Monday, 14 January 2013

Gibson Southern Jumbo 1955 - Re-build

The Gibson Southern Jumbo is a great guitar, I wish I saw them more often.
This lovely old instrument had the misfortune of spending a huge part of its life in a damp garage. As far as her new owner knows she sat there since 1976.

You'll notice there's no serial number on the back of the head. Gibson often omitted individual serial numbers on their less expensive models. On the neck block the 'W' denotes 1955. It's called a Factory Order Number (F.O.N)

 My first job is to assess it - there could be a lot wrong in here.

 I took the truss rod cover off first and ... no truss rod!
 It had snapped off - maybe this is why it ended up in that garage.
 A closer look showed me the cavity the nut should sit in has been gouged out, I'm guessing to accommodate a socket set to adjust a stiff truss rod nut.
Now that would do a good job of snapping it.
Maybe I should have been an archaeologist, I love this stuff.

So I know at the very least I'm going to be taking the fretboard off to fit a new rod and do something about all the wood taken out of the headstock.

  The finish is scruffy but original and there are a few big splits in the top.

 The tuners are in need of a clean and a lube but work really well.

The back is ok except for lacquer cracks.

 But most of the back is coming away from the sides and the binding is missing.

The heel is coming away and the neck/body joint is loose.

 Looking inside with a mirror the bridge plate is worn and there's evidence of damp.

This back brace is coming away.


This one too.



The wood of the bridge has been shaved down at some point to try and lower the action. It clearly needed a neck re-set, this is a common bodge I see to avoid doing it properly.
 It's a shame, the bridge is Brazilian Rosewood. 
 The dot inlays (hiding bolts) almost vanished when the bridge was shaved.


The bridge saddle is sitting in some yucky goo.

 On the bright side - the headstock hasn't been snapped off. Hmmm

 Just about everything else is wrong though.
 My main concern is the evidence of damp inside the body. But there is so much wrong with this one.

This guitar is in a sorry state.
 It's sad it got to this point but the new owner is determined to have this as his main guitar. 
 This one is going to take a bit of figuring out.

 Sam's keen for me to use it as his new throwing stick.

 Ok, here's the plan:
Fretboard off
Replace truss rod
Fill the gouge in the headstock with mahogany
Take the neck off so I can re-set the angle
Take the back off (it's coming off anyway)
Take all the braces out, clean them up, put them back
Replace the maple bridge plate (make a new one)
Take the bridge off, heighten it with a piece of rosewood
Fix the splits in the top
Put it all back together
Bind the back

I put a quote together and the owner says 'yes'.

Ok, let the fun begin.

Sorry Mate, maybe next time.

First the endpin comes out - amazing how it has become discoloured - I think that's fossilized selotape.

The tuners look a bit scruffy but work fantastically.

Before taking the neck out I'm going to take the fretboard off. This will give me easier access to the neck/body join.
I'll need heat to remove the board. But first I need to take the inlays out. They're plastic and could melt with the heat.

I careful remove them with a blade.

And lay them out on some masking tape ready to go back in when I need them.

I protect the body from heat using foil covered lino.

I protect the binding with two layers of masking tape.

I use a purpose made neck heater  - fancy eh. It even has a temperature control.

After a bit of heating and some encouragement from the butter knife the board comes off cleanly, binding and all.

Gibson had cut grooves on the underside of the board to help adhesion. Rosewood can be a bit resistant to gluing sometimes - it's rather oily wood.

And here is the neck/body joint exposed. The thin maple strip down the middle of the neck is the fillet strip under which is that snapped truss rod.

 There's no easy way to remove it undamaged - I just dig it out. I can make a replacement one from maple later.

Here's the rusty old truss rod.

 At the butt end it bends down to an unusual anchor. I'm not going to be able to get it out before the neck is out of the body.

I remove the neck using steam in the usual manner. Here's some more info on that process:

Here's the neck join after the neck is removed. You can see the top is coming away too.
And the back.

Ok, back to the neck. I need to sort out the cavity where the truss rod adjuster lives before I can put a new rod in.
The neck is made of mahogany so, of course that's what I'm using to fill the hole. There's the piece I'm going to use sitting on the headstock.

