1515 said:

Excellent!  I think the fact that it still looks good, and is clearly still playable, is a testament to just how good Yamaha acoustics are

You will find this a very satisfying project

Cheers Andy! I'm hoping so, even if only as something a bit different from my usual schtick. As a near-zero value guitar I've really got nothing to lose in getting it playable again, and maybe (heaven forbid) I'll catch the acoustic-builders bug

I should also mention that the FG260, and many others within the Yammy series were all made with laminated tops, but not plywood as such. It has a 3-ply genuine spruce 'tonewood' soundboard . I'm kinda chuffed that it's slightly less crap than your average import-level guff that you can get your hands on these days

[Bizman62]

This one sure is a project I'm going to follow with great interest!

[curtisa]

Thanks Biz. Watch and learn (how not to do it yourself )

[curtisa]

Now that I've got my hitlist of things to fix I can make a start. First thing I'm keen to try correcting is the bellied top around the bridge. Laying a straight edge along the top up to the bridge there's a fair bit of daylight showing between the bridge and the soundhole, indicating that the top has sunk as the bridge has rotated:

The easiest cure for this is a nifty little device called the JLD Bridge Doctor. The idea is that the gadget gets attached underneath the bridge and uses pressure on the tailblock inside the soundbox to force the bridge to twist in a clockwise rotation, causing the sunken area between bridge and soundhole to flatten out and the overly-arched section behind the bridge to sink back down. At the time I worked on this the original Bridge Doctor was on backorder at the usual stockists (or was being charged at some astronomical figue in my local currency), so instead I've cobbled together my own interpretation of it using various bits of scrap and paraphernalia I had lying around in the workshop.

The body of the device I've created from an offcut of an old spruce piano soundboard I had lying around (don't ask, long story), which is then cut up and laminated back together to make it the required thickness. I have no idea what the dimensions of the original BD are like, but if there are any magic forumlas involved to optimise weight or possible tonal influences of the installed device, I'm going to completely disregard them :

The leg that pushes the sunken soundboard upwards gets added as an extension to the body block, again more offcuts from the spruce scrap are used:

A hole is drilled all the way through the block which guides a long dowel and presses it against the tail block inside the guitar. At the opposite end of the block a threaded insert is added which allows a bolt to be screwed in and increase the applied pressure of the dowel against the tail block:

A plastic standoff is added to the body which accepts a screw at the top. This screw passes through the bridge and acts to pull the raised area of the soundboard back down as pressure is increased on the dowel pushing on the tail block:

Finally a bolt and the dowel is added. Cranking the bolt pushes the dowel out the back of the body. With the black plastic spacer attached to the underside of the bridge this then (in theory) translates to a twisting motion that pulls the bellied top down along the axis of the black plastic rod, and simultaneously pushes the sunken top upwards through the axis of the tall piece of spruce at the front of the block. In practice I had to later revise the design several times over to reinforce it, as the amount of tension I needed to twist the top back in to shape was enough to deform some of the components before they'd have enough counter-rotating effect. I won't go into detail here how it needed to be changed, suffice to say that in retrospect I probably should've waited for the original unit to come back in stock and saved myself a lot of heartache:

 

[curtisa]

Marking the location of the screw for the belly reducing doodad is a bit tricky - the middle of the bridge is not the middle of the rear rows of pins due to the paired arrangement on a 12-string, so care needs to be taken in siting this correctly. I also need it far enough away from the bridge pins so as not to interfere with the ball ends of the strings when they're secured, but not so far back that the roundover on the back edge of the bridge means there won't be enough material left to play with when I plug the screw head later on:

Then it's time to bite the bullet and commence destruction. The screw head is counterbored such that it ends up below the surface of the bridge face. I aim to plug this with a matching bit of rosewood to hide the screw:

A quick test fit of the doohickey verifies that it lines up properly and will push and pull things as expected:

And then the dowel and bolt can be fitted. Note again that this is not the final unit I've taken photos of. By the time I had installed and removed it about 5 times to improve its shortcomings I wasn't exactly in the mood to take photos of it.

Quickly restringing the guitar and cranking up the tension on the bolt it's clear to see how much of an improvement the device has made on the top. There's now no longer anywhere near as much daylight showing underneath the straightedge (before and after shots for clarity):

[Bizman62]

1 hour ago, curtisa said:

in retrospect I probably should've waited for the original unit to come back in stock and saved myself a lot of heartache:

Just think about how much you've learned during the process! Not something I'd call a wasted effort.

[curtisa]

Such as, 'if you think you can DIY-it better, think again'? 

[Bizman62]

Rather 'if you think you can DIY-it, do it!'

