Sheared-off screw head

[Buddabing]

Hello,

I was tightening a screw on my pinball playfield and the top of the screw sheared off. Of course, it sheared off when the entire screw is embedded in the wood, so it is impossible to grip the screw with pliers or vice grips.

I believe that I will have to get a good fastener in there somehow. How do I remove or drill out the screw?

You should know:
1) The only power tool I have is a Craftsman rotary tool (with dremel-like attachment)
2) I have next to zero woodworking knowledge
3) There are two of these screws, one is in an invisble location on the playfield, and one is visible. So I would like to avoid "collateral damage".
4) Pinball playfields are plywood, 1/2" or maybe 5/8". The screws in question are either plain wood screws or "fasteners".

I am thinking I can rent (or borrow from my next door neighbor who is Mr. Power Tools) a small drill press and a metal drilling bit.

I would appreciate any input from the wookworking gurus.

TIA,
Buddabing

[ahofle]

Not sure if this would help, but Sears has 'damaged screw remover' bits that grip the screw with sharp edges.  Not sure if it would work, but I would imagine a small enough bit might be able to get it out?

[mccoy178]

Since it is a plywood play field, couldn't you attack it from the bottom where you couldn't see any damage?  From the top, if the head is completely broke off, which it sounds, your best bet may be a drill press, making certain you can hit it dead on straight.  From the bottom, I would remove enough wood around it so that you could get some vice grips on it and twist it out.

[krick]

When this happens to bolts in metal, you can center punch and drill a small hole in the center of the broken off bolt.  Then you use a bolt extractor to remove it.

Unless the screw is fairly large, you're probably *screwed*.

I'm not sure but you *might* be able to cut a slot in the top of the screw with a dremmel and use a flat screwdriver blade to remove it.   If it's totally flush with the wood surface, I'm not sure you'll be able to do it without damaging the surface.  You might need to do some repair work on the wood when you're done.

[PetitMorte]

one method that may work...

use your rotary tool to carve a small slot in the top of the screw neck, turning the broken screw into a flathead screw.  Then carefully unscrew it

If there's enough clearance, you could use a thin cutoff disk to make the slot.  If there isn't, you may want to get one of those tiny tiny tiny engraving tips to make the groove in it.  A steady hand, and a good deal of patience and you should have a slot deep enough to use.

You may also want to try a drop of liquid soap on it before you start unscrewing.  Hopefully it'll seep in and lube the screw up a bit for extraction without harming the wood or the paint.

[nostrebor]

Based on your description, the only suggestion that has merit is the attack from the bottom method. I would be tempted to use a utility knife or chisels to "carve" out the area on the back around the screw, until I could get surgeons forceps on it. I would not be wanting to use a power tool for this. Too easy to damage the playfield by overcutting/drilling.

[Bomber]

Not sure if this would help, but Sears has 'damaged screw remover' bits that grip the screw with sharp edges.  Not sure if it would work, but I would imagine a small enough bit might be able to get it out?

Here is a picture of the bit. Although I'm not sure how useful it would be if the entire screw-head has sheared off. Make this another vote for attack from underneath with a hand-tool.

[struby]

I'd probably get an equal sized drill bit and just drill right through the screw, if it doesn't pop out at some point in the process, but I don't know if you have the drill/bit for that.

[PetitMorte]

Actually that damaged screw bit looks like "The Right Tool For The Job".

It probably doesn't cost much, and since it's *designed* for this type of situation, it'd probably be your best non-discructive bet.  From the look of the bit, the big, tapered pointy end would go into the head of a stripped out phillips screw.  The tiny, pokey spiked end would go into the neck of a sheared-off screw and grab it.

[krick]

The "grabit" is designed for a stripped out screw head, not a *missing* screw head...

http://www.ronhazelton.com/tips/Grabit_Screw_Removal_System.htm

[ahofle]

True, but if the bit is small enough would it really matter?  It's basically just digging into the metal to grip it.  Only question would be if they make a small enough one.

[Nannuu]

The screw removal is only for stripped screw heads, don't try that one.  And don't try to drill out from the top.  In plywood the bit will most certainly pop off to the side of the screw shaft and make a nice nasty hole right next to it in which case you still won't get the screw out.

Go from the bottom.  Once your in far enough, grab the end of the screw with some vise grips and slowly try to twist the screw until it comes through the bottom.  This can be tricky since you need a lot of pressure from the grips to twist the screw, you might actually damage the shaft to the point that twisting will just shear the bottom of the screw too, leaving an even shorter shaft in the plywood.  That's what I'd try though.

[krick]

This guy has the same problem with his guitar neck....

http://p082.ezboard.com/fguitarsbyfenderfrm20.showNextMessage?topicID=1542.topic

And here's the screw extractors one of the posters referrs to...
http://www.stewmac.com/shop/Tools/Screwdrivers/Screw_Extractor_Set.html

[PetitMorte]

*THAT*'s the ticket!  Those buggers work really well.