I carve it until it fits nicely and glue it in using alaphatic resin. The little piece of clear plastic it to stop any glue getting into the truss rod channel.

Once the glue is dry I carve the top flush to the headstock. This is all going to be covered by the plastic cover plate but I want it to look neat anyway.

 Now I need to carve the new space for the truss rod, its nut and with just enough space for a Gibson spanner.
 You can see the new truss rod (with the blue sleeve) and the Japanese saw I'm going to use.

I'm using the existing truss rod channel to guide me and a wee piece of wood to keep the saw straight. Japanese saws cut on the pull stroke and are way more accurate than western saws.

I clean up the slot with a small chisel.

 Now its carving the space for the adjusting spanner.
I use a gouge for this. I have a few fantastic, old gouges that were very kindly given to me by one of my customers. They had belonged to his grandfather and he was just keen for them to get used again. There's a lovely connection people feel towards old tools, even if they don't use them themselves.

 Here it is, that's all I need to do - someone had removed a lot more than they needed to.

 I'm happy with how the new truss rod sits in there. The blue plastic sleeve over the rod is to prevent it getting glued in which would prevent it from working.

At the butt end I've copied Gibson's method of anchoring the truss rod.

 I make a new fillet strip, glue it in, shave it smooth with my cute little thumb plane and that's the truss rod fixed. Still a long way to go until the guitar's finished.

I removed the old bridge saddle, filled the hole with rosewood and re-routed the slot to the proper size. I remove the bridge from the body so I can re-glue it properly.
I seem to have forgotten to take pics of all of it - must have been concentrating.

Now for the body. I take the back off using the butter knife - it doesn't even need any heat - that's what the damp has done.
 It doesn't look good in here.

The neck block is surprisingly rather wonky - bit dodgy that Gibson.

I clean it up and clamp a piece of mahogany to it so I can make it square.


There are a quite a few rather sloppy joints in here. This bridge plate should be butted up to the 'X' brace. The smaller brace should either be butted up or cut into the bigger one.
I find lots of examples of shoddy workmanship.

There are lots of places where the moisture has caused obvious damage.

The bridge plate has a lot of wear at the string anchor points as well as not fitting very well. It's such an important part of the guitar I'm going to replace it. I'm keen to keep everything as original as possible but this just has to go.

The back shows the same water stains as the underside of the top.

 This is when the real fun starts. Time to take all the braces out.

Under this back brace I find a pencil line put there in 1955 to mark where the brace goes.

I clean the old glue off with a cabinet scraper.

The centre strip is coming away a little to I pack it with glue and clamp it down using the 'go bar deck'. I've used a damp rag to wipe away the excess glue.

All the top braces come off using only the butter knife.

There's a fair bit of work in cleaning up the mess before it can all go back together.

The meeting point of the 'X' braces is one of the most important areas for structural strength. It's a common place to see splits.

There were some big gaps in this joint - (I'm really not impressed) so I added a couple of small wedges and glued a cap over the join to keep it strong.

I made a replica bridge plate - just a wee bit bigger so it will butt up to the "X" brace for a stronger join.

And now she can go back together. Firstly where the top was coming away at the neck dovetail.

Then once the braces are cleaned up they all go back in using the 'go bar deck'. The base of the deck is dished to a 28" radius - flat top guitars are not flat. This slight curve gives the top a lot more strength.

You can see I've repaired a couple of splits in the top using cleats for extra strength. It's stuff I've talked about before so I won't go on.

Then I pop the back on.

I re-route the binding channel and bind it.

Just a case of popping the neck back on, fret stoning and setting up. It's all stuff I've covered before (and I forgot to take photos of that bit anyway).

I strung her up with D'Addario 12's tuned to concert pitch.
I was very interesting hearing her for the first time. In the first 10 minutes from being strung up the sound changed hugely. It continued to change but less so for a few days. This is exactly what happens to new guitars, it's amazing to hear how they 'bed in'. That first 10 minutes is an exciting time.

 I was very pleased with the result - she just sounds fantastic.
You never know what the end result will be with this sort of job. I just do the best work I can and hope the beautiful old, seasoned tonewoods do the rest.


I am no longer repairing guitars - since covid 19 I now work full time making pickups