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Unwrapped! Tom's African Build


Andyjr1515
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I’ve mentioned a few times in past threads a project that I've been putting time into that was ‘under wraps’.

Well – it is time to reveal all! :)

This has been a journey of exploration – design wise and building techniques wise – that I think and hope a number of you may find of interest.
Even though the bass is now pretty much complete, I will post this as a standard build thread and not reveal the final bass until the end.

It is a bass for Tom, our very own wwcringe.

Tom will add to the thread in terms of the background, origins and motivation, but my own involvement came in during a meeting on a Derby station platform last year after Tom had contacted me through BassChat. Tom wanted to meet to talk through ‘one or two thoughts’ he had of a possible build.

At Derby station, we had an interesting chat about a number of topics (including violas!) and then he rummaged around in his bag and pulled out this:









It was a bass body-shape made for him by some of his contacts in Africa following a conversation during one of his previous visits there.

It’s a very pretty piece of wood but there were some immediate and obvious concerns:[list]
[*]it was unclear exactly: what the wood was; what its strength was; what the tone might be; how stable it was
[*]it was only 1” thick at its thickest ...and wavy...and uneven. The bottom of the neck pocket was less than 7mm thick
[*]the carve was skilled, but had been done without knowledge of some of the specific critical dimensions needed in a bass build;
[*]oh and yes, the neck pocket was too wide and too shallow to fit a standard neck anyway
[*]in fact there wasn't[u] actually[/u] enough depth to fit a neck pocket...or pickups...or electrics...or jack...
[/list]
So all in all, there wasn't much chance of this being built into a bass at all... and even less chance of it staying in one piece. And even if it could be and did, would it sound like a ham sandwich?

So, with all that, Tom asked, was Andy interested in taking it on?

Yes - [b]of course[/b] Andy was interested in taking it on! :lol:

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But of course there are those who say the wood has no influence on the tone of a guitar.

But then again there are those of us who actually play the instrument who know it makes all the difference.

[steps back slowly in the hope no-one read that] :D

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So the first step was to decide whether this was feasible in the first place.

What was perfectly clear was that a bolt-on neck was simply not going to be practical. There was no way of knowing how strong the African wood was...there were already cracks appearing in it...and, in any case, there simply wasn’t enough thickness for the neck itself and anything (however strong) to support it. That lead to basically three options:
[list]
[*]To flatten the back of the African wood and treat it as a drop-top to a fairly conventional mahogany or similar back. Feasible, it would work, it would look nice, but would end up as a ‘conventional’ drop-top bass.
[*]To go for a visible through-neck, splitting the body either side of a laminated neck. Feasible, it would work, but much of the visual appeal of the wood would be lost due to the prominent through neck running the length of the body.
[*]To see if it was[b] at all feasible[/b] to slot the back of the body and set in a through neck, leaving the body visually complete from the front (similar to how I will be doing the Bubinga build on my other thread) and retaining the appeal of this particular piece of wood - which was its very slenderness and wavy unevenness.
[/list]
It was this latter option I decided to explore further to see if it was even possible, given the dimensions.

I traced round the shape and measured the thickness along the length of the body. Many rough sketches later, I was able to send Tom this as a concept:






I could see lots of challenges ahead but – well – it just might work.

Basically, the proposal was build a 'loaded' neck – everything that mattered for strength or functionality bolted to the neck - and slot the African body over it purely as decoration. I can fairly confidently say that you are unlikely to find this approach in any ‘how to design build a guitar or bass’ book – and probably with very good reason!

Through exchange of a number of emails and sketches, Tom and I agreed that it would be worth a shot...but we were both well aware that the chances were high of complete failure. So, rather than posting a car crash in slow motion, we decided it would probably be best to keep the project under wraps until we knew what we were dealing with...

...and, boy, there was a lot we were dealing with!

Thanks for looking :)
Andy

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So it was agreed. Through-neck, slotting the body and laying that over the neck, with everything else possible bolted to the neck.

Even here there were some challenges:[list]
[*]How deep would the pickup be? Including any wires, the body was possibly going to be only a few mm deeper than the pickup chamber...
[*]...which would, of course, cut right through the neck wood, separating the bridge from the neck (the continuity, of which, was the whole point of the through-neck)
[*]There would be no room for pots, so it was going to be straight from pickup to jack
[*]From professional experience, Tom’s preference was to use a Neutrik jack socket...now where was THAT going to go?
[/list]
The drawing said, though, that if everything was accurate enough, there would be JUST enough strength left to hold the thing together, providing the African timber was strong enough in the right planes and directions...and more of that later...

But, whatever the drawings indicated, everything relied on the neck so a start was made :D

Tom and I had agreed maple / colobolo / maple would provide a nice contrast, with a colobolo fretboard and headplate.

