Gibson F9 neck reset and total overhaul

[HoGo]

Hello folks,
I just finished repairs on this mandolin and managed to take few pics along the way for those who are interested in what you can find in low end Gibson. Actually that was the only reason I took this and it took me almost year till I finally took the courage to do the work.
So here is the patient: Gibson F-9 (i don't have the serial, but likely pre-flood around 2010) unplayable as the neck joint is slightly loose and action rises to 1/4" at 12th when strings are tuned up to pitch.






You probably noticed the centerline drawn on fingerboard, when I got it to my hands I found out there is something wrong with symmetry. The top was carved very off-center. The apex of arch and both f holes were shifted more than 1/4" to the treble side. which resulted in wide shallow recurve on bass side and very narrow one on the treble side. You can see how offcener the notches in the bridge are to compensate also the bridge was not centered between f holes the asymmetry was too large.

More to follow.

[HoGo]

After I measured thicknesses of top and back and looked inside I suggested this mandolin could use something more than just neck reset. The top thickness varied randomly from 5mm at edges to 6+mm near treble side of top. I measured 3.2mm near scroll and in few other locations.
The back was all over the map as well, very thick at the edges 3.8-4mm and varied wildly but quite thin near the neck block 3.2mm in few places - that's the area that is typically thickest on Loars.
We decided to open the back an regraduate closer to normal and refinish with varnish/French polish.
I removed the fingerboard, steamed out the neck and removed the back. The inside of the mandolin was not even sanded smooth it was like it left the CNC and there were ugly steps at the scroll block both on top and back whre they didn't carve all the way to the block.


The back was inside carved with some asymmetry and the kerfing was not glued to back on bass side, there was a 1/32" gap carved underneath.
The edges of f holes were roughly cut at an angle inside so the top didn't look as thick on finished mandolin.

The gauze was glued with huge layer of glue and the cloth was not even penetrated fully by the glue.
The upper end of bass side tone bar was sitting on the ramp of the CNC cut and I could insert my fingernail underneath. There were pinholes going right into the top wood at the ends of the bars, perhaps that's how they were held during gluing.

[HoGo]

Luckily, the back edges were between 1/4" and 5/16" thick so I could remove substantial amount of wood from bottom of the plate to get good paltform around edges and carve smooth recurve on the outside and good graduation transition from kerfing on the inside.
I removed the tonebars and glue/cloth reinforcements (the glue was so thick I had to plane it away with my thumbplane) and re-did both outside arch and graduations of top as well enough wood was in the top so I could move the asymmetry of arching bit closer to centerline. I fitted new tonebars and glued them with HHG. I also reshaped the f holes one was slightly narrower and they were quite rough - I managed to remove a bit of asymmetry with this as well.

[HoGo]

And now to the reason why the neck joint failed... There was nice thick layer of putty in the neck joint and a thick layer of glue on the dovetail. Perhaps the mandolin was left in heat but the only joints affected were those within the leverage of neck.

[bernabe]

A little off topic, but whats that jig against the wall. I think I see some F5 side shapes within it..maybe?

[HoGo]

I assembled the mandolin back with HHG, re-fit the neck and angled it for good bridge height and a bit towards the asymmetry so the bridge won't have to be moved so far to side, refretted with thin SS wire, hand stained and finished with oil base and French polish finish. There were some glue stains around the top binding and few tear-outs filled with putty under the thick original finish that I couldn't fully hide with stain on bare wood but it turned out quite good at the end with some targeted touch up.
(I found out the easiest way to remove the finish was to plane it away with thumbplane. I measured the finish shavings and they were 0.15-0.2mm thick on the top and back and twice as thick around neck joint).
The wood was now showing much more figure than before.



Even more to follow later....

[HoGo]

A little off topic, but whats that jig against the wall. I think I see some F5 side shapes within it..maybe?

That's my F style mould (four piece, can be disasembled with the mandolin inside). I think I posted pics few years ago here on MC.

[multidon]

Adrian, I would like to thank you for a very informative an eye opening series of posts. At one point I considered purchasing an F9 that displayed that same line between the back button and the neck. I was told by the store I was not a problem, but for me it was a red flag. I believed at the time it was the beginnings of a failing neck joint so I did not purchase it. Your post confirms that my suspicions were right. After seeing all of these details of construction that you reveal I would be wary of purchasing any F9. If the left that one out the door, how many more similarly flawed instruments are out there?

[dhergert]

I'm admittedly prejudiced because I own an early F9 and respect its tone and volume, however it is out-of-the factory rustic in a number of ways. That said, I think the proof is in the pudding regarding pre-judging a loose neck joint just by the back button. What we really should be looking at is bridge adjustment, and after that, all of the joint area around the neck joint, including around the fingerboard as was clearly shown in Adrian's pictures.

