Best way to remove broken off tap?

[Hemo]

So I had the tumbler on the Dolep lock kit all trued up on a lathe, filed, polished, and ready to harden. For a final fit check, I placed the cock on the squared end of the shaft, seated it tightly. Screwed in the cock screw and found it was just a millimeter or so short of tightening all the way to the surface of the cock. The screw is already cut pretty short, and I didn't want to shorten it any further. I decided I'd better drill and tap the hole just a little deeper. Drilling went fine, tapping went fine until the last gentle turn, when the tap snapped off in the hole, partly below the surface, partly just above. I couldn't get it to turn out by tapping the protruding bit with a punch, just broke off the protrusion.

I googled the usual remedies for tap removal. I thought I'd consult the gang here for advice before proceeding further. The tap is a 6-40, and about 1/4 inch is stuck in the tumbler. Any words of wisdom?

Gregg

[Scota4570]

Diamond dental burrs in a Dremil or Foredom tool is the only way I have had any success. 

Just carefully slice up the tap starting in the flutes.  I got a box of the burs from my dentist years ago.  Ask the dentist or maybe order some. 

[kudu]

Being a Machinist I feel  your pain!  A #6 screw is small 'not real small" but small . The carbide burr is a good idea. and I would guess that the tap is made from high speed steel and not a true "gunsmith tap" made from  carbon steel. Like the ones sold thru Brownells made just for gun work they are somewhat tougher not so brittle  a good investment if your doing this type of work regularly.

if you have a drill press or better yet a mill hold the piece solid in some type of vise, fixture with screw etc. and then chuck up some type of drill burr etc I think a 3 flute carbide drill works best.
get out your paitience Hat and go slow to make sure your centered on the tap and drill slow (about 700 rpm) and steady I would also use a little air at the same time as your drilling to get the chips out.

Best of luck Adam 

[Mark Elliott]

Most industrial supply companies should carry a tap removal kit that includes a carbide drill to drill out the tap.   

[flehto]

If you have a machine shop close by, have them EDM it.

I've removed broken taps by using a small, hardened punch and chipping away at it.

Have never had too much success w/ the tap removal sets.....Fred

[eddillon]

Diamond dental burrs in a Dremil or Foredom tool is the only way I have had any success. 

Just carefully slice up the tap starting in the flutes.  I got a box of the burs from my dentist years ago.  Ask the dentist or maybe order some. 

Works every time for me.  I use the burrs to remove the center of the tap.  Soon the flutes collapse.  Problem solved.

[Hemo]

Thanks for your replies, guys!
Looking through my drawers I found some Dremel carbide burrs, one round, one cylindrical, one tapered, all slightly smaller than the tumbler hole. I heated up the tumbler and broken tap to red-orange to take the hardness out of the tap, put the tumbler in a drill press vise, and using the drill press and a combination of all three burrs, I was able to clear it all out, leaving the threads intact. It appears it will work fine!
A good trick to know for the next time.

Gregg

[jerrywh]

 It is a ggod thing that you heated it up to anneal it some. That was a good idea although high speed steel doesn't anneal very good in the regular manner evidently it was good enough. 

[Daryl]

Well done Gregg!  I might have done something entirely different and probably more violent as well - perhaps.  I have sometimes been able to remove broken taps (it happens) using pins held in a backwards turning chuck, but a #6 is quite small for that.  The dental bur or de-scaling tools come in handy for many things.

[Bob Roller]

So I had the tumbler on the Dolep lock kit all trued up on a lathe, filed, polished, and ready to harden. For a final fit check, I placed the cock on the squared end of the shaft, seated it tightly. Screwed in the cock screw and found it was just a millimeter or so short of tightening all the way to the surface of the cock. The screw is already cut pretty short, and I didn't want to shorten it any further. I decided I'd better drill and tap the hole just a little deeper. Drilling went fine, tapping went fine until the last gentle turn, when the tap snapped off in the hole, partly below the surface, partly just above. I couldn't get it to turn out by tapping the protruding bit with a punch, just broke off the protrusion.