I cut a maple blank in two, oriented it for strength and twist resistance and flattened it with sandpaper double-sided taped to a long straight aluminium beam.



The cocobolo inner splice was to be joined in the centre of the neck and also scarfe jointed at the headstock end with the maple cut straight-grained. The theory here was to gain a bit of head-break resistance (including a modest volute) without a visible scarfe in the maple.

I sanded the cocobolo and did a trial fit of the mating surfaces, including the centre overlapping join of the cocobolo:



I was chuffed with this as it is the first time I've tried 100% hand-tools for this job

I talked about sanding the cocobolo...here came the next challenge. Cocobolo is an absolute pig to work with! It is very oily and clogs up sandpaper and tools with a glassy waxy residue very, very quickly. More concerning, given the strength fears with this build, is that cocobolo is also difficult to glue
.
Some internet recommendations include wiping with acetone and then use normal titebond or similar - my test pieces failed gloriously with this method. Alternatively, and with a general concensus of more certainty, was gluing with epoxy!!!

The concern with this build was always going to be strength, so epoxy it was. Lots and lots of 'proper' clamps later...



(Note to self: I really must build some sort of workshop! :rolleyes: )

The cocobolo had already been scarfe-joined before sandwiching, so last task was to simply lop off the excess maple from the top of the headstock area:




So now we had the makings of a neck...and no more excuses by Andyjr for procrastination...

Thanks for looking
Andy

Edited by Andyjr1515
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It was about this time that I began to notice the cracks...or should I say how many more there were and how quickly they were growing. :o



On closer inspection, they were everywhere, mainly coming radially down from the edges of the darker figuring. The main bulk of the body seemed quite rigid, but I realised that the sooner the neck slot was done and the neck at least in position, the less likely that the body would fall apart during the machining...bearing in mind, to end up with a decent neck depth, the slot would have to be routed to within millimetres of the (wavy) top.

So the next challenge was exactly how to clamp it and how to rout it, with both the bottom and top faces being uneven. Luckily, sitting on its face the four or five high spots left it sitting relatively flat. I built a mini sliding rig for my fabulous little Bosch router and mocked up how this might work.



The body would be held (vaguely) with double-sided tape, but the clamping would need to be done using packing slivers to fill the various odd shaped voids underneath so that all the clamping force would be vertical rather than distorting the body around its central spine as the body material was removed. This had to be avoided at all costs because it would, at best, create an angled slot (bad) or more likely, at worst, break the back of the body (very bad).

It was also a bit distracting because, all this time, Mrs Andyjr1515 was stomping around the house looking for the full length mirror that she was SURE was in the spare bedroom last time she looked. Still, I had much more serious stuff to deal with out on the patio...





I couldn't put it off any longer...fingers crossed...

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[quote name='paul h' timestamp='1431939596' post='2776298']
Fascinating stuff. Can't wait to see it finished!

(Personally I would have planed the back and used it as a top. Just sayin')

;)
[/quote]

Hi Paul

Yes - as outlined above, that was one of the options considered but, as someone once said about our band's playing, "Andy, what I like about watching your band is that you're all always on the very edge of disaster...very exciting!" :lol:
And I think we were only playing Kum By Ya!

I think maybe some of that has rubbed off on my guitar and bass building :rolleyes:

Edited by Andyjr1515
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I like your style :D

Funnily enough, about 25+ years ago when I was a huge Kiss fan I considered getting a some kind of cheapy cricket bat/steinberger copy and making detachable axe shaped "wings" for it...which is not a million miles away from your approach.

I always thought it might make a feasible commercial product...a bass with exchangeable body styles.

But anyhoo...looking forward to the end result!

:)

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To my relief, the timber held up well to the routing. You can see here JUST how close I would need to get to the top...no choice or there simply wouldn’t be enough thickness for the maple and its much needed strength.




The fall-back position here, it it was to finally give up and break its back, was going to have to be a visible neck top and African timber wings (and hopefully not detachable in the style of Paul h!)

The rout was finished, the body was still in one piece, the measurements were checked and spot on.

I then heard a tiny *click*. Now - those of you who do luthiering – or any type of woodwork – will know that unexpected *click*s are not good. :huh:

My *click* was accompanied by the African timber-language version of a *sigh*. The kind of *sigh* one might let out when, having worn trousers that were too tight all day for a formal occasion, you finally can loosen the belt in the evening and undo the top button.

This was the result of the *click* and the stimulus for the *sigh*:



B****r!

But after all that thought and effort – and the fact that, against all the odds, the bulk of the top was for the moment was actually holding good – I didn't want to immediately revert to plan B of body and wings. That could always be done later if the situation was not recoverable.

