How to extract a broken string tree screw.

[John Yungbluth]

Pleased to present for your consideration. . . . . . . . .

I was mounting a string tree roller on a nice Korean Fender Squier headstock in an existing hole and, even before it tightened up, the screw failed and broke off even with the surface of the headstock.  Looking at the screw pieces I believe it was substandard, the diameter was thinner, missing material at the fail point.

FUBAR

I just did this, and starting to ponder options.  Any one have any experience with extracting a very small diameter screws from a very visible position?  

I could slide the tree back a little and drill another hole.  The roller tree base would cover the broken screw, but my first choice is to get it out somehow with minimal finish damage and reuse the existing hole.

The screw broke with minimal downward threading pressure being applied.  So it might be in there very loosely.

Thought about making a acrylic template and predrilling a guide hole the same size as the screw.  Trying to work a small screw driver down on it and reversing it out.  Maybe a small drill bit, in reverse would grab it and back it up enough to grab with a needle nose pliers.  Or drilling it out.

Any insight would be greatly appreciated.

John

[Joshua Levin-Epstein]

The gizmo Stew Mac sells for this purpose works well. I used it for removing the shaft of a Schaller tuning machine screw I broke off 40 years ago. I 'm pretty sure the string tree will cover the plug .

Or you can use theirs as a template for building your own. There's an article on frets.com about making a hollow drill bit out of brass tubing.

As an aside, there were two screws that I broke on that particular headstock (you mean you need to drill pilot holes in maple...?). 40 years later I saw there was enough shaft sticking out to be grabbed with fret nippers, a tool I was not aware of 40 years ago. I think needle nose pliers are not the right tool and will make matters worse.

I think you would be ill advised to try to drill the broken shaft. That's not much drill bit and I'm guessing it would make a nice ragged hole right next to the piece you're trying to remove. On the front of the headstock. Making life much more miserable.

I had success with the Stew Mac tool. I even used it to remove screws broken off on the peg box of my old Juczek bass, probably broken off when the bass was made!

[Dave]

If it's not too tight... Try to (carefully) epoxy the end of a metal rod (or toothpick) to the broken end of the screw (carefully, so the epoxy doesn't glue the screw in!), and then back it out?

[Frank Ford]

Sorry, but epoxy won't work in that application.  It will take a LOT of torque to unscrew that little guy.  The bad news is that many of those little screws are hardened steel, and not easy to drill out, even if you can get the drill to run straight enough.   We use left-haded drills sometimes because, if the drill grabs the screw it will tend to spin up and out.   Tricky stuff at best.

Generally the best solution is to use a hollow drill to drill around the screw so it can be lifted out and replaced with a dowel and a new screw.  StewMac has a kit for this, or you can get just the hollow drill:

http://www.stewmac.com/Luthier_Tools/Types_of_Tools/Routers_and_Bit...

[Howard Klepper]

You can make your own hollow screw extractor from tubing, as Frank shows somewhere on his site.  Drilling it out would be messy--the bit will keep slipping off the screw and into the wood.

The other possibility for taking it out without damage is to use a micro carbide burr (not a drill) in a dremel or (better) a flex shaft to cut a slot in the end of the screw and screw it out.  You can get them at around .020" or .5mm.

No big deal to plug whatever hole you leave.  it's not like losing value from a collectable.

[Scott Supak]

I've used the brass tubing trick a time or two with good results. It is kinda slow and you will probably have to re-file the teeth a time or two, especially in maple. I'm sure the StewMac unit works great, but this will get you through in a pinch.

[George Roberts]

The nice thing about the telescoping brass rod, is that you can use one that has an inner diameter that matches the outer diameter of the screw.  Then the next size up of the brass tube will cut a plug that exactly matches the hole.  That also allows you to align the plug with the grain in the same direction as the surrounding wood.  The tubing is available at most hobby shops, and is much less expensive than the StewMac product.

[John Yungbluth]

Gentleman, thank you all for your insights. 

I was able to get out and find the brass tubing today.  The 1/8 tubing did the trick.  I noticed that the teeth started to flare out slowly.  So each time I blew out the dust, I spun the tubing against a fine mill file and brought it back to diameter.

The broken piece is out.  Tomorrow I'll make a plug and take care of that step.  I'll try the larger brass tubing process to make the plug.  I have a broken fragmented maple neck in my cadaver pile I'll make the plug out of.

The plug should be completely under the string tree roller when installed.

Thanks again everyone, I'm sure I'll be back with another hobbyist question down the road.   

[John Yungbluth]

Confessions of a hobbyist.

 Still living, still learning.

As I noted above, my home made 1/8 drilling tool seemed to flare out slightly at the teeth end as I used it.  I had to file it back each time to keep it round.  This flaring oversized my hole slightly as I drew the bit out each time. Now my plug sized tool is undersized.  Made a plug too loose to use. 

I should have done a few practice runs on scrap to develop a feel for the handling, and plugging process.   I'm still going to be under the string tree luckily.

Now I'll try getting a strip of scrap maple off the cadaver neck to round out for a new hand shaped plug.  Hope I can get a deep enough piece off the heel to keep the grain oriented.  But I think to get a long enough starter piece,  I'll wind up with an end grain plug showing.

  

[George Roberts]

Hey John,

It helps if you use what old-time machinists called "peck drilling".  That's where you drill a tiny bit, then back the drill out to clear the chips, and then a tiny bit more, etc.

To manage the flaring, I put a drill shank of the right size into the plug cutter and while it is turning, pinch it with a smooth pair of pliers.  This takes it back to the right size, and actually work hardens the brass.

You could also try making another plug cutter the next size larger, and use a regular drill to open the existing hole to that size.

Good luck! 

[Paul Verticchio]

Two bits of info:
Your plug will be completely covered by the base of the string tree. Grain orientation is moot as most of the plug will be removed by drilling for the new screw hole. No worries.

Also, remove 1/16" from the base of the E&B string tree to establish the correct break angle over the nut.

Great work so far. You're on your way to a pro-quality repair.

Best of luck.

[John Yungbluth]

Everyone.   Thanks for your insights pointing me onto the correct path to remove and plug this issue. 

Lesson learned.

George, I like the idea of reshaping the brass end of the cutter with a center rod and smooth pliers.  I'm sure by constantly filing it back to shape I messed up the thickness and integrity of my cutter and led to mines' failing to hold shape on every use. I'm going to spend some time next week practicing "peck" drilling and making plugs on the maple cadaver neck. 

Paul, thanks for the hint on removing 1/16 off the bottom of the E & B tree.  That completely would have gotten by me until I strung it up.  Now I only had to run in the mounting screw once.

Thanks again everyone.

Like I've said before about some of my projects, out of the dumpster, onto my bench, and up on frets.net for advice.

John

[Walter W Wright]

the key detail here is to set your drill to unscrew, so that with luck the tubing will grab the screw and back it out without you having to drill all the way down around it.