Main Forums >> Guitar Technology
        Print Thread

Pages: 1
Huge Longjohns
long-serving member


Joined: 10/04/03
Posts: 2007
Loc: Where the black rocks stand gu...
Aaagh, screw rusted and head sheered off--help!
      #1022058 - 03/12/12 04:06 PM
Taking the bridge plate off one of my Yammy tellies and the screw was so rusted that its head crumbled under the screwdriver. So how do I get the rest of the screw out without making a right mess of the top of the guitar??? ZEN HELP!!!!!

--------------------
"The man who questions opinions is wise. The man who quarrels with facts is a fool." Frank Garbutt, inventor & industrialist


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Hugh RobjohnsAdministrator
SOS Technical Editor


Joined: 25/07/03
Posts: 22026
Loc: Worcestershire
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022059 - 03/12/12 04:10 PM
Depends how much of the screw shaft is left standing proud of the woodwork. You might be able to file flats on opposite sides, then use a molegrip to clamp on and rotate out. or you could use a fine hacksaw to cut a slot in the shaft and use a screwdriver to rotate out. Worse case is you might have to drill it out and replug.

hugh

--------------------
Technical Editor, Sound On Sound


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Frisonic



Joined: 27/01/10
Posts: 3787
Loc: London, United Kingdom
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Hugh Robjohns]
      #1022062 - 03/12/12 04:29 PM
Let's hope one of Hugh's first two suggestions work and once you've got the offending detritus out I recommend you think about treating yourself to one of these!

--------------------
Strictly project and just for fun


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Hugh RobjohnsAdministrator
SOS Technical Editor


Joined: 25/07/03
Posts: 22026
Loc: Worcestershire
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Hugh Robjohns]
      #1022076 - 03/12/12 05:15 PM
If there is little or no shaft above the woodwork, preventing you from filing flats or cutting a slot, then you could use an 'easy out' (miniature) screw extrator tool like these from amazon:

http://www.amazon.co.uk/Laser-3744-Combination-Screw-Extractor/dp/B002TD10 P0/ref=pd_sim_sbs_diy_1

Hugh

--------------------
Technical Editor, Sound On Sound


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Random Guitarist



Joined: 01/04/08
Posts: 554
Loc: West Sussex UK
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022080 - 03/12/12 05:41 PM
I wouldn't use mole grips, too much chance of slipping. I don't think a typical bridge scre will have enough meat for an easy out.

Get a piece of tubing with an inside diameter just big enough for the screw. Cut/file some saw tooth type slots in one end. Put the other end in your electric drill and running the drill in reverse gently cut down around the screw with the new tool you have made.

This will drill down around the screw removing the minimum of wood, at some point the scre will bind inside the tubing and inscre out the rest of the way. Then you replug and redrill the hole.

I've used this technique a number of times and it is pretty infallible, the drill speed means you cut through the laquer cleanly and the old screw body acts as a guide for the cutter.

Good luck,

Grant.

--------------------
I've never liked a solo violin, you need at least five for a proper fire.


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Random Guitarist



Joined: 01/04/08
Posts: 554
Loc: West Sussex UK
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022081 - 03/12/12 05:44 PM
Should have said 'metal' tubing, although it is obvious.

--------------------
I've never liked a solo violin, you need at least five for a proper fire.


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
zenguitarAdministrator
active member


Joined: 05/12/02
Posts: 8884
Loc: Devon
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022082 - 03/12/12 05:45 PM
What Hugh said, he beat me to it

And you are fortunate that the sheared screw is in such an easily hidden location. That more than anything else makes the job a lot easier to take on.

One extra tip that might be worth a try. There is a likelihood that the rust/corrosion has worked its way down the shaft of the screw. That can make it a much tighter fit than it was when it was put in. If there is a little 'head' still protruding you may only get one chance to get a decent grip on it. Consider some fine shavings from a wax candle and put them around the protruding head. Then apply a hot soldering iron, with a fine tip, to the protruding metal of the screw. The heat will make the screw expand a little, which will help it loosen up, and the wax will melt and run down the threads to provide lubrication.

You don't want to make the screw so hot that it burns the wood/finish, just enough heat to make the metal expand a fraction. A similar technique with a soldering iron is used to remove frets too.

Andy

--------------------
When the going gets weird, the Weird turn Pro.


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
DAGGILARR



Joined: 22/09/10
Posts: 700
Loc: Exeter, Devon.
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022083 - 03/12/12 05:53 PM
The best trick I was ever shown about getting old screws out is ALWAYS to tighten them a bit first this way you achieve a bit of movement, risking pressure in the other direction also as screws are tapered this will open up the hole a bit (if it is a wood screw) Not withstanding this when you do get some purchase on this offending stubb the same principle will apply try gentle pressure in the tighten direction first.