I googled the usual remedies for tap removal. I thought I'd consult the gang here for advice before proceeding further. The tap is a 6-40, and about 1/4 inch is stuck in the tumbler. Any words of wisdom?

Gregg

It's been years since I broke a tap in a tumbler. I use a 6x40 and tapmatic threading fluid
and a #33 drill and then countersink the hole the depth of one thread.If anyone taps a blind
hole without a tapping fluid it can be a disaster. You might try heating dry sand to a heat
that can't be touched and then heat the tumbler and tap to a red/orange and drop it into the sand and cover it up.
Come back in a few hours and dig it out and then,using the lathe,carefully bore the tap with a .109 end mill which
is a common 7/64 and the #33 is .113. If that doesn't work then get another tumbler or make one.

Bob Roller

[pushboater]

I had the same thing happen to me. It was a three fluted tap. I took an old specialty screwdriver bit and shaped it with three prongs to fit down into the clearance holes between the flutes and was able to back it out. Had to do it twice on the same project.

Capt. David

[M. E. Pering]

I have done exactly as pushboater (Capt. David) did with good results.  But I used tool steel, and after shaping it, I also hardened and tempered it.  I found it to work quite well.

Were you using a bottoming tap, Gregg?  For this type of work, I find bottoming taps to work best, because they stop fairly suddenly.  So when you know you are getting close, you proceed very gingerly.  On blind holes, I start with a standard tap though, since it is easier to get started straight and true.  Then I switch to the bottoming tap.  I don't use an intermediate tap, which some recommend.  Instead, I just remove the tap and clear the chips frequently. 

Matt

[Hemo]

I have done exactly as pushboater (Capt. David) did with good results.  But I used tool steel, and after shaping it, I also hardened and tempered it.  I found it to work quite well.

Were you using a bottoming tap, Gregg?  For this type of work, I find bottoming taps to work best, because they stop fairly suddenly.  So when you know you are getting close, you proceed very gingerly.  On blind holes, I start with a standard tap though, since it is easier to get started straight and true.  Then I switch to the bottoming tap.  I don't use an intermediate tap, which some recommend.  Instead, I just remove the tap and clear the chips frequently.  

Matt

Matt, I did start with a bottoming tap and used tap oil. The bottoming tap stopped short of the target depth, though it wasn't all the way to the bottom of the drilled hole, so I switched to the starting tap and made some progress until it snapped.

Thanks again, all, for your input!

Gregg

[Scota4570]

About 90% of the time I drill my hole using a milling machine, one could also use a drill press. I leave everyting in place and use the drill chuck and a transfer punch to guide the rear end of the tap.  Tapping a blind hole free hand is risky. 

With taps, especially small ones any bending action it probably going to snap the tap.  By keeping it dead straight it starts straight and won't break.  Unless.......the tap is dull.  If I hear the slightest creak noise I stop and back out.  If it binds up it will break too. 

Little 6-48 taps are usually bound up in the hole pretty good.  A tiny tap extractor won't have the leverage to do much good.  If the part is conducive tap it with a small hammer for a while.  The vibration may loosen the tap. 

[FDR]

If you have a machine shop close by, have them EDM it.

I've removed broken taps by using a small, hardened punch and chipping away at it.

Have never had too much success w/ the tap removal sets.....Fred

EDM is the correct answer. Ask me how I know!
The EDM will not damage the hole or the part.

Another Fred

[sz]

Yeah EDM is you can get it done...........or buy a new tumbler.  That may be the cheapest way to go

[Doc]

Well, my method of throwing a fit, and stomping around like a three year old has never resulted in any positive results 

Good job.

Doc

[FlintFan]

I go the milling machine route as well, but I use a solid carbide, center cutting, four flute endmill instead of a carbide drill.  The endmill cuts on it's own path, and wont deflect off of the uneven surface of a broken tap like a drill might. I raise the bed into the cutter, leaving the quill height locked.  Done dozens this way at work and at home, and have never broken a cutter or damaged the threads in the tapped hole...yet...knock on wood. 

