Double Bass Threads on "plate join separation"?

[eh_train]

Hi all,

A friend of a friend has a Romanian flatback bass where the two halves of the top plate are separating (approximately a 5" crack from the saddle heading "north" underneath the tailpiece). I know I'll need pics, but I've only seen a poor quality pic and don't have a copy as yet.

My first question is, can TBers point me in the direction of some previous threads on the subject? I've searched "plate" and "plate separation". There must be a better term to use. Any hints?

Thanks,

Paul (Eh_train)

 

[Mark Carlsen]

Center Seam

 

[eh_train]

Thanks Mark, I tried your suggestion. There are posts under 'center seam', but they all seem to be on the building process and wood selection. So far I haven't found posts on the post-build failure of this join.

I've seen a couple of other basses with this problem, and they seemed like potentially tricky situations. In both cases the seam was apart, with a gap, which suggested warpage (meaning the two pieces would need some convincing to go back to their "correct" position). So, if they're forced back together, you have unwanted stress on the wood, right?

I seem to recall TB discussion of this previously - any other links to old threads?!

Cheers,

Paul

 

[Matthew Tucker]

If the crack is a result of a glue-starved joint followed by a knock or something, the top needs to be unglued as far as the lower blocks, the crack re-glued, and the top re-attached with a dilute hide glue. it is possible to cleat the crack too in this way.

Now if the crack is due to shrinkage, it MAY be possible to do the above repair without a problem if the sides come together. However if the shrinkage is too great, a tapered splint may need to be glued into the crack. Under the tailpiece the repair will not be very visible.

It depends on the condition of the rest of the plate too ... if the wood is going to continue to shrink, the crack may continue to open unless the ribs are glued with a very dilute glue and allowed to pop from time to time.

 

[eh_train]

Thanks Matthew, that's a great help! I will try to see the instrument myself, and hopefully get some pics to post.

Cheers,

Paul

 

[robobass]

I have had center-seam separation problems on the back, but I've never heard of it happening on the top, and I imagine making a lasting repair is much more difficult. How old is the bass? I would consider this a defect in construction, and proceed based on this.