I Can't Believe This Happend AGAIN!

[tbz]

I talked to Spector and they said they have never seen this happen before and they have been building basses since the late 70's. My guess is that the weight of the bridge (it's solid brass and weighs a ton), the use of only 3 screws to hold it on and defective screws all contributed to the failure.

This is from your post back in April.

No one in the Spector club has ever seen this. Spector, as a company, has never seen this before either.

 

[jmlee]

If you still have the broken screws and any sort of magnifier, have a look at their cross-section and see if you see you can see what is shown in the images below. You may see it only on one or two of the screws. The series of lines show the progression of a fatigue crack in little jumps until final fracture occurs. The lines are often called "beach marks" because of their resemblance to what waves do on a beach. Screws which have loosened over time can go into bending when loaded as in a bass bridge. That could lead to a fatigue fracture in one screw, transferring load to the remaining screws, the process continuing until you see the apparently odd multiple fractures. [I'm a materials scientist with expertise in mechanics of materials...oh, and I play a little bass.]

.

 

[JoeWPgh]

So much wrong in here.

Screws can't break that far down if there is solid wood at the top of the hole.

The wood at the top is shot. OP didn't detect this on first repair.

The strings pull the bridge screws toward the neck. The screws move (bend) in the soft top of the holes creating a stress point where they broke. They broke at the point of anchorage: where solid wood began.

This has nothing to do with bridge design.....

...it has to do with whoever installed or re-installed the original screws at some point. THEY damaged the holes.

This is metal stress caused by the bending of the screws at half length and the continual stress working away at them for years and then again several months. True that the screws used by OP were probably junky.

This is what I suggested up thread. My suspicion for the original screws breaking is that they became loose over time. The tension of the strings pulled on them, distorting the upper part of the hole and bending, then snapping the screws. The replacement screws were spfter brass, so they suffered the same fate, only much faster. This isn't the only possible explanation, but for me, it's the most plausible

 

[aborgman]

In the original thread, several people called out the root problem, which is that brass screws just aren't strong enough for load bearing applications like this and will fail due to metal fatigue. Use steel screws. The sheet metal type like in 96tbird's picture are a good bet if you repair the holes. The holes were probably munged by the first episode, leading to the second failure as lethargytartare and fhm555 said. You should do something to fix that, whether it is installing dowel plugs or using inserts and machine screws, etc.

I'll argue that bridge screw shouldn't be bearing any load in shear - just like lug studs on a car wheel don't. The screws should be clamping the bridge to the body - and the friction between the bridge and the body should bear any shear load.

 

[40Hz]

I touched on this earlier. I hope the OP read your post because it is the only logical answer.

I noticed that. Which is why I reiterated and amplified your comment.

I think it's the only logical explanation too.

 

[JoeWPgh]

I'll argue that bridge screw shouldn't be bearing any load in shear - just like lug studs on a car wheel don't. The screws should be clamping the bridge to the body - and the friction between the bridge and the body should bear any shear load.

This is exactly right, UNTIL the screws become loose. Then they bear the entire load in shear.

 

[PortlandBass77]

See my post above, if this wasn't a troll comment. (Not saying it was, but....)

This was manufactured in the 80s by Kramer when they owned Spector. They really are not anything like a modern NS2, in terms of build quality, attention to detail, etc.

I thought it was Spector that owned Kramer? Anyways I guess that invalidates my comment? I've heard only good things until now about Kramer basses, maybe it's just this model that has this problem? Or maybe I need to test out more Kramers?

 

[leemelone]

So you repaired a broken instrument yourself, improperly and it broke again?

Shocking.

There's definitely some good advice here on how and why that repair would not take.

It is a bummer that you do not mention anywhere that Spector tried to help you with this off-warranty, but was not able to, as again, its 30 years old.

I personally would just take it to someone that knows how to fix it, and spend the $50 to prevent it from happening again.

