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Problem re-attaching broken ground wire

Postby Will_m » Tue Jul 05, 2011 4:30 pm

Hi all, the ground wire on my fender jaguar baritone has snapped off and I'm having trouble getting it back on as its snapped off one of the bridge posts. Does anyone have any idea how I can get the bridge post out or suggest another place to attach the ground to?

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Re: Problem re-attaching broken ground wire

Postby zenguitar » Tue Jul 05, 2011 5:29 pm

That's bad news will_m,

this is one of the nastiest jobs you can find on a guitar. And because yours has stud mounted bridge and saddle, there's no alternative location for the string ground. The bushing is a tight friction fit into a slightly undersize hole in the body.

Essentially, you have to pull the bushing out of the body, feed a fresh length of insulated cable through so that the stripped end is poking into the bushing hole. Then refit the bushing.

The potential problems are damaging the finish when pulling the bushing and refitting it, and making the hole oversized when you are working on it.

There is a specialist tool for removing the bushing, but I know of no one in the UK who carries it. The StewMac Knob and Bushing Puller is ideal. But expensive; £27.90 isn't too bad for a specialist tool but you have to add shipping, Duty, and then VAT on to that total so you would end up paying closer to £50.

However, the pics and description do help you if you attempt to make something similar for yourself ;)

Alternatively, you can find a steel bolt with the correct thread and use that to help. Either screw it through the pushing and then against the wood of the body and carefully tighten it so it pushed the bushing out (although sometimes the bushing will start to rotate with the bolt), or use some levers on the head of the nut to carefully lever the bushing out. However, you need to take great care to protect the front of your guitar from any damage (you are applying a LOT of force) and you have to slowly work 360 degrees around so that you pull it up as straight as possible. If you are impatient and rock it to one side, the hole will be damaged and you will have problems keeping it in the guitar when you refit it.

Use a scalpel or similarly sharp modelling knife to carefully cut around any finish around the edge of the bushing. There is a real risk of chipping the finish.

I would lightly dampen the inside of the hole for the bushing and leave it overnight. That will help the compressed wood fibres recover so that it is a tight fit when you replace the bush. When it comes to re-installing the bush the best option is to use some form of press to push it back in. Alternatively, use a rubber mallet and flat plate over the top to tap it in slowly. Taking great care to keep it square to the hole.

It's not an easy job, but unless you can find a workshop with the specialist tools, there's no real alternative.

Hope that helps

Andy :beamup:
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Re: Problem re-attaching broken ground wire

Postby Will_m » Tue Jul 05, 2011 6:18 pm

Hi Andy, many thanks for such a detailed post. I was searching for some solutions online and found a possible fix by way of inserting a soldering iron into the post, leaving it for a few minutes and then gently easing the bushing out by the peg. Just tried it and it seems to have worked fine, I only pulled straight up from the peg so hopefully it won't have made the hole any bigger.

My problem now is that the ground doesn't seem very effective when attached to the same place as before, the buzzing disappears almost entirely when I pinch the end of the ground wire with fingers, presumably making me the ground. However touching the ground wire to the bridge as before still leaves almost all of the buzz remaining is this normal? I don't remember having to touch metal on the guitar to stop it from buzzing before.

I've not put all the parts back in place yet, pickups, cavity covers etc, could this be the reason?
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Re: Problem re-attaching broken ground wire

Postby zenguitar » Tue Jul 05, 2011 8:59 pm

First of all, I am presuming that your new string ground is connected to the ground on your lead via the case of the pot as it was previously. As long as that's there, it should be working OK.

With the original fitment the bare ends of the wire are trapped between the metal of the bushing and the wood of the guitar.

The trick with the soldering iron works because the heat expands the bushing so when it cools it's no longer a tight fit. The heat can also dry out the wood of the body, making it shrink back.

The sum effect is that the bushing is no longer a tight fit in the hole. And as it was relying on that tight fit to make the connection, you now have a poor connection. You will probably find that you can now pull the bushing out fairly easily without applying the soldering iron again.

To get it working properly, you need to reduce the hole back to it's correct size. That is why I suggested damping the wood inside the hole and leaving it over night. The compressed wood fibres will absorb the humidity and expand close to their original size. One acceptable use for your soldering iron would be to put some damp cotton wool into the bushing hole and then push the hot soldering iron down the middle. The steam will be forced deeper into the grain and wood fibres. But again, you need to leave it over night to be properly absorbed. And with either method you might have to make more than one application. Once you've tried that a few times and it is still loose, you might want to water down some wood glue (2/3 glue, 1/3 water) and use a cotton bud to paint the mix on the walls of the bushing hole. Once it has fully dried (minimum overnight, ideally 24 hours) it should get things tight enough.

Are you using a new ground wire or have you just pushed the old one back? If you are using the original wire you will find that it has also been compressed over time. It is definitely worth using a new piece of wire rather than attempting to re-use the old piece. Remember, it's dirt cheap so it's a false economy trying to re-use it.

You might also consider going to a slightly thicker gauge wire than used before, or using one with a solid core rather than a stranded one.

