Anyone ever use these? I broke off a small thread tap in a hole I am tapping and can't get it out. A friend told me a cobalt drill bit might be hard enough to drill out the broken piece. Anyone?

Sometimes you can work them back out with a left-hand twist standard drill. Just go real slow. Chances are any drill bit will ruin the threads. They make broken tap extractors that are basically 2 prongs that engage the grooves of the stub. If yours is too small for that I'd try the left hand bit first. Works every time on brokem exhaust bolts. Just plan on a bigger hole or Heli-Coils.

If the tap is close enough to the surface you can take a sharp center punch and give it a couple of hard raps and they will often shatter to the point the pieces will fall out if you invert the piece and tap it with a plastic mallet. If the part is critical, spend the bucks and have it EDM'd out by a good machine shop.

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Originally posted by fla3006:
Anyone ever use these? I broke off a small thread tap in a hole I am tapping and can't get it out. A friend told me a cobalt drill bit might be hard enough to drill out the broken piece. Anyone?

STOP! Get a carbide endmill and remove it that way. You need a flat bottom cutter to clear you a path so you get a straight shot at the hole. Is it a through hole or a blind hole? What size is the screw?

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Originally posted by malm:

quote:

Originally posted by fla3006:
Anyone ever use these? I broke off a small thread tap in a hole I am tapping and can't get it out. A friend told me a cobalt drill bit might be hard enough to drill out the broken piece. Anyone?

STOP! Get a carbide endmill and remove it that way. You need a flat bottom cutter to clear you a path so you get a straight shot at the hole. Is it a through hole or a blind hole? What size is the screw?

And BTW, don't forget to get the mill, LOL.

EDM @ Briely's = $$$$$

mill @ jeffe's = ?

Hog Killer

Thanks fellows. I did not mention it is not a firearm. It is a 105 year old Emerson ceiling fan motor, a very valuable and rare model. The body is brittle cast iron, the thread is 4-40, a tiny through-hole. Think I need to take it to a machine shop before I make matters worse.

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Originally posted by tiggertate:

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Originally posted by malm:

quote:

Originally posted by fla3006:
Anyone ever use these? I broke off a small thread tap in a hole I am tapping and can't get it out. A friend told me a cobalt drill bit might be hard enough to drill out the broken piece. Anyone?

STOP! Get a carbide endmill and remove it that way. You need a flat bottom cutter to clear you a path so you get a straight shot at the hole. Is it a through hole or a blind hole? What size is the screw?

And BTW, don't forget to get the mill, LOL.

Silly me. I figured the "band of bubbas" had the equipment and know how to do just about anything. Never mind...

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malm: I figured the "band of bubbas" had the equipment and know how to do just about anything.

How else do you think I got myself in this fix? (I'm taking your advice, thanks!)

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Originally posted by fla3006:

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malm: I figured the "band of bubbas" had the equipment and know how to do just about anything.

How else do you think I got myself in this fix? (I'm taking your advice, thanks!)

If you would like, you may ship it here, I'll fix it for you...

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Originally posted by malm:

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Originally posted by tiggertate:

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Originally posted by malm:

quote:

Originally posted by fla3006:
Anyone ever use these? I broke off a small thread tap in a hole I am tapping and can't get it out. A friend told me a cobalt drill bit might be hard enough to drill out the broken piece. Anyone?

STOP! Get a carbide endmill and remove it that way. You need a flat bottom cutter to clear you a path so you get a straight shot at the hole. Is it a through hole or a blind hole? What size is the screw?

And BTW, don't forget to get the mill, LOL.

Silly me. I figured the "band of bubbas" had the equipment and know how to do just about anything. Never mind...

Silly malm, mills are for kids!

Bubbas all have massive Black and Decker 3/8" reversible hand mills. Wealthy bubbas have even finer built Dremel mills.

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Originally posted by tiggertate:
Bubbas all have massive Black and Decker 3/8" reversible hand mills. Wealthy bubbas have even finer built Dremel mills.

Thanks, I needed that!

and truly creative bubbas have firestrom 18v cordless, for shadetree machinin'!!

Forrest,
4x40? YIKES!! the hardness of the tap would require a carbide that small.. all i have that small is either diamond dremels or HSS.

jeffe

Fwiw cobalt is still hi-speed steel with a bit of cobalt (5%) for extra heat and abrasion resistance.....it's not a lot better than hi-speed steel....it's primarily used in production where carbide is deemed not suitable.

Carbide is the way to get it out....or EDM...or prayer....it's up to you.

Another question from bubba: what is EDM?

One side:



The other side:

Sorry Forrest, I missed the 4-40 part. Too small for most conventional fixes. Is the part small enought to put in the freezer? It might shrink the stub enough to let you worry it out.

Harry, there's nothing to get ahold of and it's in there pretty tight, and as you can see it is damned small.

EDM is short for "Electronic Discharge Machine". It is an "old" but very effective process using a high intensity spark to eat away metal. Using shaped electrodes, it is the process Magna-Port uses to cut their odd shaped ports in gun barrels. from the pictures the job looks like it could be a turd. Save yourself some problems and let a machine shop do it for you. Remember, the more you stir a turd, the worse it stinks!

Malm, from the pics, is there an end mill cutter small enough? (will need to be like the top two holes)

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Originally posted by malm:
EDM is short for "Electronic Discharge Machine". It is an "old" but very effective process using a high intensity spark to eat away metal. Using shaped electrodes, it is the process Magna-Port uses to cut their odd shaped ports in gun barrels. from the pictures the job looks like it could be a turd. Save yourself some problems and let a machine shop do it for you. Remember, the more you stir a turd, the worse it stinks!

