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HELP! soundboard cracked!

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Koendb
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Help! I was busy sanding my soundboard to thickness ( german spruce ) and I am to about 3.60 mm

I lifted the board to measure thickness at several spots, and suddenly I heard and felt a crack. The board cracked to halfway, parallel to the glueline ( about 2 ~ 5mm from the glue line )

Is this salvageable by glueing it back together?

It seems the crack is not completely through yet, so I could try to fill with titebond, or perhaps better with thin CA glue.

Or do I buy another set of spruce panels?

I aint touching this board for now and await your guys expertise...


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Boo
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@koendb I’m sorry I can’t offer up any help, other than moral support, it’s not my area of expertise. I feel that this is a mission for @markbailey should he choose to accept it (I know he will). 👍

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Bpower
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I would probably try and glue it with wood glue, put it back in the soundboard clamping jig for pressure, and then just consider that a second glue seam with some cleats on the inside to stretch across the joint. I'd be interested to hear what @markbailey would suggest on this one. 


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Koendb
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Posted by: @bpower

I would probably try and glue it with wood glue, put it back in the soundboard clamping jig for pressure, and then just consider that a second glue seam with some cleats on the inside to stretch across the joint.

@bpower That would be my first intuition as well, but I dont know if woodglue would penetrate enough in the crack. That's why my second thought was thin CA glue.

Posted by: @bpower

I'd be interested to hear what @markbailey would suggest on this one. 

Me too 😀

Posted by: @boo

I’m sorry I can’t offer up any help, other than moral support, it’s not my area of expertise.

@boo Thanks man , moral support is as important as technical support 🙂


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Rocknroller912
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@koendb

I would glue with Titebond and clamp like a normal joint but the longer you leave it the harder it will be for the edges to meet together. 
When you’re gluing the bracing I would fix it with the crack on the inside of the sound box so that the radius curve will push the edges together rather than force them apart. It also won’t be visible. 
I think Titebond is strong enough to hold without cleats but other people might disagree.

Some people call me a tool, others are less complimentary. Tools being useful things.


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Koendb
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Posted by: @rocknroller912

I would glue with Titebond and clamp like a normal joint

I have done this now.. I hope there is enough titebond in the split, we' ll just have to wait for now and see tomorrow..
What I have done is put a sheet of baking paper beteen the joining board and the soundboard , in the unlikely event that there is a part split all the way through and because that line does not match up with the center cutout for glue squeeze out. At least it wont be sticking to the joining board 🙂
Then I carefully put a ruler underneath the soundboard, next to the crackline, to force the split to open just a fraction ( I had to put some wooden clamps to make sure the line stayed open until I wanted it closed.

So then I used a fine painters brush and some tooth picks, put a bead of titebond over the crackline and gently rubbed allover the line with the toothpick and then went over it with the brush, dipping it like it was a suction cup. Hopefully that would be enough.
Then I used a damp rag to remove all excess glue.

Clamped everything down. I did not see any squeeze out afterwards, so I am a bit worried.


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Rocknroller912
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@koendb

Looks like you have it fixed ok. An alternative to cleats for cracks is very thin pieces of parchment which some violin suppliers sell. Unless you’re a vegan of course. It’s very strong and doesn’t dampen the soundboard as much. I also wonder if the crack is in an area which will be covered by the bridge plate and X bracing these will be strong reinforcement I think.

Some people call me a tool, others are less complimentary. Tools being useful things.


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Koendb
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Posted by: @rocknroller912

I also wonder if the crack is in an area which will be covered by the bridge plate and X bracing these will be strong reinforcement I think.

Well I still have a rectangular board, so I can still choose where and how it s going to end up. so I can definitely make sure that it has enough reinforcement.

I still have a lot of sanding to do though.. I am now between 3.50 and 3.70 mm, I just got rid of the sawing marks.
So I dont think I am anywhere close of making the braces yet.


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Koendb
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Success!!  The glue up seems to have worked perfectly

So today I continued and finished sanding. Here and there I am a little under 3.18mm ( or 0.125 "). Only a fraction though. So for a first attempt I think I should feel content.

 

Cut out the bodyshape with the bandsaw too.

IMG 20211219 145909268

That's enough stress for a weekend!


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Koendb
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I love how it looks now, if you hold it in front of a light source...

IMG 20211219 151605304
IMG 20211219 151613433

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Robin
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I love how it looks now, if you hold it in front of a light source...

Well done @koendb  , flawless.


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Rocknroller912
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@koendb

Top job invisible mending. A lot of the skill is learning how to fix mistakes as they happen, so it must have given you a big confidence boost.

Some people call me a tool, others are less complimentary. Tools being useful things.


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Bpower
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@koendb Fantastic. Good to hear everything worked out. Can't wait to see it progress. Good job. 🙂


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Russ
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Nice job fixing it @koendb

🙏🎶🎸🙂

🗝️ "Life's what you make it"🗝️


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Boo
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Posted by: @koendb

I love how it looks now, if you hold it in front of a light source...

@koendb Boom 💥 Looks great, well done. 👍

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mark bailey
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Great work folks - sorry I missed out on all the fun!

I was on the road and unable to comment but you guys got it sorted - AWESOME - that is what this place is all about ✊

 

 

Measure twice, cut once...


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Koendb
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Posted by: @rocknroller912

so it must have given you a big confidence boost.

@rocknroller912 You would think so, but quite the opposite actually, I am more afraid that it will desintegrate when I touch it!
I noticed, shortly after posting the latest updates, that a fine hairline crack again, formed, at the same place, but on the other side of the centre line.
Lucky it is still on what will become the innerside.

Could this be because I a have been sanding it in a cold, unacclimatized shed, then bring it back in a warm house to rest?
Or is this perhaps due to lesser quality wood?

So many questions.. so little experience with wood 🙂

Anyway I fixed that one as well, but I actually don't want to sand anymore, since I seem to have gone a bit too far with the sanding..
Some spots are 2.95~3.05 mm thick now. Is this still workable? I really feel like it can break at any point I am touching it. (I am not touching it anymore until I am ready to add the rosette and put the bracing in )


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Rocknroller912
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@koendb

If there is a crack on the opposite side same place then I guess it’s a fault in the wood due to drying and outside your control, but you are working with it so that’s good.

Some people call me a tool, others are less complimentary. Tools being useful things.


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Koendb
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Well that's it, I guess that board is ruined now, I made it worse I think, It now also cracked on both sides.
I  am going to order a new top and start all over, enough source for cleats material now. 🙄


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Rocknroller912
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@koendb

Dont give up yet most things can be fixed. Post some close up pics and get a few opinions.

Some people call me a tool, others are less complimentary. Tools being useful things.


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