Double Bass End pin bang

[Dave Craig]

Hi all,

My son was practising his 1/2 size bass this morning, when suddenly I heard a loud bang. Attached is the photo of what happened... The end pin is now at a slight angle, and as well as the wood around the end pin being stoved in there's a large crack where the back of the bass should be joined at the bottom. A few questions for you:

1. The bass has probably had several owners, and is almost certainly not that great quality, so what should I do? It was great value when we bought it 3 years ago (<£200), and it was a functioning bass that he could have at home to practise on.
2. There are a couple of holes in the wood near the pin which makes me think that it's been altered before. Would those have been for a different end pin configuration?
3. Is it likely to have been a setup issue, or could a fairly small teenager easily do this much damage to a bass - is there something that he shouldn't be doing e.g. holding it at too much of an angle? Obviously if we get it fixed or replace it I don't want similar to happen...

Thanks for your advice.

Dave.

 

[Neil Pye]

Hi Dave. Its not a setup issue, that's for sure. It looks to me like the bottom block glue joint has failed, so the load from the strings has gone into the ribs directly round the endpin. The glue failure could be the result of an impact on the endpin at some stage. Its likely to be an expensive repair. Might be worth thinking about getting something better. Where are you based? Renting might be a better option for you

 

[Dave Craig]

It looks to me like the bottom block glue joint has failed, so the load from the strings has gone into the ribs directly round the endpin.

That makes sense, thanks. I did wonder if the small holes originally had bolts to help hold the bottom block in place. Although the bass doesn't leave the house much, it did go to a music weekend in a van a month or so ago with some other basses and one of the others was apparently wrecked beyond repair. There's a good chance it got a knock and then the unusually hot weather has just pushed it over the edge - it doesn't normally go above 20 in our house...

Might be worth thinking about getting something better. Where are you based? Renting might be a better option for you

We're near Glasgow.

Thanks for taking the time to help, much appreciated.

Dave

 

[Neil Pye]

My brother lives in Ayr and knows most of the string dealers cos his daughter studies at the RCS. I'll ask him if he know where to rent locally

 

[robobass]

Yes, it looks like the bottom block came loose from the ribs once before, and those holes were for screws used to clamp it back in place. Since it's a very low value instrument, the same repair might be attempted again, but with more screws. Doing it properly, i.e. removing the top or back, is almost certainly out of the question. But, if you can find a repairer who is willing to do meatball work, which is what is called for here, then a repair is possible.

 

[Dave Craig]

Yes, it looks like the bottom block came loose from the ribs once before, and those holes were for screws used to clamp it back in place.

I just took a closer look, and I can just make out a brass philips screw head in one of the holes about 6mm deep. It may be that they used to be flush on top and just got pulled through, though I think I would have noticed them. My bodge would have been less aesthetic, but having a piece of external wood and some washers would probably have worked better.
Thanks for the suggestion of how to attempt a fix, I'll ask around.

 

[robobass]

Ah. So the bottom block (the piece of wood which holds the bottom ribs together and supports the endpin socket) was probably already loose when you got the bass. You might attempt this repair yourself. If you can get those screws out, what you need to do is remove the socket, and see if it's feasible to get some slow setting epoxy well into the gap between the block and the ribs. Next, yes, use screws and external wood to pull the block back to the ribs. Wax it or put cling wrap on it so it can be removed after the epoxy sets. No need to leave it there. The epoxy is what will provide strength. Screws won't do much, as you have already observed. Another common approach is to put a big bolt through the socket hole, with big washers or blocks on each end. I would leave this alone, however, since it's tricky to get a nut and washers inside the bass and tighten, and also you want to have the hole clear so that you can wipe away the splooge. Good Luck!

 

[turf3]

Ah. So the bottom block (the piece of wood which holds the bottom ribs together and supports the endpin socket) was probably already loose when you got the bass. You might attempt this repair yourself. If you can get those screws out, what you need to do is remove the socket, and see if it's feasible to get some slow setting epoxy well into the gap between the block and the ribs. Next, yes, use screws and external wood to pull the block back to the ribs. Wax it or put cling wrap on it so it can be removed after the epoxy sets. No need to leave it there. The epoxy is what will provide strength. Screws won't do much, as you have already observed. Another common approach is to put a big bolt through the socket hole, with big washers or blocks on each end. I would leave this alone, however, since it's tricky to get a nut and washers inside the bass and tighten, and also you want to have the hole clear so that you can wipe away the splooge. Good Luck!

It seems to me that you could modify the above slightly by using a couple of screws on either side of the end pin hole to pull the block back into position, but use long machine screws with big washers under the heads, and "blind fasteners" so you have a nut on the far side rather than using wood screws. There are a wide variety of blind fasteners available: "rivnuts"; toggle bolts; expanding fasteners, etc. McMaster-Carr will have a wide selection. Then you can just leave the long machine screws in place as a belt-and-suspenders operation.

 

[Dave Craig]

Thanks for all of the suggestions. I think they are at an appropriate level for a. the instrument, and b. my bodging skills... I've got an endoscope type camera which I will stick down inside the bass tonight to see if I can find out anything else about what's going on. Then I'll come up with a plan of attack.

 

[robobass]

It seems to me that you could modify the above slightly by using a couple of screws on either side of the end pin hole to pull the block back into position, but use long machine screws with big washers under the heads, and "blind fasteners" so you have a nut on the far side rather than using wood screws. There are a wide variety of blind fasteners available: "rivnuts"; toggle bolts; expanding fasteners, etc. McMaster-Carr will have a wide selection. Then you can just leave the long machine screws in place as a belt-and-suspenders operation.

Maybe, but I think if you pre-drill pilot holes, then wood screws would work well enough, and you wouldn't need to fuss with fastening nuts from the inside.

 

[turf3]

Maybe, but I think if you pre-drill pilot holes, then wood screws would work well enough, and you wouldn't need to fuss with fastening nuts from the inside.

No, what I'm saying is that if you use blind fasteners you don't need to fasten the nut on the inside.

 

[robobass]

Ah. I didn't understand. You want to insert the fasteners from the outside. I still think that wood screws would be simpler, easier, and at least as effective.

 

[turf3]

You may well be right.

 

[ctrlzjones]

I had a similar situation and was lucky to glue the tail block back in place with a guerilla procedure with the help of these pieces. The thingie with the strings attached goes inside through the f.hole and is screwed to its counterpart on the outside after injecting not too much hide glue. If you want to make it look more professional just substitute the recycled cables with a nice looking kind of wire, any precious material will do.

Not that I am very proud about having it done that way, but it saved €1500 for taking the top off and it's still holding up 1 year later and, thinking about drilling screws into a double bass, seems to be a less violent procedure.

 

[robobass]

Yes, I remember you posting this. Nice work.

 

[ctrlzjones]

Yes, I remember you posting this. Nice work.

Well, even if it still holds together I would hesitate to call it "nice work". Me too prefers doing things the good way. Only this time the cost for a proper repair were en par with the instruments value. So the DIY-guerilla act seemed the way to go.

 

[Dave Craig]

Thanks again for all the advice - the bass is back in operational order. I managed to get the original screws out and re-adhere the block to the wood. Because the block was only partially detached, it was hard to get much glue in there, but because there were already holes, I used some more screws, with some brass plate acting as a large washer to further strengthen it. It won't be winning any beauty prizes but it should last. Cheers.