Help! Broke a Drill Bit off in a Broken Bolt

[Dan in Pasadena]

SO I did a search and didn’t find much that would help.

The situation is: 2 broken-off 5/16-18 bolts flush (or slightly below) the surface in the floor of my already-painted ‘55 Chevy truck - so I can’t use heat. I drilled through one of them successfully but because it was broken off below the surface the hole isn’t exactly centered - still haven't figured out how to get the remainder out without destroying the threaded hole? I may have to just open it up to 3/8”.

But as to the bolt with the broken drill bit, I found Denlors Tools offers something they call a “Rescue Bit” but they’re pricey as hell. $64.98 plus $5 shipping on Amazon for one 1/4” bit. Yikes. Anyone have a cheaper or better suggestion that won’t ****** up my new paint...much?!

 

[p_mori7]

Masonry bit at slow speed setting ? They are a carbide tip so it should chew through the broken one.

 

[p_mori7]

Small chisel or punch to try tapping out reverse direction from the way it was drilled in or to loosen it up in the hole ?

 

[p_mori7]

You say drilled through...can you tap it or bash it out from the other side ?

 

[ALLFAST]

Have you thought of using an easy-out ? Much cheaper than what you listed, and available at a good hardware store, bigbox, or autoparts store. It's reversed, and bites in as you turn out the bolt. You need to drill out an appropriate sized depth to get it to bite, and the hole diameter you end up with needs to be a tad under the diameter of the e-z out.

What's the bolt fastening ( in your cab) ?

Shawn

 

[BuffettFan]

What are they broken off in to?
The masonry bit suggestion is a good one, low rpm, carefully applied can work. Just might be another option knowing the circumstances.

 

[BuffettFan]

And a left hand twist drill bit set is a handy tool for your arsenal...

 

[BillK]

Dan,
Can you get to the bolt from the bottom ? If so just get another bit and drill up from the bottom and then use a punch to get the broken drill bit out ? I wouldnt worry too much about the threads, you can always put a helicoil in it if you have to.

The other thing I have done is use a hole saw without the center drill but I dont know if you can find one that small.

 

[Dan in Pasadena]

Im not too worried about getting out the remainder of the bolt I already drilled through. That one I can try the chisel trick - though the bolt seems pretty frozen in there - I will apply Screw-Loose, ATF/Acetone, even WD40 or some such. And if none of that works I can just drill the hole out a little oversize and tap new threads for a larger bolt.

I’m most concerned about getting out the one with the broken drill bit in it. Never occurred to me that a masonry bit would do anything but I have some so I’ll give that a try.

 

[Dan in Pasadena]

Dan,
Can you get to the bolt from the bottom ? If so just get another bit and drill up from the bottom and then use a punch to get the broken drill bit out ?...

I thought about this. The truck is pretty low but yeah, I can jack it up enough to get under there and see the bottom of the bolt. Not a bad idea, I’ll give that a shot before buying the high dollar “rescue” bit.

 

[Dan in Pasadena]

What are they broken off in to?
...

“...the floor of my already-painted ‘55 Chevy truck”

 

[MJD1]

A small tapered die grinder burr will cut thru that pretty easy.

 

[Dan in Pasadena]

Something like this? Just use it to hog out what’s left of both the bolts AND the drill bit? Ok, I own a cheapo HF angle die grinder. Guess I’d better break that thing out!

 

[Garthbrady12]

If you have a dremel, use it and a small bit you might have to buy one.. dremel out as much as you can, and then retap it. That’s if a easy out doesn’t work


Sent from my iPhone using Tapatalk

 

[frednoah]

Carbide burr in a dremel or die grinder

 

[MJD1]

Something like this? Just use it to hog out what’s left of both the bolts AND the drill bit? Ok, I own a cheapo HF angle die grinder. Guess I’d better break that thing out!

That's it. If you can set up something to prop your hands against, it may help with getting the hole centered.

 

[jeepinerdeep]

I thought about this. The truck is pretty low but yeah, I can jack it up enough to get under there and see the bottom of the bolt. Not a bad idea, I’ll give that a shot before buying the high dollar “rescue” bit.

I'm in the punching camp on this one. Nothing really good ever happens with a burr in a die grinder.

 

[Lwel9226]

I'm in the punching camp on this one. Nothing really good ever happens with a burr in a die grinder.

I agree with Jeepiner..... Use the die grinder as the last resort.....

LynnW

 

[Slednut]

I've found that if I use a hand held drill and the bit has broken off I can usually get it out with one of these.

The drill moves around so the hole usually ends up a lot bigger that you think.

 

[Dan in Pasadena]

Are you saying to drill AROUND the broken off bit to create space to use a pick and loosen the broken bit? I considered that but I’ll have to be VERY careful near the broken bit or it will “catch” the much smaller bit and I’ll end up with a second bit broken off in there too!

 

[CJM8515]

An extractor is likely to just snap in there. Been there done that. Drill from the bottom and try very hard to NOT break the bit in the bottom of the bolt. FYI LUBE LUBE LUBE and more LUBE!

 

[DeltaWye]

I'm in the punching camp on this one. Nothing really good ever happens with a burr in a die grinder.

I thought it was really good when I got a sheared off 3/8" bolt with a broken drill bit inside out of the machine I was working on. The piece of drill bit wasn't very long - maybe 1/4" - but it prevented me from drilling on-center - until I created a nice valley with a diamond burr which was more than happy to eat through that damned drill bit.

Well worth the $20 I spent on it, I only wish I'd thought of it earlier.

 

[BuffettFan]

“...the floor of my already-painted ‘55 Chevy truck”

When I think "the floor of your already painted 55 Chevy truck", I think of the sheet metal. Trying to offer possible solutions, not to argue.
I would think that there is something more substantial below the sheet metal that the bolts are actually threaded into, unless it's maybe a seat mount or something along that line with a captive nut in the sheet metal.
My thought was possibly whatever the more substantial part is might be able to be removed so as not to damage the paint, or may be able to get to the back side of the bolt hole for easier removal.

 

[rsanter]

How far does it stick though the bottom? Can you grab it with vise grips and turn it out the bottom?
Can you use a dremel cut off wheel so you can cut off the remains on the bottom then just eat out the rest of the bolt with a die grinder. Then you pick out the remains and retap the hole.

Can you put a nut on the bottom and weld that on then turn it out the bottom?

Bob

 

[Kevin54]

If the bolt is sticking out through the bottom far enough, go to TSC, or Advance Auto, and buy a set of the sockets that when you turn them the teeth will bite in to the stud so you can turn it out. Can't remember the name of them right off, but they are a lifesaver.