Technical Broken Carbide Drill Bit in Hole - What now ?

Gentlemen,

I have the great misfortune of replacing the door hinges on my 51 F1 truck. The hinge to door side features rivets. Just starting to drill out the first when the end of the drill bit breaks off. (3/16 carbide bit) With that hardened bit in there I cannot get another drill bit to dig in. (no surprise there) I went up to a 5/16 carbide but still nothing. I then got to thinking that I may have to grind down the broken bit. (By the way, there is not good access from the backside.)

Is grinding the right idea ? If so what is the best grinding bit to use ?

In the first picture you can see the hole I have dug. (Lower left) The second picture is the only thing I had in the garage that looks like it might grind. (A cheapie set, probably a time waster)

Oh yea, I have some rust to deal with, as well.

Many Thanks

 

I've broken taps off before, had to chip them out with punches. It's a pain, but usually works ok.

 

Well not an expert but there’s an old adage that says the harder the material the softer the stone. In you can find some small green mounted stones I would try that. I think Dremel makes some. Expect to use a lot of them because they break down fast. The other option is a small diamond coated burr in a high speed grinder. These burrs are quite expensive. I really don’t think grinding with another carbide burr is going to help. Tungsten Carbide is very hard and shatters fairly easy. As a last resort you might try shattering the carbide in the hole with a hardened punch and then grinding out the rest. In a machine/tool shop removing broken drills, taps is usually done with EDM (electrical discharge machining) but won’t work for you.

if you can get the other three rivets out you might be able to rotate hinge back and forth enough to slide of the rivet with carbide in it. You then could deal with what’s left.

 

If it's actual rivet, and you already got the head off, pound it out with drift. Don't need backside access for pounding out the backside.

 

Got a plasma cutter?

 

I watched a video once of a guy showing how to shatter a 1/4in carbide bit. He heated up red, the quenched with a squirt bottle of water. He did this a few times, then smacked the bit with a hammer and pieces crumbled.
Fake video? I dunno, just something I stumbled across once and have no experience doing.
Anyways, hope you get it out.

 

If you let carbide get hot when cutting a piece of work,,,,,,and cool it with water,,,,,it makes it brittle .
The tool makers at our work always use an air blower nozzle to cool carbide.

Tommy

 

Won't it just slide out of the door after the head is off the rest of the rivets?

 

This- after heating cherry red with the oxy.

 

Never had a rivet slide out, always takes a hammer and punch for me to knock them out.

 

If you have access to a plasma cutter you can hit it straight on and usually blow out the rivet (and in this case, embedded bit) without damaging the surrounding metal.

 

I wonder if short bursts would act like an EDM machine?

 

if you heat it red hot then completely cool will that change the molecular make up and let it soften enough to drill with another carbide bit.?

 

Like others have suggested; green wheel, diamond burr, depending on access. You can use heat but don’t distort the hinges.

As a side note, solid carbide is best run in a machine. It’s too brittle to run in a hand drill.

 

It looks like you are dealing with a pretty fragile piece of door there. I would probably try to stay away from any beating on it, as much as possible. From the looks of your picture it appears that you've already drilled that rivet deeper than the thickness of the door material. I would drill the other 3 rivets out to a little deeper than the door material and fairly close to the rivet diameter. That 'should' relieve the tension between the rivets and the door. Some heat and a little light tapping 'should' release the hinge from the door. Then you can cut off the other head of that rivet and drive it through from the back side.

 

I'm guessing your going to cut out the rust and replace the metal over the hinge anyway... I'd cut the whole area out, get the hinge off the old rust metal, rebuild the door, drill and tap hinge and bolt it on with counter sunk bolts. Two birds, one stone.

 

It it is a tight spot a Dremel tool is handy. You would need a good bit though.

 

Is the door riveted to the hinge AND the door? It should be bolted at one place to adjust it for closing. Get the door off and out of the way. I would not use those burrs. Buy a good quality 1/8 inch carbide endmill and put it in your Dremel, NOT RECOMMENDED. Wear GOOD shield, gloves, and operate slowly.

