Double Bass bass bar question

[DaveCottrell]

If the ends of the bass bar come loose, has the top moved or has the bar moved?

One end has previously been glued, the other end (near the tailpiece) is about 1/2 away from the top and there are cracks under and next to it.

This is a Christopher bass that has given me fits ever since new (seams constantly opening, cracks in top, it seems there is a ton of stress in it.) I think they used green wood to make it. It belongs to a middle school and I really don't want to tell them to scrap it, but I don't want to tell them that it will always be in the shop.

Right now it is on my bench being reassembled with realigned joints and fresh glue but I need to address the bass bar situation next.

 

[KUNGfuSHERIFF]

Run your hand over the belly around the ends of the bar. If it’s out of round, you’ll know.

It’s possible the bar is sprung (fitted under tension, like a longbow) but that practice fell out of favor many years ago. It seems more likely that the wood wasn’t aged properly.

A lot of us would cut 4” squares of linen or denim, lay them over the ends of the bar after it’s been glued back down, and saturate the patches with hide glue. It won’t move any more.

 

[RSBBass]

It is also possible that it took a blow to the top.

 

[dperrott]

Both ends are off? Could try to push the bar up with a post and glue it that way then linen it. Sometimes that works. If its a ply there is a way to glue the bar down with out taking the top off but that doesn't work for the upper part since the fingerboard is in the way.

 

[james condino]

It seems like I used to spend more time fussing about with half-@$$ ship in a bottle style approaches than it actually takes me to remove a top, do a proper repair, and then glue the top back on.

 

[byacey]

It sounds like the bar was sprung when made new. I would just make a new bar for it. Chalk fit it so it glues in without any tension, and it'll be good for a long while.