A good close up picture would probably help any who may have constructive ideas

Is it steel into wood? or steel into steel machine screw ? The application of a soldering iron onto the stub can cause a useful expansion stretching the hole if its into wood also helping WD40 in if its into steel (though this will in effect lubricate the bit you need to grip as well)

If there is room and you have someone who can help, assuming a grip can be achieved with vice grips wiggle the grips while the other person administers shocks to the shaft ( no carry on jokes here ) a centre punch is good for this.

--------------------



Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Huge Longjohns
long-serving member


Joined: 10/04/03
Posts: 2007
Loc: Where the black rocks stand gu...
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022100 - 03/12/12 07:09 PM
Quote:



If there is little or no shaft above the woodwork, preventing you from filing flats or cutting a slot, then you could use an 'easy out' (miniature) screw extrator tool like these from amazon




Sorry should have said, the shaft end is probably 1mm below the surface of the wood.

--------------------
"The man who questions opinions is wise. The man who quarrels with facts is a fool." Frank Garbutt, inventor & industrialist


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Hugh RobjohnsAdministrator
SOS Technical Editor


Joined: 25/07/03
Posts: 22026
Loc: Worcestershire
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022110 - 03/12/12 07:24 PM
Then you either need to use one of these miniature screw extractors, or the core drill technique described previously, and re-plug the hole afterwards.

Hugh

--------------------
Technical Editor, Sound On Sound


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Huge Longjohns
long-serving member


Joined: 10/04/03
Posts: 2007
Loc: Where the black rocks stand gu...
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022112 - 03/12/12 07:27 PM
How do the extractors work, Hugh, they're a new one on me?

--------------------
"The man who questions opinions is wise. The man who quarrels with facts is a fool." Frank Garbutt, inventor & industrialist


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Folderol



Joined: 15/11/08
Posts: 3728
Loc: Rochester, UK
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022114 - 03/12/12 07:31 PM
Ouch!

What is the size of the screw?

One extremely tedious method I've used with a sunken screw is to drill two very fine holes (about 0.8mm - one of my PCB drills) side-by side in the stub then drill out larger until they join. Lubricate well, and heat treat as suggested above, then ease out with a watchmakers screwdriver.

P.S.
Ideally you don't want the holes to reach the edge of the screw.

--------------------
It wasn't me!
(Well, actually, it probably was)

Edited by Folderol (03/12/12 07:32 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Random Guitarist



Joined: 01/04/08
Posts: 554
Loc: West Sussex UK
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022115 - 03/12/12 07:37 PM
The conventional screw extractors work by drilling out the centre of the existing screw and then screwing on of the easy outins int the hole left handed. The left handed thread means that as you screw the easy out into the hole it bits into the sides of the hole in the original screw. The harder you turn the more the easy out bites into the screw and the screw undoes.

IN practice the easy outs frequently break if you are even slightly ham fisted, leaving you with a hardened undrillable lump in the middle of your screw. Also you have to drill your centre hole quite accurately for such a tiny screw. I'm not a professional engineer, but I've successfully restored a couple of cars, and I would not use an easy out unless every other possibility had been exhausted.


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Folderol



Joined: 15/11/08
Posts: 3728
Loc: Rochester, UK
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022116 - 03/12/12 07:41 PM
That's my experience too

--------------------
It wasn't me!
(Well, actually, it probably was)


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
zenguitarAdministrator
active member


Joined: 05/12/02
Posts: 8884
Loc: Devon
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022132 - 03/12/12 08:33 PM
Broken inside the wood. Grant's method is the way to go, it'll do the cleanest, most effective, job.

Use one of the other screws that came out without problems to help you pick a suitable piece of metal tubing.

Have fun

Andy

--------------------
When the going gets weird, the Weird turn Pro.


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Random Guitarist



Joined: 01/04/08
Posts: 554
Loc: West Sussex UK
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022160 - 03/12/12 10:43 PM
I'm going to back-track if the screw is slightly below the wood.
Has the screw sheared off flat enought that you might be able to centre punch it? and do you have a pillar drill?

If yes to both then I would try punching and drilling first as you'll have a slightly smaller hole to plug.

If the top of the remaing screw is very ragged or you don't have the drill then I'd stick with a home made centreless drill. The teeth don't have to be super accurate or sharp, they don't even need to be terribly hard, you can use a piece of brass tube.

Last thoughts for coreless drilling on a sunken screw are that I'd use a regular drill bit to carefully start the larger hole as without the screw in the centre of it the core drill can skate around, and start with low speeds.

I hope this is helpful.


Regards,

Grant.

--------------------
I've never liked a solo violin, you need at least five for a proper fire.


