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John,
One thing that I have noticed with Cocobolo is that no two sets are alike, unless there cut from the same board. I have five cocobolo guitars going right now and I think maybe two are close to the same "oil" factor
The little 0-12 I did was very dry, by comparison one of my OMFS' I'm doing bleed like crazy!
So I tend to think that what works for one set, may not work for the other. That is unless its epoxy

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Lance@LuthiersForum.com

Glad me and cocobolo don't get on (allergy wise) saves a lot of heartache!

I have used it for headplates and bridges, always glued with hide glue, the bridges are still on. I do always run a scraper over all surfaces just before I apply the glue.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

[QUOTE=Hesh1956] I have never built with coco yet and have been watching here with great interest. I have to tell you though that this is not very encouraging. To me the thought of a brace popping off is a nightmare.......

Andy I like your new sig!! [/QUOTE]

Don't let any of this scare you. Cocobolo is one of the best woods going. Just use epoxy.. you will be fine.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

I have built more with coco than any other wood (koa runs a close 2nd)and is my favorite t build with. Never a problem. Havent used acetone or any other thing on back joins, braces or whatever may be gluing. Use titebond, except for binding and then use CA. If do anything out of ordinary and don't know if makes a differnce at all is let it sit longer on back joins before doing anything else.

I remember a Fine Woodworking article about gluing exotics, Rosewood, teak and others (I'm not sure if they included cocobolo).  They cleaned the joint with alcohol, naphtha or other solvents OR they sanded the joint.  After cleaning or sanding they glued  them with AR glue.  They then tested the breaking strength of the joint. The sanded joints were consistently about 1/2 again or more stronger than any of the cleaned joints.  If there is interest I can go through my piles of mags to find the article to provide details.


Kirby

I did a simple experiment after buying some killer coco from the Zootman-
I prepared 3 2x2" squares of 1/4" cocobolo by sanding to 220 and then wiping clean using a residue-free tack cloth without solvents. I then glued each piece to a slab of similarly prepared mahogany with LMI Luthier glue, standard Titebond, and 1-hour Stew-Mac epoxy. I then clamped to the point of squeeze-out and then let them dry overnight at room temperature. The following day I tested the bond by pushing a 1" chisel into the joint line and then lightly prying.
The LMI- glued piece popped right off with no attatched wood fibers. The Titebond piece came off easily too, although there were some adherent wood fibers on both pieces. The epoxy piece held firmly and would not separate along the glue line.
My take on this simple non-scientific experiment is that epoxy is the way to glue this beautiful but problematic wood. Although many experienced luthiers use Titebond (Charles Fox among them), does anyone have long term data- how these instruments will hold up 20 or 30 years from now? Just curious.
By the way, Art Overholzer soaked his BRW in some aromatic hydrocarbon brew, changing the bath periodically until it no longer turned dark. He also glued at least the the top bracing with epoxy, using weights instead of clamps to achieve a "stress-free" acoustic system. Not to try to dis Art, but I believe his "Grand Champion" was awarded a ribbon in a local, not international contest

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It's not the miles ahead, it's the stone in your shoe


In Markham,Virginia

Jon
Your post got me wondering about my defective memory so I rechecked the Overholtzer book and found the references to the soaking proceedure. He used spic and span in water and soaked for a week, changing the water daily. He said the water would turn black and thick each day. On the seventh day he just boiled the sides and though it was still dark, it was no longer sludgy. He does give references in the appendix to the use of an acetone soak.

   As far as the competition is concerned, the organization was the International Violin and Guitar Makers Association. You may be right about it being only a local contest, but an annual contest held but such an organization certainly sounds more extensive than that.

    Interestingly he did make a statement that hot hide glue would not stick well to rosewood, his preference was polyvinal glue. He did not advocate epoxy for rosewood either, but this was written in 1969 or thereabout and epoxy has surely changed since then.

     Art's book is nothing if not quirky, but he did inspire a number of folks who are now heavy hitters in the guitar business.

A friend brought back a number of billets of coco from guatamala and before I sliced them I did glue joint tests with TB 1, 2, 3 and west systems. No joint solvents. Each was clamped for 24 hours. All samples were the same size, 16 1/2 wide x 24 long. I supported them on their edges and hit the joint with a large deadblow hammer. All TB samples failed at glue joint. West systems did not fail, ultimately, the wood fibers to one side failed. Only west systems for me!

Dean

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Dean

I have made one cocbolo guitar and I glued the centre seam with gorilla glue and the braces with LMI white glue. The guitar is almost 2 years old and no problems yet. I did scrape with a freshly sharpened scraper both the spruce and the cocbolo just prior to glueing. Scraping or planing makes a much much better glue joint than sanding. I think the sanding may well imbed some of the oils in the pores with the sanding dust.

Hesh, I don't use it at all now as I started to get sensitive to the dust.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Great thread folks, thanks!

I glued a coco fretboard on neck using carpenter's glue and it seems to be holding up well but epoxy sounds safer, will remember that, thanks!

[QUOTE=Brock Poling] [QUOTE=JJ Donohue]Brock...what epoxy are you using on Cocobolo? Do you also use the acetone prep?[/QUOTE]

I am using West Systems 105 resin and 205 hardener.

[/QUOTE]

Brock, I was wondering what filler you used? 403? 406? I know in their owner's manual, they claim 403 to be the better all-round filler but then they claim that you should use a denser filler if you're gluing up hardwoods.

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