I have 4 EDM machines send it to me I will burn them out and repair for less than 100 bucks plus shipping. But you should find a local I will give you a heads up EDM machines are expensive!!! Expect to pay $50 an hr. with a setup fee or a minimum fee. Look for a Plastic Injection Mold Makeing factory EDM's are the tools of that trade and are common.

Get some dental burs from your dentist. Use them in your dremel tool. They will cut that tap to pieces very quickly.

Doug, I like that idea! I'll sure give it a try.

Ted, I'll keep you in mind. Like I said, it's a fairly valuable antique, would be worth $100 if there are no other solutions.

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Originally posted by fla3006:
Malm, from the pics, is there an end mill cutter small enough? (will need to be like the top two holes)

I'll be honest with you, when I seen that first photo I thought they were pictures of my ex wifes thighs. Then I seen the second photo and realized that wasn't her number.

Go with the EDM. There is more control and for that small of a hole, the outcome is more certain.

Forrest, Briely has EDM equipment in their shop. Run it over there and let them give you an est.

Hog Killer

Take it to any good machine shop and ask them to Plunge a .0625", 2 flute, Solid Carbide end mill, through from the back side. It should take at tops 15 minutes for them to do it although you will be charged a minninum fee. I do it all the time.
Thanks, Doug

OK, since I'm a cheapskate (according to an EX-wife), try this. Soak the hole(both sides) with a penetrating oil for several days. Then find a flat-blade screwdriver small enough to fit in the hole. You may have to use those glasses screwdrivers. Tap the top of the screwdriver with a small hammer while twisting it. I've had taps and other screws come out this way. Its worth a try.

Forrest,

Get a diamond coated dremel bit and hit from the back side, get it fixed and drink beer.

Before you try that, grind a small needle nose plier to fit in the hole and try to turn it our, snap ring pliers will work sometimes also.

I'm a machinist over here in Japan working in the air wing, this is actually a common problem I've dealt with. D Humbarger hit it right on the money, most dental bits these days are a R321 grade carbide which is tougher and more resistant to chipping. A tap that small, plus the position it's in will wreak havoc on a end mill, carbide or not. Depending on the size of the bit, you can either bore out the majority of the bit and knock everything out with a scribe, or cut a large notch in the middle of the tap until it's almost flush with the actual workpiece, than give it a few sharp blows from a center punch with a hammer. Round the end of the center punch slightly so it'll fit into the center of the notch but not allow the punch to flow outwards.
If you don't feel comfortable with this, the EDM process is definitly the way to go.

fla3006:

Let me say a carbide end mill is very brittle. There is nothing worse than snapping off a carbide end mill inside your 4-40 tap. Then you have a piece of metel in the hole harder than a preachers dick. You have a couple of options. EDM is sure bet. Tigging a piece to your tap is another. Shattering it and redrilling it larger and tapping it larger. Making a plug and retapping it. Knocking out the broken tap and tigging up the hole then re drilling and tapping it.
I hate seing jobs like this. You usually loose your shirt when quoting them.
Longshot

The tap extractors that brownells sells work great. I've used them several times with great success. Now if I'd just learn to quit using a tap until it breaks, I might not need them.
-Don

I have good luck punching them out in a through hole

In blind holes, punching them to pieces and hoping the pieced can be pryed out has not worked

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Originally posted by Don Markey:
The tap extractors that brownells sells work great. I've used them several times with great success. Now if I'd just learn to quit using a tap until it breaks, I might not need them.
-Don

I have broken hundreds of taps in 20 years of moldmakeing.. extractors only work for the person or company that sold it to you. YES you can carbide any tap 10-32 or bigger but be aware you WILL break your $20. End Mill doing so and there is always thread damage. The EDM method is the BEST!!! tap removall meathod period! But be awear your Fan piece will have to be subjected to a total submerging in di-electric fluid (oil) during machining.

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Originally posted by ted thorn:

quote:

Originally posted by Don Markey:
The tap extractors that brownells sells work great. I've used them several times with great success. Now if I'd just learn to quit using a tap until it breaks, I might not need them.
-Don

I have broken hundreds of taps in 20 years of moldmakeing.. extractors only work for the person or company that sold it to you. YES you can carbide any tap 10-32 or bigger but be aware you WILL break your $20. End Mill doing so and there is always thread damage. The EDM method is the BEST!!! tap removall meathod period! But be awear your Fan piece will have to be subjected to a total submerging in di-electric fluid (oil) during machining.

Unfortunatly I don't have access to a EDM. I've broken several 6-48 taps and all came out fine using an extractor, I did break a couple of fingers through the process. And only once did I have to retap the hole larger. But maybe I'm just lucky.
-Don

Gentlemen, thanks for all the good suggestions. I took it to a machine shop, they milled it out and tapped it for me. Didn't even charge me. They have an EDM and said they would have used it if the mill didn't do the job but it did. I'll sure be more careful next time when I tap threads. Thanks again everyone.

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Originally posted by fla3006:
I took it to a machine shop, they milled it out and tapped it for me. Didn't even charge me.

I'd like to have heard that story!

Were they able to keep the hole original? I have milled out broken #4 taps in the past, where you could get a straight start with a stubby fluted end mill, but given the vintage part, I would probably have gone with the EDM. But I'm glad it worked out for you!

Yes sir, they were able to mill it straight on, can't even tell there was a problem. (they didn't charge me cause I was referred by an acquaintance, long story!)

I'm not realy shocked that they cut it out on a mill. I'm shocked that there was no charge. If he was not a friend in the past he is now.