Broken #21 Drill Bit in mill part.

Old Iron

Old Iron

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I broke a #21 drill bit below the top of the casting and I'm thinking I can use a 5/32 carbide end mill to get it cut out.

Wishful thinking or is there a better way to get it cut out? If not I need to order a couple end mills.

This is one of my arbor supports for my Horizontal Mill so I can mess it up. Getting another would be costly.

It is for the oil site glass and I could get by with out using one screw being as it is on the top. But I rather fix it.

Paul
 
Try chucking a piece of appropriate sized brass tubing from a local hobby store in a hand drill set on reverse. Cram it in and jerk it out. repeat until it drags the drill out.

Steve
 
is it going to be a blind hole or a through hole if it is a through hole maybe drill from other side and knock it out?
steve
 
Never had much luck with end mills (carbide) digging drills out unless its poor quality drill. If you try it I would think something like 1/8 4 flute would be better because you want to work on the center/core of the drill. Like Frank says they break and then you've got carbide stuck in there. Pick at it with dentist pick or similar. Patience and persistence and of coarse the correct words. With the support you can't drill from the other side? What about the next size up if you were going for a 10-32 thread. Sometimes a little heat will help. Hope it works out ! No pun intended.
dickr
 
It is a blind whole of sorts, It is a through whole but not through the other side. It is hollow and I did try and drive it on through but that didn't work.

I'll try some of the things you guy suggested and see what happens.

Paul
 
Any idea how deep it went before it broke? If it's not too deep, would it help to try a spot-weld cutter to remove the parent metal around the bit of bit? (That could be replaced with a plug later to allow you to start again.) Then you could grab the bit and wiggle it out.
 
To bad you don't live closer. Master Tool and Machine has an E LOX machine. We could burn it out.

"Billy G" :thinking:
 
How about drilling over it with a larger bit, or even going alongside it? If you could drag it out from there, over drill the hole, and put in a helicoil.
 
If the part is robust enough to beat on, sometimes a inertial shock will dislodge a broken drill. Whack it with a good sized hammer close to the drilled hole a couple of times. It's a small drill, so there's not much weight to work with, but it does sometimes work.

Some might suggest alum in water, same as tap removal. All you need to erode is the flutes' edges, and it should basically fall out.
 
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