Official Luthiers Forum!

Hi Kathy,
Long time reader of your inspirational site. Thanks for all the years of honest luthery.
Just my 2 cents, If you want to try mixing woods, I think I'd try a different set of woods (EIR and Mahogany perhaps)and try to use that beautiful blackwood for the sides.
I'd make an ebony block to match the part of your cutaway that's smunched up and let the sides into it. You'd have the ebony showing at the turn, but everyone (but us!) will think it's supposed to be there, and we won't tell anyone!
Since blackwood and ebony are related any humidity issues should be mitigated. Can't say that for dissimilar species.
vpelleri38894.8744907407

Thanks, Hesh
It's great to be here...

Would a coat or two of garnett shellac on the back bring it closer to the EIR sides as a color match?

I have to say thanks, too, for your site as an inspiration.
I hopefully will get from my present one finished acoustic to five by the end of the year, if all of the ongoing builds work out.

_________________
Jim Kirby
kirby@udel.edu

One other thought, Kathy,
Have you considered trying to put the smunched side into your cut-out form? Maybe you could complete the bend and then stabilize it with epoxy.
Art

Have you checked the color match wet? Seems like under a finish you're going to have a very noticeable difference, without a striking contrast that would make it look more intentional.

Don't know what other option would be better, but to my mind, EIR isn't the way to go.

Andrew

Kathy, one other thought. HAve you tried flattening out the broken side, then repairing the break prior to rebending? Easy to do with your slats and heat blanket.

Colin

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

Great idea Colin!

I just happen to check into this site and wandered into this discussion:
Colin, perhaps you can shed some light on/for me (again!): I have been working on a Braz RW B/S classical guitar: a few months ago, while bending the sides (on a bending machine) both sides developed cracks on the exactly same spot (in the upper bout.) I un-bent/flatten the upper bout parts, using bending iron; glued the cracked spots, about 1-1.5cm in width going across the grain on the outer edge using titebond, clamping them tightly. After drying, I soaked the flattened areas in hot/warm water, and put them back in the bender. The heat from the bender must have melted the glue; the cracks came back. Do you think I should have used a different glue? I am thinking about cutting out the cracked areas out and leaving them open; making semi-oval openings on each side, or taking another set of sides to mix/match.
Thank you.

Hi Kris

You need a different glue, many people use CA (Superglue) for this, I'm not a great fan of CA so I use a waterproof PVA.

Thank you, Russell:
I have 2 questions:
1. I actually thought about using CA, but was afraid that this would make the glued area too brittle. Is CA more or less brittle when dried vs. titebond, or does this matter at all?
2. After having bent and then flattened & re-bent what was already thin Brazilian sides; do you think this would be too much to try this again? Would this stress the wood too much? I had hand-planed the sides and they are slightly under 2mm thick. The back had a streak of resin(s) which cracked when I was testing the back-center jointing: I had put too much stress. It has been fixed, and it seems to be OK.
Thank you for your help.
Kris

Hi Kris

On question 1 I think CA would be fine many people use it sucessfully, personally I'm none too keen on the fumes in high doses, so avoid CA.

On the second question, you should be ok many vintage Brazilian Rosewood instruments have sides thinner than that and have stood up ok. RussellR38897.1562152778

Kris...BRW can sometimes crack for no reason, especially if it is thin. CA is a good way to go and when done can be indistinguishable.

I have built quite a few classicals that were mostly BRW and always had to deal with cracks at some point so I always had CA handy. I alwasy joked that at least that one stop would not come back with a crack.

Back when Martin was building alot of BRW guitars they would routinely flood the pieces with CA to stabilize if the pieces looked problematic. As the quality of BRW sets got much poorer they would also sometimes do things like use wood bleach on whole sets and then dye them for color as at least that way they had even coloring.