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How To Safely Remove Broken Bridge Screws?
- Thread starter leemelone
- Start date
I just wanted to update everyone who took the time offer their help and knowledge. I was able to fix it myself with just a hand drill and new screws. Because the screws were soft brass and broken in half, I was able to use a slightly smaller bit and drill them out without removing much wood. The trick is going very slowly, don't apply pressure and just let the bit do the work. I took my time and did it in several short sessions. That way I was able to keep my hand steady and not round out the holes. I bought some new #8 x 1 inch brass screws at Home Depot for a couple of bucks. They work perfectly and tightened down nicely by hand. It's as good as new and there's no damage whatsoever.
Wow, I'm surprised and impressed that worked! I would have bet that the drill would walk off the screw into the wood. Nice. Now, I'd strongly suggest you replace the brass screws with stainless steel ones because they're much, much stronger.
I think it was because the screws were broken off about a 1/4 inch below the body that it was easier to control. That and the fact that I ran the drill very slowly and let the bit do the work. As far as the screws go, Spector is sending me some steel ones free of charge. :0
This kind of fatigue failure in metal typically happens in something that is cyclically stressed. A tiny crack initiates at a stress concentration (like where the threads start), and everytime the fastener is stressed or subject to bending, the crack propagates a little more. Finally one day the remaining metal isn't strong enough to hold the tension and blammo! Probably all the screws were mostly cracked through and when the first one failed, the increased tension on the others broke them.
What is weird, of course, is that this doesn't happen very often, because screws in instruments don't get cycled as often as say a car or bike part, and usually aren't running close to their max strength. I would check to make sure the bridge is fitting the body absolutely flat, just in case it was rocking slightly when tension on the strings was brought up and that was bending the screws a little. And use steel screws, but you have that covered.
What is weird, of course, is that this doesn't happen very often, because screws in instruments don't get cycled as often as say a car or bike part, and usually aren't running close to their max strength. I would check to make sure the bridge is fitting the body absolutely flat, just in case it was rocking slightly when tension on the strings was brought up and that was bending the screws a little. And use steel screws, but you have that covered.
That's great to hear! Good job with the questions and the patience/ tenacity to carry it thru.
Even if galvanic action was a factor, using steel or s/s screws will eliminate that in the future.
Even if galvanic action was a factor, using steel or s/s screws will eliminate that in the future.
Not necessarily. My experience with stainless fasteners becoming stuck in aluminum is they almost always failed at the root of the threaded portion, and if you look at the pic that is where all three of those failed. The head and shank would be effected, but the failure was usually at the same place, even if that part of the fastener was deep in the threaded portion of the hole it was in. that said, I tend to agree it was metal fatigue due to long term stress, but it's still odd as all heck.
Never seen that! Thanks for responding. Doesn't seem logical, but it's a data point.
There is very little logic involved when dealing with metals in a coastal environment where salt crust is deposited by the morning dew and temps and humidity tend to hang in the 80's and 90's most of the time. We recovered an outboard that had come off a transom and laid on the bottom for 4 days and it was eaten beyond any practical use. There were some salvageable parts, but enough of it was so aggressively attacked by corrosion it was cheaper to just replace it. It was also where I learned the solids in WD40 are hygroscopic. Many a well meaning boater ruined their steering cables by lubing them with WD40. Once the liquid evaporated, the remaining solids would suck up that salt rich moisture from the air and corrode them up tighter than dick's hat band. We used a ZEP product named Master Mechanic for our GP lube/cleaning spray and it worked a treat.
Wow, another really helpful bit of info! Thanks!
WD-40 is a very misunderstood and widely misused product. It was developed to displace moisture, and that's what it should primarily be used for.
WD-40 is a very misunderstood and widely misused product. It was developed to displace moisture, and that's what it should primarily be used for.
Glad you took care of it yourself leemelone. It's always personally satisfying to overcome a problem on your own.
Most welcome Pilgrim. WIfey says I'm a warehouse of worthless information. It's nice to occasionally have something useful to add.
Most welcome Pilgrim. WIfey says I'm a warehouse of worthless information. It's nice to occasionally have something useful to add.
thirded, steel screws of some kind at least; brass screws are way too weak.
also +1 more to this being a crazy thing i've never seen before.