 

Plasma! Just don’t cross the streams. Just kidding, that whole end of the world thing is over blown.
I recently removed all of the door hinge rivets with my plasma cutter. Easy peasy.

 

I would flood it with a crawl oil, then I would put "tip clearners" > used for cleaning acetylene tips
down each side of broken drill bit as deep as possible, then use a crescent wrench as close as possible and tap with small hammer as you turn wrench, ( sounds more complicated than it is. )

 

@Bandit Billy is correct. Use a plasma cutter.

No amount of screwing around with a dremel will get it done. Carbide is very tough. The only thing that might work is welding a chunk of rod to the end and pulling it with a slide hammer.
In the machine shop if you broke a small carbide off you s****ped the part. It was too much work to pull them out.

 

In the Machine Shop, Dumprat, you could get Carbide out with a sinker EDM. Usually only if the part fit in the machine. There was however a portable machine that saved my *** more then once. Almost like a Magnetic Bux Drill Press, If you know what one of them is? Anyway it was a EDM, Magnetic base, had to control the coolant some way, it just spewed out. I would stick Clay 'Dams' on the plate damming the coolent. Used on Big Blanchard Ground plates/ Machine base's.

 

If you use grinding carbide bits use a dremel tool. it will take a while but should be able to take it down enough to break it up. I've also used an ejecter pin from a mold as they are harden steel and slowly will chip away at it.

 

Since its only a 3/16 (.187)diameter drill, you won't have much luck trying to grind it out. You will mostly be grinding the rivit around it. If you play with it long enough you may get it out, but why do all those frustrating gyrations? Either do as BB recommended and spend a just a few seconds with a plasma cutter blowing the center out of all the rivits......OR try heating it with a torch till everything is red hot and let it cool. That should destroy the rust that is helping hold the rivit. Then once its cooled, try reheating and concentrating the heat on just one rivit. When its good and hot hit it with a punch till it moves out. The cooler surrounding metal should hold everything in place. Then do it again for the next rivit.....etc. You'll spend forever trying to get that bit out by grinding........then you still have the other rivits to think about. I'd find a plasma or a torch you can use.

 

I was not meaning to try and cut the carbide with the 1/8 inch endmill. I meant to cut around it to loosen the carbide. Should have explained better.

 

The good: Rivets make a damned good fastener, as not only do they clamp the pieces together, but during the riveting operation their diameter is expanded to fit tight in the holes of all layers.
The bad: They can be a ***** to get out. You have to drill them almost all the way out (diametrically) to remove them.
The ugly: Knocking or grinding the head off then punching them out with a drift and hammer, results in bending/distorting surrounding metal.
I can't tell from the picture how deep the broken drill is below the surface, but I would try to use a bigger bit (the size of the rivet diameter) to drill down to the broken carbide. Then drill out the other 3 holes to the same size. When you can get the hinge loose at the other 3 points, twist and shout the original location enough to free the entire hinge. Gradually work your way through the layers that way. Time consuming and a pain in the ***, but a good rivet joint is tight in all directions, with no clearances like a bolted joint. Patience Gr***hopper, and good luck!

 

I have drilled through hard stuff (ceramic) with a wooden dowel. Build a dam with clay around the hole. Then put diamond lapping powder and oil around the hole. Peck drill with the dowel. Keep putting fresh lapping slurry on the hole. If you are patient it will go through. Low risk of damage to the door. Mag drill would make it easier, but I did it with a hand drill.

 

Thanks guys ! As always, some very good responses from people that have been at it for awhile. Turns out my carelessness was a big contributor. Like many of you, I figured I should be able to knock the rivet on through. The problem with that was that I was too careless to get all the rust, bondo and dirt out of the way and a fair amount of the rivet head was still there. Once I got that cleared up it punched through easily enough. I was more cautious from then on so the remaining rivets were no problem. Had to hold off on the other door till tomorrow. Back problems !
Many Thanks !

 

When I have a broken carbide drill in a part I have to get the part in the bridgeport and use another carbide endmill to peck it out a little at a time. It works but if you cant get it in a rigid vise to do this I have also just tried to brake it up with hitting it with a punch and hammer. Sounds like you got it handled.

 

Carbide sounds like more trouble than it’s worth!