Cocobolo/Adi Dreadnought

[Bob Connor]

I thought I'd detail the construction of this instrument so it's owner can keep track of it's progress and I can make some notes on how the Coco works.

Both the top (Adirondack Spruce) and the back and sides (Venezuelan Cocobolo) came from Bob Cefalu at RCTonewoods.



You can see that the Adi top has lots of late growth in it (the dark stripes) which makes it extremely stiff. It also makes it a lot denser and heavier.
There is up to 120 grams difference between some of the Adi tops I have.

The top was joined using a Jet jointer. I then put some 3M Stickit sandpaper on to the bed of the jointer and make a couple of passes of the top on the sandpaper (which generally ensures a tight joint)

The Cocobolo is extremely oily and will clog up the paper on your drum sander in no time at all.

I keep a roll of 40 grit paper just for jobs like this. It will get your wood down to thickness reasonably quickly without clogging up like 80 grit does.

In this case I was thicknessing the sides which I wanted to end up at .080". I took them down to .095" with the 40 grit and then swapped to the 80 grit to end up with the dimensions that I wanted (which ended up around .081"-.082")

I then sanded with the random orbital with 120 grit before bending.

I used my now standard procedure for side bending, which is to sandwich the sides firstly in kraft paper, the spritz lightly with water and then wrap in aluminium foil.

Then heat the sides in the Fox bender, starting the lower bout bend when the temperature hits 100c. Then do the upper bout and finally screw it all down. Watching the thermometer allow it to reach 150c and them turn it off and allow to cool.



This Coco bent easily with very little springback.







The next step is glueing in the neck and tail blocks. We used to do this in the mold but it proved problematic so we now do it before insering the sides into the mold.





So far I've had no reaction to the Cocobolo.

Thanks fer lookin'. To be continued

[ozziebluesman]

G'day Bob.

Looking forward to watching this one grow. I am keen to see how the Cocobolo behaves! This post will be useful for me later on when I use my set of Coco.

Cheers

Alan

[Allen]

I've heard some people have experienced problems with glueing Cocobolo. Ire you doing anything special to deal with this possibility?

[Bob Connor]

Next we need to put the sides into the mold and shape both the back and top with 15" radius for the back and 25" radius for the top.



We converted an old potters wheel.







The next step is to flatten the upper bout so that the 2 degree neck angle fits properly and there's no 14th fret hump.

I built this jig to do the job. the tail block sits on a piece of wood 1/8" thick.










The next step is to install some cloth strips on the guitar sides to prevent the spreading of cracks in the event that the guitar gets a knock on the side. I haven't got the strips yet so I'll make the kerfed linings ready to be installed over the cloth strips.

This is a simple jig the sits on our small bandsaw. The depth of the kerf is varied by by adjust the upper blade guides back or forward and the cut is done by aligning the pencil mark up the the jig by eye. ie no indexing pin.

[Hesh1956]

Great looking guitar Bob my friend. That coco is beautiful!

When are you going to clean that shop - must be hard to find Le Fridge in there.....

[Mark McLean]

Cocobolo makes me cry!
Yes, because it is beautiful, but also because I got some dust in my eye last week and I had raccoon eyes for 7 days. Needed steroid drops to get it to settle down. I used it last year without any problems but the sensitivity can develop late - so take care. But those sides are stunning!

[Bob Connor]

Allen

I'm going to use epoxy to join the back plates.

[Hippety Hop]

Good stuff. I like that idea of flattening the upper bout after radiusing.

Cocobolo looks good. Anyone tried it for fretboards?

[Bob Connor]

This ones going to have a Coco fretboard Hip

[Kim]

Sexy coco Bob, did you pick that set out urself when you visted BobC??

Cheers

Kim

[Bob Connor]

Sexy coco Bob, did you pick that set out urself when you visted BobC??

Cheers

Kim

Sure did.

[Bob Connor]

Today I took myself down to the local haberdashery shop to buy some bias binding. This is for reinforcing along the guitar sides to stop any cracks spreading further that they should.

Previously I've used wooden ones or in small instruments none at all but I thought I'd give the cloth a go considering that it doesn't weigh too much and the fact that the Cocobolo is bloody heavy.



Next I throw the kerfed linings into the Fox bender not so much as to bend them but to heat them up and make them pliable. They'll get a spritz of water before they go in.

