View Full Version : How do you drill out a broken bolt

Stefan Antwarg
12-27-2004, 11:32 PM
Is it as simple as taking a regular drill bit of the approximate size and drilling it until it grinds away?


Bruce Shiverdecker
12-27-2004, 11:43 PM
Not exactly. There is a bit called an "easy out." You first drill out the center of the bolt, then insert the easy out, turning counterclockwise until it is removed.

They are available at and hardware/ big box store.


Carl Eyman
12-27-2004, 11:51 PM
There is nothing easy about an easy out. Rememberm the bolt broke because the strain was more than the bolt could take. Now we are trying to get it out with something even smaller in diameter. Sometimes it works, usually only because one applies heat, rust busting oil, or some other magic elixir.

Kevin Arceneaux
12-27-2004, 11:59 PM
Cutting torch

Boyd Gathwright
12-28-2004, 12:21 AM
.... I agree with Bruce, be very patient but Carl has a good point also ;).


Randy Meijer
12-28-2004, 5:09 AM
And if the bolt doesn't come out, you can drill a slightly oversized hole and insert a little gizmo called a helicoil which will give you a new set of threads of the same size and pitch as the original. Most common application of the helicoil is for restoring sparkplug holes that have been stripped out.

Michael Cody
12-28-2004, 7:34 AM
Is the bolt in wood or steel?
Is the hole a thru-hole or blind?
Is the bolt brass, steel, SS, hardened, etc.. ?
Do you have easy access to it or is it in a difficult spot?
How important is cosmetics in the area where it's broke?

They are dozens of techniques but a lot depends on what you have to work with. Drilling out a hardened bolt can be a real PIA, an easyout might work, might not. If you are in a restricted spot or there is a lot of junk around, then you maybe can't heat or drill to easy (provided we are talking metal).

Perhaps you can use a dremel to cut a slot in the remaining material of the bolt and take it out w/a flat headed screwdriver. If it's got some length exposed, you can grind a flat on it and use vise grips. If it's in a thru-hole, use a drill that is 1-2 sizes smaller than the hole, then tap out the remain material to clean up threads. If it's in wood, you can use a plug cutter to cut out the bolt/screw, plug - redrill - replace the broken fasteners. The info you gave is to minimal to really give you a definitive answer.

Tony Falotico
12-28-2004, 7:38 AM
Stephan -- they make a reverse thread drill bit, check a good hardware store for one. Chuck it in, put your drill in reverse and go to it. When you get the hole established, jamb the drill bit in by pushing very hard (our pull sideways). The drill will catch, and if the bolt isn't rusted or otherwise 'welded' in, she'll spin right out. It works best with 1/4" or larger bolts, I have been fairly successful with this method.

Good luck ........

Stefan Antwarg
12-28-2004, 8:04 AM
The bolt is stuck in my cast iron woodstove. It is in a blind spot - cannot get to the other side. There is still some sticking out from the surface. It is in an OK spot to get to, but it is inside the stove. I am not sure what the bolt is made out of, but it withstands extreme hot tempuratures.


Glenn Clabo
12-28-2004, 9:39 AM
Been working around seawater and ships for most of my life so I can say there is a little bit of an art to doing this.
First, soak the bolt with liquid wrench...rust buster...or whatever they have locally.
Grind the bolt flat and center punch the bolt...center is most important.
To accommodate taper of easy out -
Smallest drill first...deepest.
Next size drill...less deep.
Largest drill, without ruining threads...less deep.
Soak it overnight is best...
Using largest easy out that will fit...go for it.
If that don't work...which is normal...do the helicoil thing.

www.helicoil.com (http://www.helicoil.com/)<O:p></O:p>