Old & abused double bass reconstruction (as opposed to restoration). Help appreciated

[Beedster]

Folks

 

An old double bass requiring some serious repair has come into my possession; in fact it would me more correct to say a collection of parts that all belonged to the same instrument have come into my possession. My aim is to rebuild the instrument to the degree that it's playable and structurally sound, as opposed to restoring it to its original state.   

 

These books, as well as the expertise of this forum, will be my guides

 

 

 

It's a 4/4 with a 43.5 speaking length. It has a break at the scroll (which is only held on by the tuners), the endpin gets no traction with the body, there is no nut and the tailwire appears to be made out of a piece of old fence. However a good look around the inside of the body suggests no cracks, no loose bars and - perhaps miraculously- the sound-post is still in place and appears to be quite stable.

 

The main challenge at present relates to the neck, which is not attached to the body, has a considerable amount of glue residue and splintering, and also a curious shape. Going on the obvious signs of previous alignment between neck and body the piece of wood that appear extended sits inside the back of the instrument, that is inside the body. 

 

 

 

 

 

Ultimately I'm not sure what purpose that V-shaped gap serves and whether is is something to retain or fill. Thanks in anticipation of any help you can offer?

 

Here's some pics of the business end of the body

 

 

 

 

And finally a photo of the neck almost in place

 

Edited January 27 by Beedster

[JPJ]

Calling @Blartfactor10 - clean up aisle 9 

[pete.young]

This looks similar to my old Musima, it looks like someone has attempted a not-very-good repair using PVA, which has splintered the wood off the side of the neck and stuck it into the socket, and possibly also stuck some of the socket onto the neck sides.  I took the Musima to a local luthier and he came up with 3 options.

 

Option 1 was so expensive he didn't bother writing it down! I think this was a non-screw option, which may also have involved making a new neck.

 

Option 2 aka bodge was to clean off the PVA, leave the splintered wood in place and attempt to glue the neck back in place hoping it would still fit reasonably tightly. And then drill the heel and fit 2 long screws through the heel and into the body block, which would provide pretty much all of the strength.

 

Option 3 was to remove all the splintered wood from neck and socket, clean out all the damage and PVA, glue a thin veneer to the sides of the socket and maple facings to the sides of the neck, and glue it back together. Then fit screws as for option 2, which would be a backup rather than the primary source of strength in the joint.

 

For me, none of these options made economic sense given the value of the bass.

 

No idea why there's a 90 degree notch. It looks as though it was done at the time of the previous repair. In the bottom picture you can see an extension of the saw cuts. the only thing I can think of is that the original cap was part of the back, and it splintered off when the original failure happened.

[Burns-bass]

30 minutes ago, pete.young said:

This looks similar to my old Musima, it looks like someone has attempted a not-very-good repair using PVA, which has splintered the wood off the side of the neck and stuck it into the socket, and possibly also stuck some of the socket onto the neck sides.  I took the Musima to a local luthier and he came up with 3 options.

 

Option 1 was so expensive he didn't bother writing it down! I think this was a non-screw option, which may also have involved making a new neck.

 

Option 2 aka bodge was to clean off the PVA, leave the splintered wood in place and attempt to glue the neck back in place hoping it would still fit reasonably tightly. And then drill the heel and fit 2 long screws through the heel and into the body block, which would provide pretty much all of the strength.

 

Option 3 was to remove all the splintered wood from neck and socket, clean out all the damage and PVA, glue a thin veneer to the sides of the socket and maple facings to the sides of the neck, and glue it back together. Then fit screws as for option 2, which would be a backup rather than the primary source of strength in the joint.

 

For me, none of these options made economic sense given the value of the bass.

 

No idea why there's a 90 degree notch. It looks as though it was done at the time of the previous repair. In the bottom picture you can see an extension of the saw cuts. the only thing I can think of is that the original cap was part of the back, and it splintered off when the original failure happened.

 

I've seen about three "Option 2" repairs (and owned one of them). If the purpose of this is to save a vauable instrument, it's a bad idea. If it's going to save it from being scrapped, it's worth it. 

 

I reckon if you cleaned of the PVA from both the neck and inside the cavity, it would (with a little gentle persuasion) slot straight in there. Guess you have to be careful about the height and the angle, but assume you'll be cutting a new bridge in any case.

 

This demands a comprehensive photo diary!

[Beedster]

14 minutes ago, pete.young said:

This looks similar to my old Musima, it looks like someone has attempted a not-very-good repair using PVA, which has splintered the wood off the side of the neck and stuck it into the socket, and possibly also stuck some of the socket onto the neck sides.  I took the Musima to a local luthier and he came up with 3 options.

