Snapped off screw heads, removing the rest of the screw from the hole??

Busker · #1 09-08-2007, 07:18 PM

I just picked up an old S.D. Curlee Curbeck bass for pretty cheap. It has some problems though.

One problem is that 3 out of 5 screws that hold the bridge to the body have broken, and I guess I did this when I removed the bridge (I had to get the strings and neck pickup out of the way to get to the truss rod nut and I figured removing the bridge with the strings still on it was the quick & easy way to do that). Part of these screws remain in the hole and I need to get them backed out. Any tips on how to do this?

The other problem is the neck. Sighting down the neck resembled a ski jump - so much so I was worried that the truss rod was broken. It seems the truss rod is not broken however, and maybe the rod had no tension on it at all when I bought it. I removed the nut and tightened it up somewhat just to test it. Whether or not it'll do it's job under string tension remains to be seen.

I did plug it into an amp. Whoa! Those are "patent applied for" Dimarzio P style pickups and they have a lot of output.

Son of Magni · #2 09-08-2007, 08:07 PM

What, you unscrewed the bridge from the body with the strings still on? Get your hands away from those tools!

bopeuph · #3 09-08-2007, 08:20 PM

I've been seeing this tool bit on TV commercials lately that you can use to get them out. Maybe look into that.

Nick

Busker · #4 09-08-2007, 08:22 PM

The strings were loosened before I loosened the bridge.:/

The screws probably snapped because they are soft brass and had been embedded in the hard wood for nearly 30 years. Why they would have used brass is beyond me.

meev992 · #5 09-08-2007, 08:26 PM

it takes 5 minutes to make a baby and 18 years to get rid of it.

DONE

hope that makes sense

meev992 · #6 09-08-2007, 08:28 PM

Quote:

Originally Posted by bopeuph

I've been seeing this tool bit on TV commercials lately that you can use to get them out. Maybe look into that.

Nick

that's similar to what auto-technicians do, to remove stripped lug-nuts on a wheel. They bore out whatever is stuck and then re-thread.

theshadow2001 · #7 09-08-2007, 08:29 PM

There are some tools you can get(screw extractors). I don't know too much about them. But you basically drill into the screw that's sheered. Then hammer this tool into the hole. It has a reverse thread on it. You use the tool to turn the damaged screw, the more you turn it the more the reverse thread bites into the hole and the stronger it grips it, so the whole systems basically works to get the screw out. Their probably expensive things though. Another thing is they are probably smallish diameter wood screws that you have broken that would require a small hole to be drilled, which could be tricky as small drill bits can break quite easily. Then getting the right sized tool might be tricky. You never know though your local hardware store might have everything you need.

Busker · #8 09-08-2007, 08:30 PM

Quote:

Originally Posted by meev992

it takes 5 minutes to make a baby and 18 years to get rid of it.

DONE

hope that makes sense

No, it doesn't make sense at all.

Some of you "luthier types" sure are snooty.

Son of Magni · #9 09-08-2007, 09:04 PM

Quote:

Originally Posted by Busker

...Some of you "luthier types" sure are snooty.

Yeah, that may be...

Screw extractors are very hard to use for screws that size, especially if they're soft like brass (or hard). The extractor will tend to expand the screw making it stick more as you try to extract it.

I would consider looking at the settings of the intonation and decide if you can drill new holes ahead or behind the old holes, and still have enough range of adjustment for the intonation. So just remount the bridge 1/8 inch off from where it was with new holes and screws.

Busker · #10 09-08-2007, 09:16 PM

Quote:

Originally Posted by Son of Magni

Yeah, that may be...

Screw extractors are very hard to use for screws that size, especially if they're soft like brass (or hard). The extractor will tend to expand the screw making it stick more as you try to extract it.

I would consider looking at the settings of the intonation and decide if you can drill new holes ahead or behind the old holes, and still have enough range of adjustment for the intonation. So just remount the bridge 1/8 inch off from where it was with new holes and screws.

I could easily reposition the bridge as there is plenty of leeway on the saddle adjustment, but I don't want to. Only as a last resort would I do that.

The original bridge screws are small, short and brass.

Why S.D. Curlee thought these were a good choice I don't know (they might have been supplied with the Badass bridge though). The bass was built in '79, the days of brass guitar parts. They used as much brass on the bass as possible. Brass nut, brass control plate cover, huge brass neck plate, brass screws. What hardware that isn't brass is gold-plated to match the brass. They liked that look I guess.

I could probably drill the broken screw ends out carefully, then put slightly longer steel screws in for plenty of hold and bite.

DigthemLows · #11 09-10-2007, 10:52 AM

Find a bit that is exactly the same size and bore the screw out of there. Then mix up some epoxy and wood dust and fill in the hole. Start over with a new screw. I did this on a bridge screw that snapped while I was tightening it and it's good as new.

Mon Rominee · #12 09-10-2007, 11:08 AM

I would follow Digthemlows' advice, but personally, I'd substitute dowel plugs for epoxy & wood dust. Just use patience, because boring out that screw will heat it up tremendously, and you do NOT want the heat to fracture or compromise the body wood in any way.

