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| cracked brazilizn back set http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=5291 |
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| Author: | PaddyD [ Fri Feb 24, 2006 9:55 am ] |
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agggggggggggggggghhhhhhhhhhhhhhh, agggggggghhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh!!!!! help me, what is the best way to fix cracks in brazilian back sets (yes sets  ) i have about 4 in which cracks have appeared, and i would quite like to try and save them!!
paddy |
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| Author: | Don Williams [ Fri Feb 24, 2006 10:18 am ] |
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Fortunately, I have extensive experience in fixing BRW cracks. Send them to me and I'll fix them for you. |
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| Author: | Don Williams [ Fri Feb 24, 2006 10:21 am ] |
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Ok, in case you suspect I would have kept those backs, I'll just tell you what to do. Provided these are just hairline fractures, and not opening up, you can wick in water-thin CA glue (cyanoacrylate). I have found that it helps to place the wood on wax paper, and then flood the whole are with ca to get any micro-cracks filled also. You can get the glue to activate by wiping it off with a papertowel. Not sure why that works, but for some reason it does... |
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| Author: | PaddyD [ Fri Feb 24, 2006 10:21 am ] |
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ok sure, whats your address??? how long will it take? |
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| Author: | PaddyD [ Fri Feb 24, 2006 10:22 am ] |
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| Author: | PaddyD [ Fri Feb 24, 2006 10:23 am ] |
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hairlines are not such a problem for me, these are starting to open up?? |
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| Author: | Don Williams [ Fri Feb 24, 2006 10:29 am ] |
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Ouch...Opening eh? That could be problematic. I would almost yield to the experience of others on this one... I can fix the hairline cracks, but when they open... Well, they may be drying out too much for starters. How is your humidity? |
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| Author: | PaddyD [ Fri Feb 24, 2006 10:57 am ] |
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all sets stored in humidity controlled room, 42-45% |
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| Author: | Don Williams [ Fri Feb 24, 2006 11:09 am ] |
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Hmmm... this may be a case of internal stresses being released. When were these cut? Recently? Nice stash of wood you have there! ! ! |
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| Author: | PaddyD [ Fri Feb 24, 2006 11:29 am ] |
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they were cut from some very old billets.... about 100years old, i believe, i will have to have a think on this one |
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| Author: | Shane Neifer [ Fri Feb 24, 2006 12:28 pm ] |
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Just try gel CA, if they are larger then I would use epoxy. Glue it all from the back. I would use clear packing tape over the crack on the front and flood from the back. When drypeel the tape off, if some sticks with the glue just sand it off. Good luck, I sure hope you get them fixed!! Shane |
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| Author: | Robbie O'Brien [ Fri Feb 24, 2006 1:52 pm ] |
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Are the backs already glued on the rims or not? Are they quartersawn? Can you clamp them so the cracks disappear? If you can then some higher gram weight hide glue should do the trick. If they are quartersawn you may be able to cut them apart and reglue them. Another option ,depending on how dark they are, is to use a thin BRW or other rosewood veneer to fill the void and then use the CA or hide glue method to glue it. If they are lighter in color then some dye and a little art work will hide the problem. |
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| Author: | Serge Poirier [ Fri Feb 24, 2006 2:02 pm ] |
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Paddy, if you look into what Robbie said and go for the hide glue with higher gram weight, i'd suggest you buy it from Lee Valley tools, theirs is 260g compared to 192g that the majority uses. I use it and it is very strong, it it's any help Serge |
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| Author: | crowduck [ Fri Feb 24, 2006 2:14 pm ] |
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PaddyD, Can you post some pictures? That would help alot. |
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| Author: | PaddyD [ Fri Feb 24, 2006 7:32 pm ] |
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i'll post pics later, last day of the deer hunting season on monday, so i need to get some meat!!! |
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| Author: | Shawn [ Fri Feb 24, 2006 8:38 pm ] |
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I build classicals and use more BRW than any other wood. Brazilian Rosewood while haveing a wonderful tone can sometimes crack if you look at it the wrong way  .
If it is just starting to open and is not a big gap the best thing to do is to apply a clamp to help close the crack but leave it snug not tight. You do not want to cause the wood to deflect, just help to close the crack so that when you wick in the CA that it will not have an unseamly crack. If you do this (mostly closing the crack) it will be very close to indistinguishable. Additionally if you see any hairline cracks that have not opened it is a good idea to stop additional cracking by applying some CA to that crack. I do the above before I thickness the plates and afterwards it is difficult to find any deflects. For tight cracks I use CA whereas for loose knots, voids and other imperfections where filling is needed I use epoxy with or without sawdust to match. I have used hide glue as others have mentioned but more often than not will fill cracks with CA as I never have the hide glue heated up and ready when I am looking for cracks as it is before I begin any other part of assembly. For tops that I am repairing I only use hide glue as it gives the most unseen glue line. Someone mentioned in the past on another thread but for a small batch of higher strength hide glue you can use unflavored gelatin which is about twice as strong as 192 hide glue. |
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