And as Adrian mentioned, this could have been heat damage. Given the widespread joint failures that are showing in the pictures, I'd believe that is what happened.

That said, heat damage didn't cause the carving asymmetry and it didn't cause the excess dope and glue in the joint areas and it didn't cause excess top thickness or the lack of what we would consider normal finish work inside the mandolin.

I can't accurately judge asymmetry or excess thickness by looking inside a mandolin with a mirror, but I can say with confidence that the CNC ridges don't exist on my 2002 F9 and also that it has been smooth-finish sanded. And I can see that the tone bars are fitted and attached properly and that the curfing is properly attached to the top, sides and back. Lastly, there is no glue/cloth around the F-holes.

Looking at these differences, I tend to think something happened in the Gibson shop sometime between 2002 and later when the OP mandolin was built, and it probably also affected other products that came from the shop. We all know what happened, and it is something we're all still sad about.

[Jeff Mando]

The wood really came to life with that finish. Beautiful work, Adrian!

[Jeff Hildreth]

"out-of-the factory rustic "

Classic !

I did not buy a 9 series back when they were introduced as the price reflected the quality, or lack of same.

HoGo's posts and photos have confirmed my early observations.

I am anxious to see, and hear, the final results.


Thanks HoGo... I would like to see more of your work.

[Jim Hilburn]

What's interesting to me is that the close up of the top scroll where you can actually see the binding, it looks like one of the more accurate scroll binding jobs you see from Gibson except you can't see it since it's black in the sunburst. Then you see a Master Model and it will have a hawks-bill look. Wierd.

[Hendrik Ahrend]

Great job, Adrian, thanks for sharing.
One finds this asymmetry not only on low end Gibsons. Here's a 2005 Distressed Master Model:

I made my bridge so that it compensates the asymmetry a bit.

This 2000 Master Model proto is even more weird. Here the asymmetry is to the other side. And the treble f-hole is slanted inwards. Again, a different bridge top makes up for it a bit. Note how the body shape is way different from the DMM's. At least the eagle beak is a little less prominent.

[HoGo]

I'd add that central part of back (visible through f holes) was sanded smooth, though not right to the edges. Other thing is that I suspect the neck joint failure was NOT due to heat. In such cases the joint moves under tension AND sets in shifted position when it cools down. In this case the neck joint was loose i.e. under tension the neck shifted forward and after few weeks without strings (the mandolin spent better part of a year in my shop before I started the work) the neck angle was back to normal.
Here's the follow up...
I assembled the mandolin in the white for some final tuning before finish goes on and found out that bridge is crooked (see picture) and tuners are really hard to turn.
The bridge was milled very asymetrical and I moved the hole in the saddle a bit to compensate, but the hole in the base was off as well. I filled the space between the bridge feet with ebony strip to make it full contact and prevent digging of the inside edges into the top (there were marks in the top when I got the mandolin) also made sure to fit it pre-sprung so the ends won't lift up under tension like it originally did.

After closer inspection I found that all the plastic washers/bearing strips were crumbling from under the wheels. I didn't suspect the holes being driled wrong (CNC machined - checked later with tuners inserted from the face of the headstock - see pic) and found out the tuner posts went through headstock at weird angle, especialy on bass side. I removed the bass side tuners and it was the mounting screws that were drilled quite imprecisely and at an angle (like when you drill it with handdrill without leading hole, the bit slips against edge of hole in the tuner plate). The mounting screws (with conocal bottom) forced the plate 1/32" up the headstock from the "loose" position once they were tightened and caused the posts bind in the headstock holes (that's why I don't use stepped holes in headstock but straight cylindrical holes to fit bushings) and excessive binding between bottom of tuner cog and the plastic washer/metal strip underneath. Someone tried to help teh tuners in the past but he managed to assemble the metal plates upside down (the edge that holds the worm is slightly bent) and that caused part of the plastic under worm wear away on all 8 tuners. The tuners were assembled with screws loosened a bit to reduce at least the binding of the gears. I replaced the plastic washers with similar material, reinstalled tuners and drilled new holes for mounting screws. Now the tuners turn much better htough not perfectly smooth as the plastic I used is not the self lubricating stuff of originals but I guess it will last few years without the excessive tension.

[dhergert]

Wow, very very impressive. Great, exacting work, such as a F9, or possibly even some more pricey models from this period, normally would never see.

Thank you for sharing these great details and your expertise...

Since in your examination it doesn't seem that heat damage caused the loose dovetail joint, it sounds from your description and looks from the pictures like this assembly was just poorly done in the first place. Were there signs of any other extraordinary stress or damage that might have contributed to this problem?

As others have mentioned, it would be very interesting to hear or get reports about how this basically re-built F9 sounds. Again, wonderful work!