[Hadden West]

Machine shops usually have 2,3, and 4 flute tap extractors. Although I don't recall have a 3 flute extractor for a 6 size tap. Sometimes they work and sometimes they break. If a tap is broken off clean, you have a chance, but if it's cracked and in the hole in two pieces, your chances are slim. I've removed hundreds of broken taps, in my 40 plus years in a machine shop and it takes patients, practice and luck, in addition to tools and EDM's. Not a fun day, at work, when taps start breaking.

[CoSnipe]

http://www.waltontools.com/products/extract-machsc-hand.htm

[Hadden West]

Those tap extractors will work, as long as the tap is in one piece. If it is cracked, and parts are still in the hole, you will need to try and pick out the broken piece. If you don't get out broken fragments, it will bind in the hole, and possibly break a flute on the extractor. Also, it's a lot like tapping a hole. You need to turn it, out a little, then blow out the shavings, then turn it back in, until it turns freely. When you're tapping a hole, by hand, turn the tap a little bit, then back it out, clean out the chips, clean the tap, add some more oil, go a couple treads, then repeat the process.  If you attempt to tap a hole, all at once, you're asking for trouble. Machine tapping can do it, but they are usually flooded, with coolant and working with a straight hole and tap is aligned better. Not so by hand.

[Pete G.]

That is why I absolutely HATE tapping a blind hole. I have had good results with the previously mentioned tap extractor, but they may not work so well if the tap is jammed in the hole.

[Dphariss]

So I had the tumbler on the Dolep lock kit all trued up on a lathe, filed, polished, and ready to harden. For a final fit check, I placed the cock on the squared end of the shaft, seated it tightly. Screwed in the cock screw and found it was just a millimeter or so short of tightening all the way to the surface of the cock. The screw is already cut pretty short, and I didn't want to shorten it any further. I decided I'd better drill and tap the hole just a little deeper. Drilling went fine, tapping went fine until the last gentle turn, when the tap snapped off in the hole, partly below the surface, partly just above. I couldn't get it to turn out by tapping the protruding bit with a punch, just broke off the protrusion.

I googled the usual remedies for tap removal. I thought I'd consult the gang here for advice before proceeding further. The tap is a 6-40, and about 1/4 inch is stuck in the tumbler. Any words of wisdom?

Gregg

If you have s drill press with a vise order a carbide drill (2 or 3) is better just under tap drill size and simply drill the tap out. I could tell you to order some Moly tapping Fluid while you are at it but Castrol Moly tapping fluid is Over 46 bucks a pint now..... But ti will last most people a couple of decades.  When I was at Shiloh they were breaking a lot of taps and one of the employees came in with some Slick 50 and it cured the problem. ?
Run carbide at higher speed than drilling normally and slow feed. Will cut a HS steel tap like butter. If you have a carbon steel tap you can anneal it and drill it with conventional drills. HS steel will not anneal.
I generally get stuff from MSC in 2 days no long waits.
But carbide is brittle and will shatter unless both the drill and the work  are solidly "fixed" in a drill press/mill chuck and a vise. But they are wonderful for "saving" a hole with a broken tap in it.

Dan

http://www.mscdirect.com/product/details/58580804

[Dphariss]

I go the milling machine route as well, but I use a solid carbide, center cutting, four flute endmill instead of a carbide drill.  The endmill cuts on it's own path, and wont deflect off of the uneven surface of a broken tap like a drill might. I raise the bed into the cutter, leaving the quill height locked.  Done dozens this way at work and at home, and have never broken a cutter or damaged the threads in the tapped hole...yet...knock on wood. 

This is the other carbide option and I have used it as well.
http://www.mscdirect.com/product/details/01192715

[FDR]

Or maybe this one:

http://www.mscdirect.com/product/details/88245832?item=88245832&fromRR=Y

I would have thought that the mill would have been higher priced than the drill bit. Who Knew?