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Double Bass A crack that won't close

spaghettiwestern

spaghettiwestern

Mar 9, 2005
228
22
Greater Boston Area
#1
I'm working on an old Bohemian flatback bass that's suffered from the dry winter in my new apartment. Despite running humidifiers constantly, a nasty crack in the back has appeared.

The crack is in the upper bout, about 1/32-1/16 wide, about 8" long and goes all the way to the edge. I've tried opening the seam all along the bout in the hopes that this would relieve the tension and close the crack, but no dice. I can't budge it by pulling it together by hand, and long spool clamp across the back doesn't help either.

Any other suggestions for closing this puppy up?

I'd really like to avoid having to fill the crack with a sliver of maple and touch up, as this never really looks good.

Thanks much!

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#3
There is an old dowel plug in there (when I got the bass many years ago, there were brass brads all around the back, and the crack location certainly has something to do with this plug). Unfortunately, the plug isn't preventing the crack from closing. I can't even seem to bring the crack together enough for the plug to be a problem.
 
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#4
My main concern with this crack is that eventually the bass will need to have the top / back removed for a complete overhaul to correct about 100 + years of deferred maintenance - new back braces, clean up ugly old patches, etc etc. At that time, I'd like to be able to reverse this repair to see if I can get the crack to close on its own again. Trouble is, I don't have the time or space to do this now.

What's the current attitude toward filling cracks?

I'm thinking that if I can't close it otherwise, I may do a fill with a sliver of poplar, as described here:
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The compression method seems like it would preserve the edges of the crack well enough, so that if I were to steam it out later, the crack might still line up.
 
#5
Get that plug out of there, I'd guess it was put in to halt the small edge crack in lieu of purfling to halt edge damage. I'm certain its what created the issue. Then get the back off on both sides of the crack all the way to the upper corner and neck block. It could be twist or tension in the rib assembly. Sometimes even 100 years later these things don't want to go back to closed without force...and building tension (using force) in new or old, will just give you trouble down the line.
 
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#6
That crack has shrunk back and is full of dirt that will not close. Because there is no edge, you cannot take it loose there hoping to bring it together more. you will likely have to fill that area with new wood, but if it's not buzzing, might leave well enough alone until the back is off later
 
#7
Pull that plug out and shim it.
I bought a bass from an older guy who use to play with big bands.
It was full of cracks and wood filler putty.
Found a luthier and had him fix it. Shims were charged by the inch.
He did a nice job and the bass sounded better.
 
#8
MrLenny1 said:
Pull that plug out and shim it.
I bought a bass from an older guy who use to play with big bands.
It was full of cracks and wood filler putty.
Found a luthier and had him fix it. Shims were charged by the inch.
He did a nice job and the bass sounded better.
Click to expand...

Thanks folks. I let it lie for a bit to see what would happen when the humidity came back. Not much movement, so I'm thinking the shim approach is the way to go. I'll post pics when the deed is done.
 

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