What caused this crack?

[Jacy]

What generally causes a crack like this? It was sitting in my room not being touched and then SNAP. it goes directly from the endpin hole almost all the way up the lower bout. Needless to say, I was pretty distraught.

Some say it may be dry weather, some say stress in the wood, but i can't really find a solution that seems to fit. any ideas? There's a small crack on the opposite side of the endpin that has been there since I bought the bass about 3 years ago. It hasn't moved at, but now i'm worried I should have something done to it.

My first post here, an it's with a busted bass!

[Roger Mouton]

Just a guess but could the big crack on the one side of the end pin have started from the smaller, pre-existing crack on the opposite side? Perhaps related to a cracked end block?

[doktorfeelgood]

Very dry weather....bad glue joint? Do you run a humidifier in your house in the winter when the heat is on? You should if you don't. Not saying that was the culprit but could have been a contribuing factor. Extremely dry air can cause all sorts of problems with musical instruments. )-(

[reedo35]

ouch! Possibly a cracked block, but more likely The endpin hole was too tight and it shrunk slightly, causing stress in the area that cracked.My other guess, assuming it's a relatively new bass, is that the ribs started reshaping and the top and back did'nt.

[ctregan]

Dry climates, wood shrinks.

[Eric Swanson]

Originally Posted by Jacy

...but i can't really find a solution that seems to fit. any ideas?

+1 on the hygrometer/humidifier. The reasons for the failure may be myriad and complementary, but at this point, ruminating on them may be burning daylight. At this point, IMHO, the relevant action is to get it fixed,ASAP.

Don't polish the bass or fondle the crack. Don't try to glue it yourself. Keep it clean and untouched.

Get the bass to a luthier, pronto. If you fill out your profile, folks here can help you with more geographically-specific resources...

[arnoldschnitzer]

The rib dried and shrunk across its width. Because it could not move at the blocks, it cracked, relieving the stress.

[1st Bass]

Originally Posted by arnoldschnitzer

The rib dried and shrunk across its width. Because it could not move at the blocks, it cracked, relieving the stress.

And the correct fix? Is there more than one proper repair? How would you approach this, Arnold? I haven't ever come up against anything quite that severe, so I'm seizing this as a learning opportunity, if that's OK.

Chet Bishop

[arnoldschnitzer]

The rib needs to be slipped loose from the tailblock, then the crack extended to the seam. The rib should be heated by the block so it shrinks like the rest of the rib, then left to acclimate for a few days. Then the crack should be glued back together, reinforced, and finally re-attached to the tailblock. The tailblock/top glue surface will then need to be trimmed. The alternative is to insert a veneer into the crack, glue it up and reinforce while leaving the rib attached to the block. Unless the crack closes with minimal pressure, it should not be fixed without taking the top off the bass.

[1st Bass]

Thanks! I would not have thought of the warming and drying (acclimating) step. I'm really glad I asked. :-)