Broken Tap Removal (Again)

[rake60]

20 minutes before quiting time today I made a tool teaching error that caused a hole to be drilled too shallow for the programed tapping depth. The machine attempted to tap the hole with predictable results. The tap bottomed out and naturally broke off flush with the face of the part.

Telling the guy who will be following you, "There's a tap broken off in there, have a nice night.", will get you a nasty reputation real quickly! :-[

I happened to have a a broken solid carbide end mill in my tool box. It was quickly ground to a chisel point. In less than 10 minutes the spiral flute tap was drilled through leaving just the flutes that were easily popped out with a jewelers screwdriver. By the time the 2ed shift man's evening was to begin the broken tap was out, the holes were re-drilled to the proper depth and it was ready to restart the program at the tapping process.

If you ever break a solid carbide end mill, DON'T throw it away! It just might come in handy some day!

Rick

 

[DICKEYBIRD]

Nice save Rick. Can you post a picture or sketch of the drill bit you made? I need to learn how to do that one!

 

[rake60]

It's not much to look at but here is the one I use at home.

It's just a simple chisel point ground on the end of a piece for a broken carbide end mill.
Spin it fast, about 1800 RPM and feed it slower than you've ever fed anything before.
It will sound like a mini train wreck but it will drill out a HSS tap.

In fact I had an opportunity to use it at work once again today.
10-24 taped holes and no spiral taps available, so we programed it to just go in .200" to give it a good
straight start and planned to hand tap the holes from there. It went in .200 and the tapping head revered....
The tap did NOT reverse! LOL We drilled the broken tap out with a home made 1/8" carbide drill just like the
one you see here. The rest of the parts were machine tapped .100" deep and hand tapped the rest of the way.

Rick

 

[tattoomike68]

I have had luck with carbide circut board drills. It was the first Time I ever drilled a tap out.

In a non steel part I would chemicaly mill the tap out. even urine, salt or pool clorine would attack the tap and rust it to nothing in short order.

If you have ever been fishing in the ocean you will know that you can rust a part to hell in one single day.

Others may chime in with other chemical combinations that work as well or better.

 

[rake60]

Yes we do have another thread here somewhere about that.

Small taps broken off in nonferrous metals such as brass of aluminium can easily be dissolved
by simmering the part in a saturated solution of Alum and water.
It's not a quick process. It might take 8 to 12 hours for a 1/4-20 tap, but it does work every time.
It turns a HSS tap into a rusty sludge that will basically pour out.

Rick

 

[Seanol]

Guys,
One of the things that has worked well for me is using an automatic center punch as an impact chisel. I work it around in a circle backing the tap out as I go along. I have used this with success on taps from 1/4-20 up through 5/8ths. I do not envy trying this on 4-40!
Hope this helps,
Sean

 

[Don Huseman]

I have found out that using high pressure air helps. I hook of my aqualung tank and use the second stage at 175 psi. On my air nozzle I have the small tube about .60 in dia. By blowing in the high pressure air and using the Walton tap extractor I get most broken taps out. The secret is to get the broken pieces out so the big parts can unscrew.