There was no time to take photos, because I could not be at all sure that the crack was not going to keep going. It was time for some quick logic and some quick action. The logic was:[list]
[*]Visually most of this area will be cut away anyway to fit the fretboard over
[*]Strengthwise – once the neck was glued - then there would be nowhere for anything to go and all would be stable
[/list]
BUT[list]
[*]It would be sometime before I could actually glue the neck. This build has no room whatsoever for ‘normal’ tweaks and adjustment of heights and angles – the neck could only be glued once all of the other datum points had been established – neck position, bridge position, neck angle, fretboard height, etc, etc
[/list]
I had to stitch it together therefore, long enough for all of that to be done (maybe weeks). It had to be something thin also enough not to get in the way of the routed slot. 1/64” ply would have been best, but I didn't have any handy.

What I did have was some veneer left over from Bryan’s Thunder Jet bass job! I mixed some quick setting epoxy, popped some into the crack and laid the veneer, cross grain, over the whole area.

After all that, was the neck (including some additional cocobolo side strips which I will explain later) going to still fit?

Yes





Phew!
...and isn't that better than a visible through neck and wings?

...admittedly the neck's a bit chunky, but I'm sure Tom will get used to it... :)

Edited by Andyjr1515
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So why the two cocobolo strips running along the body either side of the neck?



Pretty much everything related to this build has had to start with finding a solution to a functional necessity and then working the practicality and aesthetics around that.

The bridge (using one of Tom's old Ibanez's as a donor) is wider than the neck and, as such, the two outer screws would have gone into the body wood, rather than the neck wood. The cocobolo strips would mean that the bridge could be fully secured in sound, stable and predictably behaving wood.

On the other side, though was another problem:



The neck pocket carve - although most of which would be routed away depth-wise - was actually wider than both a neck and the extra cocobolo strip:



Here, the area would need to be turned into a 'feature' with a piece of cocobolo carved and set into the space.

That could wait, though. I needed to get the neck position firmed up - lengthwise and height-wise - so that I could get it glued in and the whole assembly stabilised as soon as possible...


Thanks for your continued interest and patience! :)

Andy

Edited by Andyjr1515
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[quote name='owen' timestamp='1432067996' post='2777912']
I am loving this. I would love to have these skills.
[/quote]
It's more making it up as I go along actually, Owen :D
Each step of this build has been preceded by a week or so just looking and thinking 'how on earth am I going to do this?!?' Often, the answer became easy simply by the elimination of all the other options!

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Tom wanted a trussrod and also carbon rods for stability of the neck. As we were talking of the possibility of asymmetrical neck profile and also the extremes of temperature and humidity the bass is likely to be exposed to (it will be hopefully shortly going on tour in Africa!) it seemed a very good idea.

My preference is to go for the simple rod and strip truss rods - less to go wrong. I routinely test them before fitting. The only thing that could fail is the weld, so I pop them in a slot, clamp them in a workbench and stress them way beyond normal usage.

The other thing I try to do is to make them removable! I really don't understand why the main manufacturers don't do the same. With this particular design, the back of the truss rod does not widen as in some others:



So to install - before applying the top cap, I simply overlap a strip of plumbers ptfe tape which does three things:[list]
[*]keeps the glue off the rod
[*]stops any rattles
[*]eases the ability to slide the rod out in the future if needed
[/list]
To remove the rod, it then just needs a decent pair of needle-nosed pliers, grabbing the adjuster between the allen key hole and the o.d., sharp tug and out it should slide. Take new rod, wrap ptfe tape round and slide back in.
Because the headstock has a facing plate on, this would need to slotted a little to allow the rod to pass and you might therefore need a longer truss rod cover after the operation - but nothing compared with the hassle of the alternative of removing the fretboard!



Anyway, back to the build.

A process of check, double check, double check the double check went on to determine a number of factors, sliding the body forwards and backwards on the neck and placing the actual bridge and a spare representative pickup in various positions





Once the neck is in and glued, that's the end of it if anything is wrong. The checks were to determine:[list]
[*]The correct position for the neck, bridge and pickup. Tom wanted a 34.5" scale, fretless and, to prevent neck dive as much as possible, I wanted the bridge to be as far back as possible, to be able to shorten the neck as much as possible. The combination of not much body mass and long scale made that quite an important factor
[*]Whether the neck needed a dogleg slot to raise it at all. Once the bridge position lengthways was determined, I knew which bit of the wavy top the bridge was going to fit. This allowed me, placing the fretboard onto the neck, to place a straight-edge along the board to the bridge to see if the neck needed lowering or raising in its slot.
[*]Whether the neck needed angling or not.
[/list]
A bit of luck was on my side here. No angle was needed and - if I'd got it right - once the body had been flattened to give the bridge a firm base, the fretboard height would be OK without the need to step or deepen the neck in the body area.

The slots for the carbon rods were routed and the neck could now be rough shaped ready for gluing:




It now could be glued in and the whole thing stabilised and less likely to form the basis of an unusual combination of smokes on the BBQ :D


Andy

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