 

Option 1 was so expensive he didn't bother writing it down! I think this was a non-screw option, which may also have involved making a new neck.

 

Option 2 aka bodge was to clean off the PVA, leave the splintered wood in place and attempt to glue the neck back in place hoping it would still fit reasonably tightly. And then drill the heel and fit 2 long screws through the heel and into the body block, which would provide pretty much all of the strength.

 

Option 3 was to remove all the splintered wood from neck and socket, clean out all the damage and PVA, glue a thin veneer to the sides of the socket and maple facings to the sides of the neck, and glue it back together. Then fit screws as for option 2, which would be a backup rather than the primary source of strength in the joint.

 

For me, none of these options made economic sense given the value of the bass.

 

No idea why there's a 90 degree notch. It looks as though it was done at the time of the previous repair. In the bottom picture you can see an extension of the saw cuts. the only thing I can think of is that the original cap was part of the back, and it splintered off when the original failure happened.

 

Many thanks Pete, yes it's clearly suffered a poor repair, and the more I look at it the more I suspect the repair was an attempted modification, perhaps to reset the neck angle or height. I can't escape the feeling that what I'm going to call the wing - the protruding piece of wood near the cap - has been glued on to the cap where it has been cut away (the lines are too clean for it to have been a break) from the back of the bass. So, if this is the case reversing this modification as far as possible might be the best path. I'm going to do some fine measuring and drawings on Saturday to see how it might all work out.

 

 

 

I suspect that whatever path I opt for there's going to need to be some screws or bolts involved, unless I'm very lucky. Chuck Traeger will of course be displeased, but all going well it'll be playable and stable  

 

But in the meantime I'd welcome the thoughts and advice of people who actually know what they're doing 👍

[JoeEvans]

I think I'd be inclined to clean out the socket on the body and get it to as smooth and flat a finish as possible on all faces, even if that means making the socket a mm or two bigger all round. Then trim back the neck on all the areas that will contact the body, again aiming for smooth, flat mating surfaces, even though the block will end up a few mm small. Then glue veneer of appropriate thickness onto the mating surfaces on the neck, to leave it a few mm too fat in all dimensions. Glue on the veneer so that the grain runs the same way as in the neck. Then you can plane or sand back the neck block until you get a perfect fit with the socket. I would personally use an epoxy glue to fit the veneers to the neck, for maximum strength, then a conventional hide glue when you fit the neck back to the body. You'd need to get all the PVA off to get good adhesion for hide glue.

I wouldn't bother with screws myself. A good glue job is much stronger and if the glue job isn't good you're doomed in the long run anyway. 

I'd glue a bit in to fill the v-shaped gap.

[Beedster]

Thanks @JoeEvans 👍

 

I'm reading on Talkbass that white vinegar can be used to remove the glue residue, any thoughts on the credibility of this and the potential to damage the wood? 

[Beedster]

12 hours ago, Burns-bass said:

 

I've seen about three "Option 2" repairs (and owned one of them). If the purpose of this is to save a vauable instrument, it's a bad idea. If it's going to save it from being scrapped, it's worth it. 

 

I reckon if you cleaned of the PVA from both the neck and inside the cavity, it would (with a little gentle persuasion) slot straight in there. Guess you have to be careful about the height and the angle, but assume you'll be cutting a new bridge in any case.

 

This demands a comprehensive photo diary!

 

Thanks Lawrie, this is very much save it from the skip. @pete.young's Option 2 was what I was initially considering but it looks like I'm not dealing with a broken instrument but a poorly repaired one, which leads me to worry that even if the neck and body will fit back together nicely around the glue and splinters - which is a big if as it looks like the two have been apart for some time - it's probably going to be neither stable in the long term or positioned correctly. So yes, as you suggest, clean up the PVA, see how things stand before potentially doing further woodwork. And yes this will almost certainly need a new bridge although the original one is hanging around somewhere 👍 

[Beedster]

13 hours ago, pete.young said:

This looks similar to my old Musima, it looks like someone has attempted a not-very-good repair using PVA, which has splintered the wood off the side of the neck and stuck it into the socket, and possibly also stuck some of the socket onto the neck sides.  I took the Musima to a local luthier and he came up with 3 options.

 

Option 1 was so expensive he didn't bother writing it down! I think this was a non-screw option, which may also have involved making a new neck.

 

Option 2 aka bodge was to clean off the PVA, leave the splintered wood in place and attempt to glue the neck back in place hoping it would still fit reasonably tightly. And then drill the heel and fit 2 long screws through the heel and into the body block, which would provide pretty much all of the strength.