Well that comment is pretty snarky. I've been working on my own basses for over 30 years and have never had to do a repair twice until now or pay someone else to fix my work. If you take the time to read every comment in this thread as I have, you'll see that there's some good information and a lot of wild speculation. And if you did read all my comments, you'll see that I actually did mention that Spector sent me some wrong size replacement screws but why let the facts interfere with a good snark?

 

[tbz]

Well that comment is pretty snarky. I've been working on my own basses for over 30 years and have never had to do a repair twice until now or pay someone else to fix my work. If you take the time to read every comment in this thread as I have, you'll see that there's some good information and a lot of wild speculation. And if you did read all my comments, you'll see that I actually did mention that Spector sent me some wrong size replacement screws but why let the facts interfere with a good snark?

Yeah, that materials scientist is clearly wildly speculating.

Clearly not user error.

Also, yes, outside of the OP you mentioned Spector helped you. You did not mention the warranty status, age of the bass, or anything else in the OP though, which is what 90% of the folks read.

It's a slam against a company that tried to help you, instead of a compliment that they've earned. This problem has nothing to do with Spector as a company, someone at Kramer made a bad call 30 years ago, and an improper response lead to this second problem.

Despite being over 20 years off warranty, they still tried to make up for a mistake they had no control over, simply because the bass has their brand name on it.

If you do not see the problem with the tone of your OP with all of that in mind, there's not much more that I can say, but god bless.

 

[tbz]

I thought it was Spector that owned Kramer? Anyways I guess that invalidates my comment? I've heard only good things until now about Kramer basses, maybe it's just this model that has this problem? Or maybe I need to test out more Kramers?

No, Kramer bought Spector in the mid 80s. Kramer went out of business in the 90s, Stuart Spector and company reclaimed the Spector name then.

Unless I'm completely mistaken this bass was built when Kramer wholly owned the Spector brand name.

Kramer, as of now, really has no affiliation with the original Kramer company outside of the name, and maybe an executive or two. So guitars or basses made by Kramer in the 80s would literally have no relation to any made now, outside of potentially shared model names. Different factories, different parts, etc.

As the OP mentioned in another thread Spector has never seen this issue before. No one in the Spector club has seen this issue before.

It's a pretty isolated incident and has no actual bearing on how Spectors are built now. Someone in the Kramer factor went cheap with screws in the 80s.....that just wouldn't happen with the modern Spector factory. Their current team is very small, hand builds everything and is incredibly competent and diligent.

 

[leemelone]

Yeah, that materials scientist is clearly wildly speculating.

Clearly not user error.

Also, yes, outside of the OP you mentioned Spector helped you. You did not mention the warranty status, age of the bass, or anything else in the OP though, which is what 90% of the folks read.

It's a slam against a company that tried to help you, instead of a compliment that they've earned. This problem has nothing to do with Spector as a company, someone at Kramer made a bad call 30 years ago, and an improper response lead to this second problem.

If you do not see the problem with that, there's not much more that I can say, but god bless.

You read things into my post that weren't there and weren't mentioned in the original post because they were irrelevant at that time. In any thread the OP can't think of every detail that may come up but I did address those as the thread progressed. That's how a conversation works. The fact about Spector sending me replacements came up, the age of the bass came up and because of that, any warranty talk was irrelevant. And I never once said anything bad about Spector or Kramer for that matter. If you think I did, then you're the one that can't see where the problem lies.

 

[tbz]

You read things into my post that weren't there and weren't mentioned in the original post because they were irrelevant at that time. In any thread the OP can't think of every detail that may come up but I did address those as the thread progressed. That's how a conversation works. The fact about Spector sending me replacements came up, the age of the bass came up and because of that, any warranty talk was irrelevant. And I never once said anything bad about Spector or Kramer for that matter. If you think I did, then you're the one that can't see where the problem lies.

If you do not see the problem with the tone of your OP with all of that in mind, there's not much more that I can say, but god bless.