Double Bass Advice re top repairs

[eh_train]

Lovely! A thin breast patch might be the thing to do - give it some structural integrity and help the tone too.

How thick is the top in/close to the centre?

Hey Jake,

The top is 3/8", or 9.75 mm thick, between the bridge feet.
When you say a thin breast patch, do you mean to remove material and patch, or just add material? Also, should it be something like a large oval that would cross both the centre line and the soundpost crack?

Thanks for clarifying,

Paul

 

[Turnaround]

I use alcohol on hide glue but we were talking about white/yellow glue, ergo the white vinegar. Cider vinegar might have a slightly higher concentration of acetic acid but it also has colour, which would keep me from using it. That and its more expensive...

Thanks Jake. Good to know the "why".

 

[360guy]

I recall that Jim Ham told me he adds a 5" disc of maple to his tops (even in new construction) as it helps with the overall sound. I did that, using 2mm thick maple. I don't have a before/after comparison because the bass was in disrepair when I bought it, but I really like the tone now that it's all done. Try to center it in line with the sound post spot.

 

[360guy]

http://photobucket.com/soundpostpatch

 

[Jake deVilliers]

Hey Jake,

The top is 3/8", or 9.75 mm thick, between the bridge feet.
When you say a thin breast patch, do you mean to remove material and patch, or just add material? Also, should it be something like a large oval that would cross both the centre line and the soundpost crack?

Thanks for clarifying,

Paul

Yeah, I was thinking of a biggish oval that would encompass that whole region and tie it all together structurally and sonically.

It would be easiest to simply add an extra 1/8" or 3/16" to the thickness of the top. That thickness would taper to nothing in a few inches, so its not likely to have a detrimental effect on the tone - probably the opposite.

Its a judgement call though, and I don't know what the bass sounded like before or what it sounds/smells/feels like now. Going by the way the top came apart, I'd say go ahead and add to it, but you're the guy on the ground.

 

[Jake deVilliers]

Thanks Jake. Good to know the "why".

And it would be distracting to have your bass wafting French fry odours out the f-holes!

 

[arnoldschnitzer]

Your top is already quite thick, so I'd be reluctant to add mass. I can't tell from the pics, but I seem to see a dent from the post and no cracking. I assume there is a crack there? If so, the correct fix is an inlayed patch. If you are only trying to remove the dents, you can steam them out. Good luck...

 

[eh_train]

Hi all,

Thanks for the input...

Your top is already quite thick, so I'd be reluctant to add mass.

The top might be thick, but it has been through some abuse and shows some slight signs of wavering. I am reluctant to put it back together without any reinforcement.

I can't tell from the pics, but I seem to see a dent from the post and no cracking. I assume there is a crack there? If so, the correct fix is an inlayed patch.

There definitely was a crack, which I've reglued. I think I will go with the inlaid soundpost patch and then a minor reinforcing patch around the belly.

Good luck...

Thanks!

Paul