One more note about screws: The best screws to use are Sheet Metal Screws, rather than Wood Screws. They are available in the same sizes; that is, you can get them in #8 x 1" flat head Phillips. The advantage is that Sheet Metal Screws are made from steel and are hardened, because they are made to be driven through sheet metal. Most Wood Screws, like the ones that you bought, are just unhardened mild steel, probably 1018.
The Sheet Metal Screws are much stronger, less likely to snap off, and less likely to strip out the heads. Also, their threads are sharper and a narrower "v", so they will dig deeper into the wood without as much pressure to split it. I use Sheet Metal Screws for everything on instruments where I'm fastening things to wood: Neck screws, strap button screws, pickguard screws, and especially the teeny little tuner screws. I recommend that you never use the little screws that come with tuners. Throw them away and use the same size Sheet Metal Screws. You will save yourself much grief.
By the way, stainless steel Wood Screws aren't really any stronger or harder than normal plated steel Wood Screws. They are normally made from 18-8 stainless, which is just a soft mild stainless, about like 1018 mild steel. I don't know why people think that stainless steel is so much stronger than mild steel. Some of the special alloys are, but not the alloys used normal parts.
The Sheet Metal Screws are much stronger, less likely to snap off, and less likely to strip out the heads. Also, their threads are sharper and a narrower "v", so they will dig deeper into the wood without as much pressure to split it. I use Sheet Metal Screws for everything on instruments where I'm fastening things to wood: Neck screws, strap button screws, pickguard screws, and especially the teeny little tuner screws. I recommend that you never use the little screws that come with tuners. Throw them away and use the same size Sheet Metal Screws. You will save yourself much grief.
By the way, stainless steel Wood Screws aren't really any stronger or harder than normal plated steel Wood Screws. They are normally made from 18-8 stainless, which is just a soft mild stainless, about like 1018 mild steel. I don't know why people think that stainless steel is so much stronger than mild steel. Some of the special alloys are, but not the alloys used normal parts.
IMHO, Because chromed wood screws aren't common in the hardware store and stainless look better than cheap coated (zinc) mild steel wood screws.
If you do use zinc plated steel screws, you can easily buff up the heads. The zinc plating is tough, and it's naturally a satin silver color. But, if you hold it against a buffing wheel with tripoli compound it will shine right up and look almost identical to chrome. Besides being much more expensive, chrome plated screws aren't that tough. The chrome plating is thick enough that it often chips off, particularly in the Phillips head. Ordinary zinc-plated Sheet Metal Screws with the heads buffed up are the strongest "chrome" screws you can get. And they are inexpensive and commonly available. You just have to take a few seconds each to buff the heads.
With all that said, I use stainless Sheet Metal Screws on my own model basses, just because I prefer the more subtle shine of the stainless.
With all that said, I use stainless Sheet Metal Screws on my own model basses, just because I prefer the more subtle shine of the stainless.
Been using Sheet Metal screws for a while, especially for mounting bridges- they can be purchased from a fastener house, and sometimes thru auto parts stores, tho the ones from some auto parts stores are now of questionable quality. The automotive sheet metal screws usually have a much more durable finish, even the black ones.
Actually the issue is stainless stronger than brass screws which caused the original problem. Chrome plated steel does look best but is VERY hard to find in screws. So my choice is typically stainless steel screws. It can help if you use a buffing wheel on an Dremel or take them to a real buffing wheel and polish the visible heads up nice. The color will be slightly off from chrome plating, but still will look pretty nice.
Also I second the vote for stainless flathead sheet metal screws or even plated ones. They have deeper sharper threads than wood screws and will grip wood nicer and won't strip out the holes as readily. However if you REALLY want to fix it RIGHT I'd suggest installing threaded inserts and using SS flathead socket head cap screws to hold the bridge down. Yes, overkill but I've modded all my G&L L2500 bridges this way. The G&L bridges only use TWO screws to hold them down and there are nightmare photos on the net of them pulling out (not just dropping off!) The threaded inserts and cap screws eliminate the need to do the "screws in the through-body string holes" mod or stringing through body. The downside of this fix is that if you have a vintage bass, keeping it as original as possible is important. If it were me, due the vintage nature, I'd just go with SS sheet metal screws. I'd only go inserts if you had needed to drill out some of the wood. But that's the options.
Finding the right screws can be a hassle because few hardware stores have the kinds of things you are looking for. There are places online that have all kinds of screws (even some chrome plated ones) but you may have to buy a box of them. Still usually not THAT expensive compared to a full luthier professional fix.
