Official Luthiers Forum!

Hi,

I joined the forum today and wanted to say hello.  Of course I will have a couple of questions about acoustic guitar building too.  I just finished by first (grand auditorium, black walnut, white spruce, and mac. ebony everywhere else).   If this seems familiar, I posted picks in January on the APM forum too. 

Could I ask for a suggestion to fill a crack in a back plate?   I bought a set of figured Oregon myrtle from Ebay which is supposed to be from one of the sponsors on this site.  The plates have matching 1" cracks in each back plate, across the grain.  Most of the crack will fall outside the guitar template at the waist, but I am concerned for when it comes time for routing the binding channel.  I am thinking of adding the backstripe between the plates to add a bit of width to avoid the cracks even more.   

Should I use white or cyanoac. glue with sawdust for the repair? I'm not sure which would be more appropriate for this application. 

Thanks,

Laurie

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Hi, Laurie, and welcome to the forum. We would love for you to post your pics here, too. You will get a lot of help soon, this group can fix anything. How big is the crack (width)? Something like hairline cracks can be fixed quite easily with CA. Just run a line of glue and let it soak in (under clamping pressure if it will close up). More experienced folks will be along shortly. Also, if the wood is indeed from one of our sponsors, and it isn't usable, I would recommend contacting them, and they will make it right, I'll bet. They are very, very service oriented.

Ron

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OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

Photos are a big plus when asking a question.

Welcome to the OLF.

Usually fine cracks are simply super glued with thin cyanoacrylate. It's just part of dealing with real wood. Can happen, especially if you let it dry out any below 45 percent RH.

We want to see the pics of your first guitar. Go ahead and make our day!

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Ron, you took the wordz right outta my mouth.....

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OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

you do not want to use yellow glue and sawdust it it's at all possible to avoid it. it is far too visible, especially under finish.

either ca or hhg and no sawdust is the glue of choice for crack repair on backs and sides whilst for tops hhg is preferred.

a photo and some explanation of what happens when you try to close the crack would help.

and welcome to the forum.

Hi Laurie, let me be the first Canuck to welcome you here.

You said the crack runs across the grain, this will most likely be noticeable even if repaired well. I would be temped to make a smaller guitar with this set of wood, rather than fixing a cross grain crack.

What guitar size were you planning on making with the Myrtle? Maybe a good excuse/reason for making a L-00 or something with a smaller bout.

Or is it possible to flip the plates end for end and get the crack outside of the body layout? Was the crack in the lower bout area? Flipping the boards would put it in the upper bout area and would most likely be eliminated.

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Welcome to the OLF
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[QUOTE=old man]Hi, Laurie, and welcome to the forum. We would love for you to post your pics here, too. You will get a lot of help soon, this group can fix anything. How big is the crack (width)? Something like hairline cracks can be fixed quite easily with CA. Just run a line of glue and let it soak in (under clamping pressure if it will close up). More experienced folks will be along shortly. Also, if the wood is indeed from one of our sponsors, and it isn't usable, I would recommend contacting them, and they will make it right, I'll bet. They are very, very service oriented.

Ron [/QUOTE]

Thanks - the Ebay listing said it came from Allied and I never thought to ask how it cracked.  I can't confirm with certainty where it came from, but its the nicest I think I have seen!   The width of the crack is a little under 1 mm and I haven't tried to close it yet (the pieces are unsanded and some cupping, so I didn't want to risk it). 

2 pics below.  Guitar pics to follow tomorrow...It's after midnight and I work in the morning!

Thanks,

Laurie

 

 

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Time you enjoy wasting is not wasted time.

[QUOTE=Rod True]Hi Laurie, let me be the first Canuck to welcome you here.

You said the crack runs across the grain, this will most likely be noticeable even if repaired well. I would be temped to make a smaller guitar with this set of wood, rather than fixing a cross grain crack.

What guitar size were you planning on making with the Myrtle? Maybe a good excuse/reason for making a L-00 or something with a smaller bout.

Or is it possible to flip the plates end for end and get the crack outside of the body layout? Was the crack in the lower bout area? Flipping the boards would put it in the upper bout area and would most likely be eliminated.[/QUOTE]

Thanks Rod - A smaller guitar is possible, but as a new builder, I was hoping to stick with the same shape while learning the ropes. I don't own anything but dreads and grand auditoriums, so I would need a tracing/plan/new mold as well.   The cracks either fall in the lower bout or at the waist, depending on the orientation.  I appreciate all the suggestions,

Laurie

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Time you enjoy wasting is not wasted time.

Laurie,

Welcome to OLF.  I'm a new member myself and this group is the best.

From looking at your pics of the crack, I would use CA as has already been suggested.  If the crack daylights out the edge in it's final shape, I would cut it to shape at that point, but leave the ends square.  This gives you a place to apply the clamps lenthwise when do the glue job.

Good luck, Doug 

I'm no expert at this, but seeing how small the crack is I think I would pack the hole with sawdust, spray the area with accellerator and then put a couple of drops of CA on it.  The accellerator should keep the CA from creeping too far into the surrounding wood to cause any problems when you put the finish on it.

 

God luck with it and welcome to the forum!

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Reguards,

Ken H

the ca won't be the problem, but the dust will probably stand out like a sore thumb.

you want to be able to close the crack and glue it so it is not visible, or as close to as you can.

let us know hat it does when you try to close it and we will have a better idea of what might work.

Laurie welcome to the OLF.
A couple of questions? Was the seller Allied or did the seller just list it as having come from Allied? Somehow I think it's the latter. Did the seller describe or have a picture of the crack in his or her listing?
From your picture it looks like a stress relief crack which can occur during the kiln drying process. I doubt very much that this can be clamped closed. I would suggest either filling with fine sawdust and CA or put this set aside until you are in a position to build a smaller bodied guitar.

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Hi Laurie,

Welcome to the OLF from yet another Canuck! As Bob has stated this is indeed a stress crack which occurred during drying, you typically see them around knot areas but they do occurr in spalted woods as well especially if the structure of the wood is in any stage of breaking down from the fungi that cause the spalt. For me....if I was going to use this piece I would first try for a smaller guitar to get outside the issue, second I would make a 3 piece back and add a nice piece of flame maple as the centre piece, I have some for just that purpose so you can contact me if you think that is a good option and third, if I was to fill that I would use epoxy and leave it clear. As has been said, on these light coloured woods anything you add is going to probably be darker than the wood itself and will be even more noticeable.

Good luck with it!

Shane

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Canada

[QUOTE=Bobc]Laurie welcome to the OLF.
A couple of questions? Was the seller Allied or did the seller just list it as having come from Allied? Somehow I think it's the latter. Did the seller describe or have a picture of the crack in his or her listing?
From your picture it looks like a stress relief crack which can occur during the kiln drying process. I doubt very much that this can be clamped closed. I would suggest either filling with fine sawdust and CA or put this set aside until you are in a position to build a smaller bodied guitar. [/QUOTE]

Hi Bob - the seller listed it as coming from Allied and there was a mention of a crack, but no picture.  I assumed it was with the grain...oops, I learned my lesson.  The set was a great price, so I'll start to look at some other body shapes to see what is feasible. 

Laurie

 

 

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Time you enjoy wasting is not wasted time.

Hi Laurie, and welcome. I have no advice that hasn't been given...but personally, I like your idea of adding a backstrip to help the crack fall outside the waist, if that's feasible.

Looking forward to your participation.

Bill

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Welcome!
Looking forward....

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Peter M.
Cornerstone Guitars
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