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Hugh RobjohnsAdministrator
SOS Technical Editor


Joined: 25/07/03
Posts: 22026
Loc: Worcestershire
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Random Guitarist]
      #1022165 - 03/12/12 11:06 PM
Wot ee zed! A hollow core drill is the way to go with this because he screw you're trying to remove is presumably very small. The easy-out tools work by using a counterclockwise threaded screw that bites into a pilot hole you drill first into the broken screw, and as it bites, it unscrews the offending screw. But you nee to be gentle and very accurate otherwise the tool is quite likely to snap or shear itself, making things even worse!

Looks like you're going to ave to drill and replug. Good job it's under the plate ;-)

H

--------------------
Technical Editor, Sound On Sound


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Jumpeyspyder



Joined: 20/01/06
Posts: 1249
Loc: Yorkshire
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022178 - 03/12/12 11:31 PM
Hi Huge

Probably not the 'correct' method, but you may be able to leave the broken screw where it is and stick a new bridge on top with a different mounting hole pattern to hide it.

Best of luck


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
zenguitarAdministrator
active member


Joined: 05/12/02
Posts: 8884
Loc: Devon
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022196 - 04/12/12 12:38 AM
And +1 for brass tube. It's nice and soft and will grip the steel screw very well once it starts to 'bite'. Easy to cut the teeth with a triangular file, and widely available in assorted internal diameters from model shops everywhere. And definitely worth plugging the end that you chuck in the drill with a piece of softwood dowel so the chuck can get a good grip.

I think you can sense a broad agreement here Huge

Andy

--------------------
When the going gets weird, the Weird turn Pro.


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Huge Longjohns
long-serving member


Joined: 10/04/03
Posts: 2007
Loc: Where the black rocks stand gu...
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022245 - 04/12/12 10:09 AM
Great advice everyone and, as Zen says, if I do totally cock it up at least it's under the bridge plate and there are still four other screws holding it on!

--------------------
"The man who questions opinions is wise. The man who quarrels with facts is a fool." Frank Garbutt, inventor & industrialist


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
DAGGILARR



Joined: 22/09/10
Posts: 700
Loc: Exeter, Devon.
Re: Aaagh, screw rusted and head sheered off--help! new [Re: Huge Longjohns]
      #1022354 - 04/12/12 06:18 PM
It seems you could expend a lot of effort trying to preserve the hole,,, why? once the offending bit of steel is out a hole is an easy thing to fix, an oversize dowel and a carefully matched drill bit, some good glue, jobs-a-goodun; then relocate a pilot hole for the replacement screw.

--------------------



Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Madman_Greg



Joined: 07/12/06
Posts: 729
Loc: The back of beyond
Re: Aaagh, screw rusted and head sheered off--help! new [Re: DAGGILARR]
      #1022405 - 05/12/12 12:29 AM
The brass tube is its fact a neat trick.

You could try another tack with it

Tube o/d – wider than screw o/d

Tube i/d = smaller than screw diameter

Drill a shallow taper into the tube, maybe 5 mm in depth, you might have to grind a drill to get the right shallow taper profile. Or you could flare it if you have something to do that.

Cut your teeth in the tube

Use the drill in reverse as stated, the friction on the taper on the screw might loosen it

--------------------
Madman_Greg


Post Extras: Print Post   Remind Me!   Notify Moderator     Back to top
Pages: 1

Rate this thread

Jump to

Extra Information
0 registered and 7 anonymous users are browsing this forum.

Moderator:  David Etheridge, James Perrett, zenguitar, Martin Walker, Forum Admin, Hugh Robjohns, Zukan, Frank Eleveld, SOS News Editor,  
Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled
Rating:
Thread views: 4221

October 2014
On sale now at main newsagents and bookstores (or buy direct from the
SOS Web Shop)
SOS current Print Magazine: click here for FULL Contents list
Click image for October 2014
DAW Tips from SOS

 

Home | Search | News | Current Issue | Tablet Mag | Articles | Forum | Subscribe | Shop | Readers Ads

Advertise | Information | Privacy Policy | Support | Login Help

 

Email: Contact SOS

Telephone: +44 (0)1954 789888

Fax: +44 (0)1954 789895

Registered Office: Media House, Trafalgar Way, Bar Hill, Cambridge, CB23 8SQ, United Kingdom.

Sound On Sound Ltd is registered in England and Wales.

Company number: 3015516 VAT number: GB 638 5307 26

         

All contents copyright © SOS Publications Group and/or its licensors, 1985-2014. All rights reserved.
The contents of this article are subject to worldwide copyright protection and reproduction in whole or part, whether mechanical or electronic, is expressly forbidden without the prior written consent of the Publishers. Great care has been taken to ensure accuracy in the preparation of this article but neither Sound On Sound Limited nor the publishers can be held responsible for its contents. The views expressed are those of the contributors and not necessarily those of the publishers.

Web site designed & maintained by PB Associates | SOS | Relative Media