 

Option 3 was to remove all the splintered wood from neck and socket, clean out all the damage and PVA, glue a thin veneer to the sides of the socket and maple facings to the sides of the neck, and glue it back together. Then fit screws as for option 2, which would be a backup rather than the primary source of strength in the joint.

 

For me, none of these options made economic sense given the value of the bass.

 

No idea why there's a 90 degree notch. It looks as though it was done at the time of the previous repair. In the bottom picture you can see an extension of the saw cuts. the only thing I can think of is that the original cap was part of the back, and it splintered off when the original failure happened.

 

Thanks Pete that's very helpful. I've considered all the options in question and a new neck is one of them, in part because the original has three issues, a broken scroll, the heel, and a very worn fingerboard. I'm going to see how it goes with the original in the meantime 👍 

 

The notch is a mystery  

[JoeEvans]

1 hour ago, Beedster said:

Thanks @JoeEvans 👍

 

I'm reading on Talkbass that white vinegar can be used to remove the glue residue, any thoughts on the credibility of this and the potential to damage the wood? 

I've never tried that - it doesn't sound especially likely but worth a go! 

I think I'd be working with a wide, very sharp chisel and a piece of plywood, cut to the right size and chamfered at the edges, with sandpaper wrapped around it.

[Beedster]

16 minutes ago, JoeEvans said:

I've never tried that - it doesn't sound especially likely but worth a go! 

I think I'd be working with a wide, very sharp chisel and a piece of plywood, cut to the right size and chamfered at the edges, with sandpaper wrapped around it.

 

That's my thinking, but I'm guessing a chemical appraoch would not only be less work but potentially a whole lot cleaner. I'll do some investigating and report back 👍

[Beer of the Bass]

White vinegar does soften PVA type glues more effectively than water alone, I tried it in a guitar repair. Though that was more at the stage of encouraging the joint to let go in the first place than cleaning up the residue, which still needed to be scraped.

[Beedster]

13 minutes ago, Beer of the Bass said:

White vinegar does soften PVA type glues more effectively than water alone, I tried it in a guitar repair. Though that was more at the stage of encouraging the joint to let go in the first place than cleaning up the residue, which still needed to be scraped.

Thanks @Beer of the Bass, that resonates with what I've read over on TB, it turns solid and stubbon pockets of glue into something like sticky plasticine that then needs to be removed quite carefully. I have just acquired some wihite vinegar and, just in case, some white wine vinegar    

[Owen]

I have nothing useful to add, but admire your have-a-go attitude!

[Owen]

If we are going to become emotionally invested in this we will need pictures of the body as well.

[Beedster]

2 minutes ago, Owen said:

If we are going to become emotionally invested in this we will need pictures of the body as well.

Tomorrow I will reveal all Owen 👍

[Owen]

3 minutes ago, Beedster said:

Tomorrow I will reveal all Owen 👍

Not all the scenarios that could refer to are attractive.

[Beedster]

7 minutes ago, Owen said:

Not all the scenarios that could refer to are attractive.

Harsh 😆

[Owen]

But fair.

[Owen]

Yeah, that was last week.....

[SubsonicSimpleton]

Removable neck conversion worth considering?

 

[Beedster]

On 15/01/2024 at 17:05, Owen said:

Yeah, that was last week.....

 

Sorry I will post some pics Owen, crazy hectic week so far  

[Beedster]

3 hours ago, SubsonicSimpleton said:

Removable neck conversion worth considering?

 

 

I was thinking that, and in fact this instrument would be an ideal candidate...

 

But, i used to own a Chadwick folding bass. It is a very well designed, beautifully engineered, and functionally elegant solution to a a problem I don't have. I suspect I might be better served by simply taking an old German instrument and making it playable, giggable, and who knows even recordable, rather than trying to imitate Chadwick and in doing so turning a potentially nice bass into firewood  

[Owen]

18 minutes ago, Beedster said:

 

Sorry I will post some pics Owen, crazy hectic week so far  

That sucks

[Beedster]

So, this bass..............

 

Is not going to be as straight forward as I'd hoped 

 

Firstly the PVA in the neck pocket is stubborn

 

 

Although having said that, repeated and patient reapplication of white vinegar is slowly getting through the PVA on the heel

 

 

But, not only is the fingerboard slightly detached from the neck

 

 

But there's a crack in the neck itself

 

 

But the body itself is in great condition, and looks wonderful so worth persisting

 

 

This is going to be a lovely instrument again 👍