Once they're cooked ( I'll start bending them at 80 C and once the bend is completed turn the blanket off and leave for about 5 minutes.

While they're still warm I'll dry clamp them into the sides so they'll conform perfectly and also to allow them to dry out completely. (We've glued them before when they were still damp and the glue joint came apart.)



Once they're dry we'll glue them with Titebond and clamp.



While all of this was going on the back plates were joined.

I took the liberty of throwing in a piece of decorative backstrip.

Allan, who'll be the new owner of this weapon was admiring a similar one in my Hondo Rosewood OM, plus I thought it may be better to glue the Coco to the Maple backstrip rather than Coco to Coco given the problems that a lot over people having glueing this wood.

I didn't wipe the joint with acetone or anything. Just glued the two back plates as soon as the joint had been done on the jointer.





Things may slow down a bit now as I'm waiting on a piece of Cocobolo for the rosette fro Uncle Bob. I've got one here but it's warped and I'm sure it'll crack if I try and do anything with it.

[Hesh1956]

Great looking guitar Bob my friend. That coco is beautiful!

When are you going to clean that shop - must be hard to find Le Fridge in there.....

[Bob Connor]

The shop has that "lived in " look at the moment.

Never fear Hesh. Le Fridge is always accessible.

[sebastiaan56]

Hesh,

That is a clean shop..... by my standards anyway...

Looks nice Bob, does Cocobolo have any sonic properties to compliment the bling factor? It sure is pretty,

[Bob Connor]

Sebastiaan

Cocobolo has that typical glassy Rosewood ring that has long been associated with Brazilian Rosewood.

A lot of builders believe that it and Honduran Rosewood are drop in replacements for Brazilian.

Unfortunately both Cocobolo and Honduran Rosewood are likely candidates to get CITES appendix II listings in the near future.

They already have Cites III listing as one country (Guatemala) has asked for assistance in controlling the trade of that species.

There's a full listing here.

CITES appendices

[DarwinStrings]

You are prolific Bob and you manage a full time job as well, I'm surprised you even get time to drink beer. The old potters wheel is a interesting contraption, I saw the pic before I read your text and thought you'd been putting you guitars in a washing machine. I would like to know where you got those small colourful clamps as I can't find any like them and would like to add a few handfuls of them to my kit.

Jim

This forum doesn't like the way I spell colour, I refuse to comply.

[Taffy Evans]

Thanks for the progress reports, what can I say. When one gets in late it's all been said, I agree with all the other viewers, great stuff.

Jim...I got two buckets of those clamps [they came in plastic ice creem type buckets] from bunnings.

[DarwinStrings]

Thanks Taffy

I might have to take Bob's pic into Bunnings and do a "special order" ( that means a order that takes a month then gets sent to the wrong store ) as I have never seen them here, I have a stack of larger peg type from Bunnings but those small ones look handy.

Jim

[Lillian]

Jim, Bob does some amazing things, no doubt about it. But just so you know, he has a silent partner, Dave. I have seen pictures that Bob has identified the individual as Dave, but I don't know if Dave has ever posted to the forum, hence the silent, if so it was a long long time ago and I have slept since then.

[Bob Connor]

Funny you mention it Lillian but Dave was in the shed today so I got photographic evidence. He's been busy with other things the past three or four months so I've been flying solo up until now.

We've got quite a few instruments to finish before the Port fairy Folk Festival.

[Bob Connor]

I took the back out of the clamps this morning and thicknessed it down to .090"



Then marked out the back brace positions. I know the bottom one looks way off but it's where I picked up one of the back braces and the chalk came off it.



Radiused the back braces to 15". These are Engelmann Spruce and I cut most of the radius with the bandsaw before using the radius dish. The braces are 8mm wide. On smaller guitars I use 6mm.



I scallop out the ends of the back braces on the belt sander before glueing.



I used Hot Hide Glue for the back braces on this one. Normally I'd use Titebond but I thought I'd see how the HHG goes with Coco.

[matthew]

Loving watching this in real time Bob.

Funny, the thought of starting a guitar fills me with trepidation. Your posts make it easier to contemplate.

[Hesh1956]

Bob my friend Dave looks like he is enjoying himself.

Has Dave ever posted on the ANZLF? If not perhaps you could get him to drop in and at least tell me to piss off?

[gratay]

thanks, I'll be watching with great interest..

Cocobolo is so stunning...I think with a cocobolo fingerboard that will be a real looker.