There should be enough there to get you up and running again. But please, don't use the soldering iron trick again, the same thing that makes it work makes the refitted bushing far less effective than it should be. If you don't need a lot of force to insert a bushing, then it's too loose. And be careful about picking up tips and instructions online, for everyone like me who is trained and has decades of experience there are tens of well meaning, self taught amateurs who have quick fixes that they don't really understand.

Andy :beamup:
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Re: Problem re-attaching broken ground wire

Postby Will_m » Tue Jul 05, 2011 11:18 pm

The fit still seems pretty tight, I had to use a mallet to get it to go back in and certainly couldn't pull it out just with grips again. To start with I was just wrapping the end of the ground wire(the other end was soldered to the volume pot)around the bridge post so there was around 3cm of bare wire in contact with the post. This only made a small difference to the noise as opposed to holding the bare wire by hand which almost eliminated it entirely.

In order to be properly grounded how does the ground wire need to be attached? ie just reasonable contact or fully soldered or held with pressure etc etc.

I'm just trying work out the cause of the lack of grounding regardless of the fit of the post, or are you saying the only way to ground it is to have it very tight in the post hole?

By the looks of things the grounding wire before was only taking pressure from above from the post so I wouldn't of thought the fit would have been a major issue as the wire wasn't against the sides. I have tried a new wire too, much thicker gauge but couldn't detect a change.

I think I'll try and do a little video tomorrow to try and better explain the problem as its quite hard to describe properly.

Once again thanks for all the help. :D
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Re: Problem re-attaching broken ground wire

Postby zenguitar » Wed Jul 06, 2011 12:01 am

By the sound of things you have a good fit Will. Three cm of bare cable in the bush hole is stacks-o-plenty. And it just has to be a very tight friction fit. No solder required. The only thing that comes to mind is that the hole from the control cavity to the hole for the bushing is coming out below the depth the bush reaches.

Will_m wrote:By the looks of things the grounding wire before was only taking pressure from above from the post so I wouldn't of thought the fit would have been a major issue as the wire wasn't against the sides.

The way it works is that the string ground wire HAS to be trapped between the side of the bushing and the wood of the body. That's the only thing making a good connection. And if that was wrongly laid out initially, it would explain how the wire pulled free.

I'm afraid you're going to have to pull that bushing again. Use the soldering iron again if you have to, but then wet the inside of the bushing hole and leave it overnight so that the wood fibres can recover. And heat it for as little as possible.

Next morning, thread a new length of hook-up wire through with 3cm stripped bare at the end. Then use something to pull that bare wire up through the hole so that 3 or 4mm of copper wire is out of the hole. When re-fitting the bushing make absolutely certain that those few mm are still above the body and take extra care to make sure they are trapped between the bushing and the wood 90 degrees away from where the wire enters the bushing hole before hammering the bushing home again. As you drive the bush home, it will draw those exposed ends inside.

That should ensure you have an excellent mechanical connection with the ground wire trapped between the bushing and the wood of the body.
How does that all sound?

Andy :beamup:
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Re: Problem re-attaching broken ground wire

Postby ef37a » Wed Jul 06, 2011 4:44 am

Andy,
Out of interest what is the threadform in that bush?

I ask because I used to make various bush pullers and "pushers" for an entirely different purpose (M5,M6... internal threads) and I found I could usually find a suitable bolt and a gash socket to do the job.

Can you get at both sides of the bush? If so it can be pulled back in place....Talk of hammers and guitars scares me!

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Re: Problem re-attaching broken ground wire

Postby . . . Delete This User . . . » Wed Jul 06, 2011 7:52 am

not it can't be pulled back in....

(these bushes are the ones under the bridge, into which the bridge mounting posts / height adjusters are fitted...

there's a significant piece of guitar body still underneath them, not like machine head bushings for example, where both sides are accessible...


i use an old knackered socket, with a felt washer glued on the front face, and an appropriately threaded bolt to remove them, much as dave suggests....

the felt washer is important , as often the force required to pull straight out can bruise the finish around the bushing..
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Re: Problem re-attaching broken ground wire

Postby ef37a » Wed Jul 06, 2011 8:22 am

Ah!
I used to always be buying crap 5quid socket sets from IAG and similar and built up a variety of ID's and OD's. They were cheap enough that I used to drill out the square drive hole on some with a 1/2horse drill press and a cobalt bit.

You can use a rubber tap washer instead of felt.

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Re: Problem re-attaching broken ground wire

Postby zenguitar » Wed Jul 06, 2011 12:45 pm

I do it the same way as you and Max described. I linked to the StewMac item because the pics and instructions on how to use it are far easier to understand than writing a detailed description here. And they also list the common thread sizes ;)

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Re: Problem re-attaching broken ground wire

Postby Will_m » Wed Jul 06, 2011 5:22 pm

Cheers guys have left it damp to expand again overnight and I'll have a go at the grounding tomorrow.
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Re: Problem re-attaching broken ground wire

Postby zenguitar » Wed Jul 06, 2011 8:25 pm

Cheers will, and don't forget to arrange the bare wire in a way it is definitely trapped between the bush and wood.

You'll soon be up and running again :)

Andy :beamup:
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