[Andyjr1515]

A very encouraging result @curtisa

 

[curtisa]

Yes, I was surprised it had that much effect on the top too. It hasn't changed the action much (if anything it's a little worse), but I wasn't really expecting it to do so - lifting the front of the bridge up at the same time as lowering the back of the bridge will largely yield the same height at the saddle. It's more about improving the break angle of the strings behind the saddle on the rear-pegged strings and preventing the collapsed top from getting any worse. Before and after shots of the neck projection below:

[curtisa]

Step two: replace the tuners.

The original tuners on this Yammy are 6-on-a-plate for a slotted peghead. Not dissimilar to classical tuners, just with twice as many per side. The problem is that there is nothing available these days that has the same post spacing that Yamaha used when they built this, so a drop-in replacement is off the cards. The FG used 24mm post spacing.

My only modern alternatives are the Golden Age 6-on-a-plate tuners at Stewmac (23.42mm post spacing - too narrow), WD music tuners (1" spacing - too wide) or the generic Chinese ones available on eBay, Aliexpress and Amazon (25mm spacing). I suspect the WD ones are actually the same as the cheapies, just with a price markup and the spacing is really 25mm rather than the quoted 25.4mm. The other option is to buy 12 individual tuners but the price starts to get silly quickly compared to the value of the guitar, and the added weight of 12 sealed tuners will make the guitar neck heavy.

So annoyingly I'm resigned to plugging the old holes and redrilling for new ones. I've also decided to go with the cheaper option to prevent the cost of the tuners outweighing the value of the instrument. They might be crap, but at least I can get them in a couple of different styles. And if they turn out to be too rubbish in practice they're not expensive to replace.

Here's the old tuners alongside the newer ones, highlighting the cumulative difference between the two post spacings:

The posts on the old tuners are 6mm diameter, but the holes in the peghead have been drilled slightly oversized at 1/4", presummably to give them a little bit of wiggle room for lowest possible friction. The original neck was made from mahogany, but as I don't have any scraps in my collection I'm just using some thing that closely resembles the original timber in terms of colour and grain pattern, in this case some Tas blackwood;

I need 24 of the buggers to do all the holes - that's 12 for the sides where the holes pass through the cheeks of the headstock, and another 12 for each side of the centre portion where the ends of the posts bear against. In reality the only parts that will be visible are inside the headstock slots. The outer edges will be covered by the mounting plate of the tuners:

Then the excess gets carefully pared away until flush. I actually had one plug that dropped straight back out after the glue had cured, hence why the third tuner hole is being reglued in the shots below. The plugs, being such a tight fit with smooth sides tend to push the glue out as soon as you insert them in the holes. Dowels used in joinery tend to have ribbed sides so that the glue has something to hang on to:

All done ready for redrilling. I'm not expecting the existing screw holes to line up on the new tuners, so I'll reassess them once the new tuners are pressed in to see which ones actually need plugging:

[ScottR]

Wow.....my teeth are already curling.

More power to you my friend.

SR

[curtisa]

It'll get worse before it gets better - trust me

[MiKro]

Making a bridge doctor was the right call. The side to side variance is most likely the radius built in to it.  It does look like a lot though? Most I have seen are in the 40ft min to up to 80 ft radius. Very few actual flat tops made in the past century if I am not mistaken? Then again I am old and my brain is fried to a crispy critter at times. LOL.

Looking good,

MK

[curtisa]

Thanks Mike. Yes, I'd expect some arching of the top across the sides, just not this much. Can't blame it really - 45 years of being a lightly-built 12 string under the ownership of many people who might not have cared too much about its health would give me a pot belly too

[curtisa]

Going by anecdotal evidence of other people who had installed a Bridge Doctor I had hoped that the neck projection might have improved due to the counter-rotation the bridge has undergone. Sadly that is not the case in my instance (see photos further up) and the action is still hovering around 4.5mm at the 12th fret. The only other recourses I have at this point to correct this issue is to either lower the bridge by taking height off the top or attempting a neck reset. The saddle is already pretty low in its slot, so I can't really reduce the height of it any further. Lowering the saddle also reduces the break angle of the strings behind it even further making an existing problem even worse. I could shave some height off the top face of the bridge and simultaneously lower the saddle which would maintain the existing string break angle somewhat, but the bridge on this Yamaha is already pretty thin. I've also got the screw head from the top flattening contraption I want to plug later on, and If there's nothing left to plug it with after taking the bridge down I'm stuck with an ugly screw head being visible.

So it's time to learn me a new skill - I'm going to attempt a neck reset.

Told you it was going to get worse.