DigthemLows · #13 09-10-2007, 02:00 PM

Quote:

Originally Posted by Mon Rominee

I would follow Digthemlows' advice, but personally, I'd substitute dowel plugs for epoxy & wood dust. Just use patience, because boring out that screw will heat it up tremendously, and you do NOT want the heat to fracture or compromise the body wood in any way.

I agree! I didn't have dowels around so I went the harder way. And yeah, watch the heat!

Bryan316 · #14 09-10-2007, 02:44 PM

God allmighty, you really did a number on this bass!

Okay. Do you have access to a very sturdy drill press? Either tabletop or standing?

If so, go buy an endmill. 2-flute self-plunging. It is NOT a drill bit that will take the path of least resistance and walk away from the screw. Order up one that's maybe 1/8" or 1/16" diameter.

Clamp the body of the bass lightly to the drill press' table. Align the endmill as closely centered to the screw as you can, then clamp the body down supertight. PROTECT THE BODY! Don't clamp directly to the body, you'll destroy the finish!!!

Use the endmill to cut away the metal of the screw and the surrounding threaded wood.

Then once all the screws are cut clear, get hardwood dowels the same diameter of the endmill you used, and glue them into your new holes. Once the glue is fully cured, you can rescrew the bridge back in the same place.

Son of Magni · #15 09-10-2007, 02:45 PM

Quote:

Originally Posted by Mon Rominee

I would follow Digthemlows' advice, but personally, I'd substitute dowel plugs for epoxy & wood dust. Just use patience, because boring out that screw will heat it up tremendously, and you do NOT want the heat to fracture or compromise the body wood in any way.

I'd be careful what you use dowels for. This would mean your screws will go into end grain. What you really want is to use a plug cutter to make plugs with the grain going sideways.

Wood Ascention · #16 09-10-2007, 02:49 PM

The best thing to do is use two plug cutters one two remove the screw and a small amount of the wood around it, second to cut a face grain plug the diameter of your new hole and glue it in there flush off with a knife or chisel and voila. The problem with using a dowel is that you will be screwing into end grain which is very poor at holding screws and strips easily. I've been using this trick for years for those damn brass screws. Works like a charm. If your using a hand drill go very slow until the cutter is started, they like to walk, or better yet if possible use a drill press.

Good luck to ya.

Bryan316 · #17 09-10-2007, 03:01 PM

Yeah plug cutters also kick butt, although they're sometimes hard to come by the right diameter you need.

Busker · #18 09-10-2007, 05:59 PM

Quote:

Originally Posted by Bryan316

God allmighty, you really did a number on this bass!

Come on now. How was I supposed to know that simply removing the bridge would cause this to happen? If I would have known, I would have taken the stings off the tuning peg posts instead.

Still, the screws are not supposed to snap off like that. I was using normal pressure on the screwdriver. It's the manufacturer's fault, really, for not thinking about the consequences of using smallish soft brass screws in hardwood. Maybe Fender uses steel screws to hold down the bridge for good reason. Never sheared off one of those.

Besides, the way S.D. Curlees were built, you have to remove the bridge and pickups if you ever need to unbolt the neck, since it has a long tang that goes most of the length of the body (the neck also has brass screws,

but they are large and probably won't shear like that).

I'm not taking off the neck anyway, but I'm just sayin'. It was an earthquake, a flood, a volcano eruption, it rained frogs. IT'S NOT MY FAULT!

Mon Rominee · #19 09-10-2007, 07:45 PM

Yes, plugs would be perfect, but that is another investment in tooling, versus readily available materials (dowels) that I've used a ton of times and have yet to have anything strip out.

I'm not negating sage advise, but if it was between nothing and dowels, I'd chose dowels.

I always put a couple drops of white glue in the freshly re-drilled holes in the dowels to stabilize the wood being threaded, if that helps put minds at ease (I'm just ribbing ya)

Have a woodworkin pal cut you some plugs. AND, if you're gonna spin an endmill to clear out the remaining screw bits, make sure your drill can spin real fast, or it won't be worth a damn.

PJaye · #20 09-10-2007, 08:15 PM

If you're handy with a Dremel, you can use a small burr to gently grind away the wood AROUND the broken screw. After that, use a pin vise with the correct diameter collet and tighten the pin vise around the screw securely and back the screw out. Do this ONLY if the bridge will cover the recessed areas around the screw when you're done. You can also use small vise grips if no pin vise is available.

Using an EZ-Out (screw extractor) is the cleanest approach though. The smallest screw size you could do is a #8. You'd use a trade size #1 EZ-Out with a 5/64" (.078) drill bit. A Dremel tool again comes in handy to flatten the top of the screw so that you can center the drill properly. You only get one shot at drilling, so it helps to make a dimple in the center of the screw with an awl to locate the center first.

When it comes to working around delicate finishes like guitars, it's best to use a slow speed (hand drill) when drilling the hole for the extractor, making sure the drill is kept plumb to the guitar body at all times. Drill to a depth of about 1/8 in.Hope it works out.