[HoGo]

This will be tha last post...
The nut was typically barely over 1" wide with strings spaced right to the edge of frets. I noticed the headstock angle was cut slightly ascew so the fingerboard gluing plane meets the headstock surface almost 3/16" north of nut on the bass side and 1/16" on treble side. The space under the headstock overlay next to the nut was filled with black filler and looking from headstock towards body the overlay looks 1/16 higher on the bass side of the nut. This is purely cosmetic but I expected a tiny bit more precision in these simple tasks. There were more details that were not cosmetically on par with higher models, like the end of fingerboard that was cut off down the middle of the fret slot and the edge of the slot was still visible through the finish, same on nut end. etc.
Here is last batch of pics...

I will upload a sound sample later.

[HoGo]

OK, below is link to sample taken right after first tuning up to pitch with fresh set of J74's. The sound is a bit twangy, it settled a bit few hours later and I tweaked the setup a bit more as well after the mandolin settled down (truss rod needed tightening). The owner took it out of my hands a day later so I didn't have a chance to record it again... I think he is quite happy with result, it's got plenty of bass, mid and treble and good chop to boot. And with new setup and frets it's joy to play.

http://gjgt.sk/~minarovic/F9.avi (It's just simple vid from my compact camera)

[HoGo]

What's interesting to me is that the close up of the top scroll where you can actually see the binding, it looks like one of the more accurate scroll binding jobs you see from Gibson except you can't see it since it's black in the sunburst. Then you see a Master Model and it will have a hawks-bill look. Wierd.

Yes Jim, this one had one of the better scroll binding joints though without the strong light of the flash you could just see the cracked glue lines telegraphing through the finish and the IMO crude carving of the scroll at the joint but once I carved it to the style of Loars there was no "eagle beak".

[sblock]

Jeez, the neck had been mounted incorrectly, the f-holes were off, the bridge was off, the top carving was irregular and not carried out to the edges, and on and on.

It sounds to me that this Gibson F9 was a rather poorly made instrument, at least by the standards of today's better luthiers. Shame on them, I say!

We should not hold Gibson in such high esteem when they produce sloppy products like this. You wouldn't expect to see this level of sloppiness in a Weber, Collings, Mowry, Pava, Northfield, or other contemporary F5 instrument in a comparable price range, around $4k.

[Tom Haywood]

Than you, Adrian. This is very helpful.

I did some work on two new F9s in 2008 or 2009 that also had neck joint and alignment issues with related bridge issues and sloppy F hole alignment. The mandolins sounded great and they played great after fret board leveling and installing new larger frets. But the factory new condition spoke loudly of cutting corners and doing very inferior work. Your photos show that it was likely much deeper than I saw at the time.

[Charles E.]

HoGo, that is an impressive rebuild. Did the repair work cost the owner more then the original price?

[dhergert]

Personally, this is more convincing evidence that the higher quality new mandolins -- at competitive prices -- are coming from boutique builders.

I do still like my "rustic" old F9 a lot. And somehow I do still like the Gibson name, maybe because of favorable experiences, and/or maybe because of brand recognition at sale or trade time.

But ever since I bought a blowout $199 Pacific Rim F-style mandolin and compared it detail-for-detail with my F9, I've been looking more admiringly and more wistfully at boutique builders for a lifetime instrument that I'd never want to sell or trade off.

[Br1ck]

I got to play an older and a new F9 at the Mandolin Store recently. Can't remember the age of the used one but this century for sure. The older one was pretty good, the new one exceptional, but a lot of money for what others are doing for 2/3 the cost. If you gotta have that Gibson sound though........

[HoGo]

HoGo, that is an impressive rebuild. Did the repair work cost the owner more then the original price?

No it didn't. Mostly because he got it for VERY good price and we are not in the US... I can tell you it has approx. 90 hours of work in it. I was not particularly fast and do ALL the work with handtools old fashioned way but I don't charge anywhere close to US makers.
Just for comparison, I copleted F-5 StewMac kit for owners' FIL (that he gave up after few first steps - he just glued kerfing and roughly cut one f hole and messed the scroll cutting -that's where he stopped) and that took me less than 70 hours to complete.
Sometimes it's easier to build one from scratch than repair or undo lots of others' poor work.

If you gotta have that Gibson sound though........

Are you talking about the vintege Gibson sound or the modern one? With those back graduations and deep scoop at he scroll block the sound is significantly different from Loar style graduations.
Mandolins like this F-9 (as originally built with overall thicker tops and small bars) have stiffer feeling under fingers and can be played very hard (OK, you HAVE to play it hard to get volume) and the back without the thick area (even if the edges are thick in average it weighs teh same as normal back) gives it the missing bass support and chop that folks like. Modern traditional BG players like (or even prefer) this type of sound over true "Loar sound".

[Eric Oliver]

Just like a kit...only worse.

The owner was lucky to have you as a resource.
He has a really nice mandolin now.