[krick]

Someone with the same trouble.  A sheared off screw on a pinball playfield...

http://groups.google.com/group/rec.games.pinball/browse_frm/thread/ac79b0b567e4387d/56dd3f368fbc8e7d

[Buddabing]

Someone suggested using a hole saw with a diameter just enough to cover the screw shaft. Then patch the hole with a dowel. The new screw head may be large enough to cover the dowel if the hole is small enough.

I don't know how small hole saws get, though.

[Tahnok]

Why a hole saw? Why not just use a normal bit? Most dowels are installed in furniture using just a normal drill bit, not a hole saw.

[mccoy178]

Hey rookie , what is the diameter of the broken screw?  Is it countersunk or perfectly flush?  Oh, and outside of being sure to eat your vegetables, for the love of the game, predrill next time!  If it was an old hole, lay off the 'roids there Bonds.

[Buddabing]

@mccoy178:
The screw is a plain old wood screw, about 1/8" in diameter by 1/2" long.

The screw broke off below the surface of the wood.

I have learned my lesson about predrilling. 

@tahnok100:
There's a screw in the way. I dunno if there's a good way to drill that exactly through a screw.

[struby]

If it below the wood surface, but is not out past the wood, the dip beneath the wood should make it easier to drill out:

I would just suggest heavy gloves maybe leather if you have them around, starting slow, maybe trying to give the top a little pretap, hold the front of the drill/the bit with one hand.  I don't do alot of detailed carpentry, but I can see how that might be a little rugged for a pinball table, but if you are careful and take your time, I think it could come out ok, might depend alot on if it broke off flat or slanted, it if is easy to start the hole, the rest should just be being patient and keeping it straight, keep it straight.

Where is this on the table?

[Tahnok]

@tahnok100:
There's a screw in the way. I dunno if there's a good way to drill that exactly through a screw.

Get a sharp bit and be carefull. Whether or not you can drill through a screw depends really on the diameter of the screw and how it broke off. If you can get the bit to sit into the top of the screw, it shouldn't be a problem. But then again, I'm really no expert on pins.

[danny_galaga]

some really good thoughts here! when i was an auto electrician i had to deal with broken screws all the time. i can tell you this now though. you will NOT be able to drill out a screw that is small and in wood. to do that you need to centre punch it, drill it and use an 'easy out'. to punch it hard enough will probably drive the screw straight out (for better or worse) anyway. which might be an option now i think about it!  also it will be impossible to try and drill the same size as the screw. it will just scoot over to one side and into the plywood.my own initial thought was to try the cut a slot in it with the dremel. also check underneath. maybe the screw is longer than the wood is deep? then you can use vice grips and screw it straight out. a hole saw needs a pilot drill in the middle, and of course exactly in the middle of where you would want to hole saw is- the screw! i also cant see how using a drill press is going to help. unless its something im not familiar with normal drill presses are designed to sit on a bench (or on the floor) and you manouver the piece underneath it. i cant imagine how you would hold a whole playfield under it!

[nostrebor]

The odds are VERY good that you will damage your playfield if you try to drill from the top. This is based on lots of experience in dealing with this scenario. If you want to completely avoid damaging the top, only approach this from the back, with non-powered tools.

[Popcorrin]

If you were going to drill it out from the top I would use a left handed drill bit, put your drill in reverse, and apply very light pressure.  Hopefully the bit will grab ahold of the screw and screw it out.

[krick]

If you were going to drill it out from the top I would use a left handed drill bit, put your drill in reverse, and apply very light pressure.  Hopefully the bit will grab ahold of the screw and screw it out.

They have left handed drill bits, just for this purpose.

[danny_galaga]

so have you resolved this problem yet? and how so?

[Lilwolf]

I've had that happen by breaking drill bits flush more then breaking screw heads off.  (then I stopped trying to predrill with such a thin drill bit

@mccoy178:
The screw is a plain old wood screw, about 1/8" in diameter by 1/2" long.

The screw broke off below the surface of the wood.

I have learned my lesson about predrilling. 

@tahnok100:
There's a screw in the way. I dunno if there's a good way to drill that exactly through a screw.

[Buddabing]

so have you resolved this problem yet? and how so?

I cleared off all metal parts near the screw. Then I used a magnetic stud finder to find exactly where the screw was. Next, I drilled a small hole to find the screw. I then enlarged and deepened the hole until I could get some needle-nose vise grips around the screw. Then the screw came out. I repaired the hole with wood putty.

[nostrebor]

so have you resolved this problem yet? and how so?

I cleared off all metal parts near the screw. Then I used a magnetic stud finder to find exactly where the screw was. Next, I drilled a small hole to find the screw. I then enlarged and deepened the hole until I could get some needle-nose vise grips around the screw. Then the screw came out. I repaired the hole with wood putty.

You might want to add that you did this from the back face of the PF.

[Buddabing]

That's right, here's a picture of my vise grips clamping the screw shaft.

The hole I made is actually larger than it would have been had I drilled out the screw from the top, but I did not have to touch the top of the playfield at all. So I think this method worked out well.