Problem with home-made box - warbling/distorting sound - Forums

Hi all,

I finished my first build with a home-made box a few weeks ago, and have been enjoying it immensely. I made the box from 1/8" spruce for the soundboard and 1/4" spruce for the back and sides, all solid wood.

I recently took the guitar over to a friend's house and unfortunately the gig bag fell over... When I arrived the guitar had lost much of its tone and volume, and was making a strange warbling sound which got worse with light pressure on the soundboard.

I noticed later that the lid was coming away on one of the corners (I had glued the lid down with superglue). I thought this might have been the cause of the problem, so I cut the soundboard off with a knife and re-glued with wood glue, and gave it a full 24 hours under clamps to set.

After re-stringing the guitar, there was an improvement, but the sound is still nowhere near as crisp as before, almost distorted and there is still a slight warbling at times.

I believe this may be a problem with the bracing inside the box, which looks like this:

These are excess strips of spruce which I just glued in place - does this look sufficient to keep the soundboard stiff enough?

I guess the next step will be to try to remove the soundboard again, but I'm thinking this will be a lot tougher with the wood glue - any tips there?

Anyway, any input or advice would be gratefully received.

Cheers all!

Rick

Replies

Richey Kay November 9, 2013 at 1:30am

OK - update... I've managed to cut the soundboard off with no damage to either part using only a small craft knife and some skill.

Now where's my superglue?

(KIDDING)

I'll let you know how the re-bracing goes. Thanks all!
Richey Kay November 8, 2013 at 11:19am

Thanks for the feedback guys! So:

Bottom is also wood glued, will probably be even harder to get off...

The battens look odd because I needed to allow for the neck to run under the soundboard. I haven't yet attempted a bolt on neck as I think I might require mucking about with truss rods etc which seems a bit excessive for a 3 stringer.(correct me if I'm wrong).

I'm thinking that as everything was fine before, Ron's suggestion that one or both of the battens are loose seems likely. When I get some more spruce I'll make a new lid in case I can't get it off in one piece.
- Bad Finger (Eric) > Richey Kay November 8, 2013 at 11:43am
  
  That guitar is a beauty. Too bad it is making itself a challenge for you. You might consider just taking the braces out. The way you have them is light and weak where they should be strong and strongest where they can be light and weak.
  
  Is there a chance the string tension is pressing the bridge down enough that the sound board is making partial contact with the neck? Too bad your sound holes aren't big enough to give you a view or reach inside.
  - Richey Kay > Bad Finger (Eric) November 8, 2013 at 11:54am
    
    Thanks Eric - I was enjoying playing it until these problems reared their head! All part of becoming a better builder I suppose :-) roll on number 9!
    One thing I should make clear is that the battens were originally glued in with CA (due to my impatience) so I would be keen to try again and use maybe 3 or 4 struts rather than 2, and obviously use a more impact resistant adhesive...
    I've had a look at the surface of the soundboard but it doesn't seem to be dipping at all... seems almost as stiff as a standard ply CB lid to the touch.
    - robert jones > Richey Kay November 8, 2013 at 2:09pm
      
      Well I would still take off the bottom, shouldn't be any more difficult to remove than the top and a simpler piece to replicate if necessary.
Randy S. Bretz November 8, 2013 at 6:40am

Id say for getting the soundboard off, I`d go with a dremel and some cut off wheels. I have the dremel mini wood saw disc, it`s a beast to use but does a great job like this. Table saw wood work to, drop the blade down real low. Butt the box bottom against the fence
- Richey Kay > Randy S. Bretz November 8, 2013 at 12:00pm
  
  Hmmm... I have some of those dremel wood discs but I don't have anything like that much of a steady hand with it!
Richey Kay November 8, 2013 at 5:51am

Certainly seems that way Ron... I'll take this as a learning experience ad I would prefer that my builds can take a bit of a knock!
Any ideas on how to get the glued soundboard off?
- Ron "Oily" Sprague > Richey Kay November 8, 2013 at 9:07am
  
  Learning experience, indeed. My first two homemade boxes were glued AND screwed; really tightened them up. But then had to build a hinged top for one, and learned from THAT, that a screwed but not glued bottom was a better solution, for electronics access. It's all about building the next one, hehe.
  
  Agree with the others: your batten profiles are inverted from what a normal brace would look like: tall in the middle, tapered to almost nothing at the ends, standing on edge. Look inside a commercial acoustic...
- robert jones > Richey Kay November 8, 2013 at 6:45am
  
  Take the bottom off.
  
  Remove the battens and replace with ones turned on edge and glued with wood glue. Look into an acoustic to get an idea of the batten profile.
  
  As your top is glued on with wood glue any attempt to spread loose corner joints enough to re-glue is likely to cause damage. You could wrap the corners with screwed on angle metal to keep them firmly together, small brass hinges could also work.

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