[slashmaster]

I was drilling a pilot hole through a motor armature and the drill bit snapped. It broke deep in the hole so can't clamp anything on it to pull it out. Turning it upside down and tapping it doesn't seem to work either. Anyone have a trick to get it?

[awemawson]

EDM drill to pop it out.

[Geof]

Will it be a through hole? Drill from the opposite end with a carbide drill until you touch the tip and then punch out the broken bit.

Or try to drill it out with a carbide bit down the existing pilot hole. This may not work because a carbide drill should not be used on a pilot hole as there is a good chance the cutting edge will chip at the edges of the pilot hole and then you might have a broken carbide drill in the top end of the hole.

Unfortunately what you have discovered is a very good reason to not use a pilot drill.

[slashmaster]

Thanks Awemason, What's EDM?

Thanks Geof, Yes it will be a through hole, going through the other side is possible but difficult. It's a 5/64th bit though, is that too small? I don't have any carbide bits at all. What would happen if I just used another bit? I know it will be ruined but I need another set anyway.

[TXFred]

Have you got a broken carbide end mill? If so, you can grind a tool like this.

Broken Tap Extractors Tool - Detailed info for Broken Tap Extractors Tool,screw extractor,Broken Tap Extractors Tool, on Alibaba.com

Run high RPM's and feed down very slowly.

I've done this to drill out a broken HSS tap. I don't see why it wouldn't work on a broken HSS drill.

Frederic

[Geof]

What size is your final hole? 5/64" is very small and I hold little hope for success mostly because even if you do successfully drill from the other end until the hit the tip of the broken drill you have virtually no area for a punch to bear one. Sorry to be so gloomy.

I guess EDM (electric discharge machining) could be feasible but expensive.

[slashmaster]

Thanks Geof, thanks TXFred. Maybe it would help if I told you what I was trying to do first. I've got a little motor not tight enough on its belt and there is no proper way to adjust it. I'd like to use an endmill to turn the 9/64th mounting holes into slots but as far as I know there is no such thing as one that is 1 1/4" deep. So I tried to drill 2nd holes next to them, on one the bit broke and the other the bit worked its way into the original hole. Now what do I do? I have a roundfile, I was thinking about trying to use that as an endmill but what rpm do I spin it at?

[macpod]

Has anybody else tried using an Alum solution to rust away a broken nail/bit (assuming whatever you were drilling in isn't a ferrous metal)?

[DJPLAST]

Find a shop with a ram type EDM machine and have them put your slot in for you, and at the same time they will disinigrate the broken drill.

[ssuebsak]

I though you need EDM or the one call "super drill" to burn it out complete.

Should the EDM drill electrode side same as the core drill diameter of you drill bit.
after complete the drill bit can take out in a small piece.

But if you material is not metal it may not work ( erosion process can't complete )

But if you have some photo to share what happened look like it may help to imagine to take it out.

http://www.octec.com.tw/e_na.htm

http://en.wikipedia.org/wiki/Electri..._hole_drilling

[txcncman]

This thread is why people need to both take machinist classes and gain experience in the work place before calling themselves machinist.

First, you are going to break tools. Be prepared to buy more.

Second, you are going to have to buy special tools. Don't use the excuse "I don't have one." Just buy it.

Third, EDM is Electrical Discharge Machining. A quite common machining method, especially when dealing with harder materials like broken drills and taps.

Fourth, I doubt you have the skills for this, but a machinist could probably make an external bracket for your application to be able to have some adjustment.

Fifth, maybe you should have purchased a new belt of a smaller size to run a little tighter.

[underthetire]

Has anybody else tried using an Alum solution to rust away a broken nail/bit (assuming whatever you were drilling in isn't a ferrous metal)?

Yes. It works. It's very slow, like a week sometimes.

[dansutula]

Slashmaster,
I've used small dremel bits to grind out broken screws. You may need a diamond burr to grind a hardened steel or carbide drill bit. If you can weaken it first, perhaps you could use a "hammerdrill" in an attempt to crush and break the rest of it.
Regards,
Dan

UNDERTHETIRE - I'm trying to get in touch with you regarding the enclosure. Is your PM Box overfull? Please PM me. Thanks!

[nateman_doo]

This thread is why people need to both take machinist classes and gain experience in the work place before calling themselves machinist.

First, you are going to break tools. Be prepared to buy more.

Second, you are going to have to buy special tools. Don't use the excuse "I don't have one." Just buy it.

Third, EDM is Electrical Discharge Machining. A quite common machining method, especially when dealing with harder materials like broken drills and taps.

Fourth, I doubt you have the skills for this, but a machinist could probably make an external bracket for your application to be able to have some adjustment.

Fifth, maybe you should have purchased a new belt of a smaller size to run a little tighter.

Take it easy, he just asked how to remove a broken drill bit. He didnt ask to be judged?

OP, I take a carbide endmill of similar size and slowly feed it into the hole with my flood coolant on. Less then 1ipm.

[michaelthomas]

Everybody knows that good machinists were born with all the skills they need. No real machinist has ever broken a drill bit and used the situation to learn from it......whatever. (This being said in the most sarcastic tone possible)

I feel your pain......I had to use Geofs suggestion only a short time ago to get a broken drill out of a much shallower hole than yours. It took me half a day with less than ideal equipment. In retrospect, I probably could have remade my part in less time, but I did gain some knowledge from the ordeal.

[Dano523]

Drill rod two sizes down, take one end to a point, the either black tape or shrink wrap the sides of the drill rod so only the point make contact with the broken drill bit down the channel.

From welder rod holder clamp on the rod pointed tip down, ground the welder to the work piece, then bond/weld the tip of the drill stock to the broken bit( just go straight down until you get the arch/hear the machine cycle, the release the drill rod from the rod holder.

From there, just spin the mill in reverse to back the broken section back out via the protruding drill rod chucked up.

[nateman_doo]

Drill rod two sizes down, take one end to a point, the either black tape or shrink wrap the sides of the drill rod so only the point make contact with the broken drill bit down the channel.

From welder rod holder clamp on the rod pointed tip down, ground the welder to the work piece, then bond/weld the tip of the drill stock to the broken bit( just go straight down until you get the arch/hear the machine cycle, the release the drill rod from the rod holder.

From there, just spin the mill in reverse to back the broken section back out via the protruding drill rod chucked up.

That sound scarey, but WOW thats a great idea!!:idea:

[Connor]

That sound scarey, but WOW thats a great idea!!:idea:

I broke a small bit off in the head of my G0704 when doing the 3 bolt mod. It broke about 3/8" below the surface. I drilled down with 1/4" bit then used a slightly larger bit to drill a hole next to the original one using the side wall of the 3/8 hole to help get started. I then upsized the hole until it broke through to the original and then was able to push the broken bits out with a small punch. I then went back to the 1/4 bit to finish the hole and continued upsizing till I reached proper diameter. Of course, this all depends on weather or not the hole you were drilling was a pilot hole and how much larger you can go.