Initial task is to loosen the fingerboard extension over the body. These usually release with the application of heat, so all I really need to do is warm the area up enough to soften the glue bond without affecting any other part of the guitar. I've quickly whipped up a makeshift heat shield that prevents damage to the surrounding areas using a bit of cardboard wrapped in Alfoil. The last thing I want to do is damage the finish, binding, scratchplate or soundhole rosette while I'm doing this:

Then it's just a matter of getting heat onto the fret board using an old clothes iron and periodically encouraging the fret board to begin to lift every few minutes or so:

An old blunt razor blade with the corners ground off helps gets things started once the glue begins to soften:

And gradually inch forward:

The tiny black bubbles on the surface of the fretboard are just natural resins and oils sweating out of the wood as it gets hot. As they dry they just chip straight off again.

Keep going until I can get nearly all the way to the neck/body join. Managed to put a hairline scratch on the top just below the treble side which is a bit of a bugger, but I'm fully expecting the join between the fretboard extension and top to require some touch-up work when it gets reglued again anyway. I'm not too concerned that it won't polish out again:

[curtisa]

There are a couple of ways to approach the next bit. The choice of method depends on factors like the value of the instrument, the construction of the neck joint, the amount of effort involved and the equipment available. The traditional method is to drill a tiny hole somewhere unobtrusive through the fretboard (say under the fret nearest the neck/body joint) and inject steam into the joint to try and loosen the glue and allow the neck to slide apart from the body. The downside to this is that I'd need to sink some more cash into obtaining the steaming gear to perform the operation, which on a no-value guitar for a one-off job isn't really on the cards. Ideally I'd also need to make or buy a special clamp that would apply pressure from underneath to push the neck upwards as the glue is softened, which makes an already expensive and complicated process well beyond the realms of practicality for this instrument.

The other method which is probably more appropriate for me, my abilities and equipment, and for an instrument like this is to cut the neck off (yikes!) and carry out a bolt-on conversion to reattach it. A bolt-on acoustic neck isn't actually as silly as it sounds, and some manufacturers like Taylor install them on their factory-new guitars. It also has the advantage of being easily reversible if I ever need to do another neck reset on this guitar furtehr down the track. I've seen it described by a couple of people elsewhere as the 'Kung Fu neck reset'

Scoring the edges of the heel will encourage the neck to separate from the body without taking big chips of finish with it:

Some tape is used to help protect the finish on either side of the saw cuts:

And then it's time to clench buttocks and start sawing. There's no turning back at this point. The saw I'm using is a flush-cutting Japanese saw with the thinnest kerf blade I could lay my hands on - less than 0.3mm. The thinner the better, as it means I'm removing as little material as possible from the heel. More material lost from the heel from the saw cut pushes the neck closer to the bridge once the neck gets reattached, potentially upsetting the intonation, so the less impact I leave here the less work I'm creating for myself later on:

The tape helps guide the saw as closely as possible to the heel. Some paraffin wax applied to the blade helps the saw cut smoothly as I get deeper into the block. I need to stop before I get to the fret board, so I take it as close as I dare and create a kerf for the blade to follow on either side of the neck:

At this point I have to stop cutting straight down as I can feel the blade just starting to kiss the truss rod. In conversations with Dave from the Vintage FG Yamaha website he had warned me that the rod ends inside the dovetail joint on these guitars, so at this point I have to switch to an angled cut to take away as much of the remaining material while working around the trussrod:

The only way to get the triangular section of neck wood remaining from the sawing operation is to wiggle the neck and body until it breaks out, and repair the broken remains later on:

At this point the guitar is making all sorts of odd creaking and groaning noises (look away now if you are easily upset):

[curtisa]

One thing I forgot to mention above is that before removing the neck I had to calculate the amount of material I needed to remove from the heel in order to angle the neck backwards and lower the action. There are online calculators for just about anything these days, and using this one I was able to determine that I needed to taper the heel down by 1mm at the bottom in order to get an action of about 2.5mm at the 12th - pretty neat! As it turned the heel cap had been applied with a slight gap where it met the body, and some black filler had been inserted to hide the error against the binding on the body. This black filler was exactly 1mm thick.

[MiKro]

I see you will be going the bolt on way. A good choice based on not having or wanting the equipment to work with the dovetail. When I made acoustics I went to the bolt on direction much easier in my opinion. I tried the dovetail way and it is a very tedious process.

Good luck and stay with it slow for now.

mk

[Bizman62]

Cigar box guitars are so last season...

 

[Bizman62]

After having seen the first 250 or so Rosa String Works videos I'd say you've done your homework well!

[curtisa]

Ta very muchly, Biz. I must admit I've stewed on doing anything with this guitar for a couple of years now.  It's only in the last month or two I've hardened up and decided to jump in and get cracking on it. I've not watched any of Jerry Rosa's videos, but I have followed a number of repair clips by fellow Youtube user 'twoodfrd' which helped inspire me to do this.