Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
I Can't Believe This Happend AGAIN!
- Thread starter leemelone
- Start date
- Status
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 am going to guess that the bridge is not sitting flush with the body, judging by the way the breaks look and by the different lengths of the broken screws. You should check this first, and, if you can, make sure the bridge is not tilted to one side or the other by using calipers. If the joint between the bridge and body is not perfect and flat, the screws will break. In addition, it could affect the sound by not fully transmitting the vibrations of the strings to the body.
One way of doing that is to coat the underside of the bridge with ink, like from a felt tip pen, then screw it down to the body, then remove it. This will show you the contacting surfaces, but, of course, it will stain the area underneath the bridge. There may be other ways of doing this, but you get the idea.
But you should solve the root problem, before going out and getting new screws. I would replace the wood screws with a countersunk threaded in sockets and machine screws
One way of doing that is to coat the underside of the bridge with ink, like from a felt tip pen, then screw it down to the body, then remove it. This will show you the contacting surfaces, but, of course, it will stain the area underneath the bridge. There may be other ways of doing this, but you get the idea.
But you should solve the root problem, before going out and getting new screws. I would replace the wood screws with a countersunk threaded in sockets and machine screws
Here'a my guess at what's happened:
During the 25 years of the original screws, which were gold plated steel, they became loose. This allowed the string tension to pull on them and ream the upper part of the screw hole larger. This, combined with age, created a fail point on the screws, as the tension could now eventually bend, and then snap them. You replaced the originals with brass screws, which is a much softer metal. The upper parts of the screw holes were still too large, so the same thing happened again. Only this time it happened much faster due to the softer metal of the brass screws. I would drill and dowel the screw holes, and then use gold plated steel screws
During the 25 years of the original screws, which were gold plated steel, they became loose. This allowed the string tension to pull on them and ream the upper part of the screw hole larger. This, combined with age, created a fail point on the screws, as the tension could now eventually bend, and then snap them. You replaced the originals with brass screws, which is a much softer metal. The upper parts of the screw holes were still too large, so the same thing happened again. Only this time it happened much faster due to the softer metal of the brass screws. I would drill and dowel the screw holes, and then use gold plated steel screws
Hope you fix that, but…
That's what I like about stringing through body : no tension stress on your bridge screws...
That's what I like about stringing through body : no tension stress on your bridge screws...
Maybe some odd chemical reaction causing a metal embrittlement?
when the bass is tuned (assuming standard), are they tuned to an odd frequency? If your tuner is set to 443hz, for instance, you might be adding undue tension...still, nothing the screws shouldn't be able to handle.
That's all I've got... other than that, I agree, it's "hainted"
when the bass is tuned (assuming standard), are they tuned to an odd frequency? If your tuner is set to 443hz, for instance, you might be adding undue tension...still, nothing the screws shouldn't be able to handle.
That's all I've got... other than that, I agree, it's "hainted"
Last edited:
Here is my take. You are simply tightening the screws to much causing them to twist and break. Nothing mysterious going on here.
Never seen anything similar to this....
Anyway...longer bolder stainless steel screws of the better quality.
I don't know the spector bridge, but i would drill additional holes if possible, let's say 2-3 more, and probably be set. A total of 5-6 quality steel screws usually do not break, under any condition
Anyway...longer bolder stainless steel screws of the better quality.
I don't know the spector bridge, but i would drill additional holes if possible, let's say 2-3 more, and probably be set. A total of 5-6 quality steel screws usually do not break, under any condition
I think it might be the situation where the screws are breaking when they're being installed. Possibly from over tightening. That leaves only the top few screw threads, rather than the entire screw, holding the bridge in place. You'll run into that in furniture making sometimes. Especially when using long joining screws or when installing hinges. There's a dense spot somewhere in the wood (most often tight grain or a hidden knot, or occasionally even an epoxy or other glue line) that the tip of the screw penetrates but grabs onto very firmly. If you tighten the screw too much once it hits that spot, it will still rotate (because the metal still has some give) and give the impression you're still tightening it, but it will actually snap somewhere along the thread length and leave you with only a quarter or a third worth of screw actually holding things in place.
Since that bass has a paint finish, there's no way to look at the wood itself and see if the above applies.
FWIW, when inserting screws into wood, the general rule is to screw it in until it's seated - then give it an extra quarter turn at most and stop. When removing a properly installed wood screw you should feel resistance, then a slight crack when it first starts to rotate, but come out fairly smoothly after that. If it's extremely tight all the way out, the screw was most likely installed improperly - or the wrong size/type of screw was used.
I still don't know why the so-called quality guitar manufacturers still use wood screws when a ferrule and bolt combo should be the norm by now for anything (e.g. necks, bridges, control plates, etc.) that needs to be removed from time to time. Wood screws are primarily designed to be inserted once and left alone. Bless all those little cost-cutting measures that characterize manufacturing these days...
Since that bass has a paint finish, there's no way to look at the wood itself and see if the above applies.
FWIW, when inserting screws into wood, the general rule is to screw it in until it's seated - then give it an extra quarter turn at most and stop. When removing a properly installed wood screw you should feel resistance, then a slight crack when it first starts to rotate, but come out fairly smoothly after that. If it's extremely tight all the way out, the screw was most likely installed improperly - or the wrong size/type of screw was used.
I still don't know why the so-called quality guitar manufacturers still use wood screws when a ferrule and bolt combo should be the norm by now for anything (e.g. necks, bridges, control plates, etc.) that needs to be removed from time to time. Wood screws are primarily designed to be inserted once and left alone. Bless all those little cost-cutting measures that characterize manufacturing these days...
Last edited:
This and stainless steel oval head screws. Once dowelled, you can re-drill with the proper pilot hole size and you should never have to worry about it again.
- Jun 3, 2009
- 3,330
- 398
- Disclosures
- Bassgearu, Music Industry Consulting and Sales. Tech 21, NBE Corp, Sonosphere.
Honestly, there has to be too much string tension. Either the strings are too thick a guage or they are over tightened. I have basses that are older then me with the original screws and bridge on them, never had this happen, ever. You really have to be putting a ton of tension on the bridge especially if new screws broke too.
That is my take.
That is my take.
The original screws are counter sunk flat head and an oval head would interfere with movement of the saddles.
Last edited:
I agree that the screws were likely screwed into less than ideal holes... fill the holes and get better screws.
Another thing to try, that at least will eliminate the bridge as a culprit is to run a Qtip through the bridge mounting holes and see if the Qtip grabs any burrs in and around the holes. Likely not the culprit, but an easy to do check to ensure that it's not the bridge holes cutting the screws.
Fishheadjoe
Another thing to try, that at least will eliminate the bridge as a culprit is to run a Qtip through the bridge mounting holes and see if the Qtip grabs any burrs in and around the holes. Likely not the culprit, but an easy to do check to ensure that it's not the bridge holes cutting the screws.
Fishheadjoe
It would be fun if people read the replies before replying...
The problem's pretty much been sorted and the solutions revealed.
The problem's pretty much been sorted and the solutions revealed.
The partially-stripped-hole theory is probably the right one, but I had another thought. Brass contracts and expands with temperature change more than most metals--is it possible the bass has been in an environment where it is experiencing different or wider temperature changes? Maybe the brass bridge is expanding and contracting just enough to put force on the screws and shear them off?
- Status
