Shop Tip #??? Broken Tap Removal
idbruce
Posts: 6,197
Hello Everyone
Yea, Yea.... I know it has been a while since I have shown my face or added my 3 cents, but here I am 
Over the years, I have provided several shop tips about lessons and various tricks I have learned. Well today I discovered a new one and I thought I would share it with you folks.
While cutting 10-32 threads into one of my parts, I broke the tap 
Having many hours into fabricating this part, you can only imagine my dismay and the raging expletives.
I hate breaking taps and throughout my life, I have broken a my fair share of them, probably more than most people, and out of all the taps that I have broken, I may have been able to extract two, three, or four at the most, with today being one of those instances.
Luckily for me, when the tap broke today, it broke off about 1/16 of an inch above the surface of my part. 1/16 does not provide a lot of metal to grab onto, but being unwilling to just abandon my part, I put some thought into the problem and my past failures at broken tap extraction. Being a triple fluted tap, I came to the conclusion that I needed a three prong tool to match the three indentations of the tap and then it dawned on me, I have the perfect tool already , a salvaged keyless chuck from an old cordless drill I figured it was at least worth a try
While keeping the jaws of the chuck firmly against the face of my part and aligned with the indentations of the broken tap, I slowly but surely hand tightened the chuck upto the broken tap. Once it was aligned and firmly engaged, I tightened it with a little more torque. Being content that it was as good as it was going to get, I decided to try and untread the broken tap from my part. To my amazement, it worked flawlessy
My part was salvaged, which makes me happy, and I also learned a new trick, that I wish I would have learned long ago
Comments
nice one
Mike
That is a nice way to remove a tap that protrudes above the surface and is large enough for the chuck to grasp. For smaller bits (2-56 to 6-32) or ones that do not protrude above the surface you can use 3 sewing needles. Push the needles into the three flutes of the tap and then use a small drill chuck to hold the 3 needles and then turn the drill chuck by hand to remove the tap. It may require a bit of patience and fiddling but I have succeeded more often than not.
When I worked as a machinist I broke too many taps.
Lesson 1: Peck drill the hole so it's as straight as possible.
Lesson 2: You MUST use tap fluid or another lubricant such as high-strength Alcohol.
Lesson 3: Take your time and back out the tap frequently.
4-40 taps are the worst because they are so tiny.
Walton make a special tool with three extendable prongs. They work ok for M4 and above, but its hard to keep them straight for M3 (around #4). You can buy spare prongs though. https://www.waltontools.com/products/remvtap.htm
Where those don't work I've had success grinding everything flat/flush, mating to a heavy plate, and using a right-sized punch to crumble the remaining tap into smaller pieces, since its so hard but brittle, and the pieces usually just fall through. Initially I was worried this would damage the thread too much, but finish the tapping with a new tap and things seem fine.
I do like Bruce's chuck idea and I'll try this out next time if there's enough tap protruding
The best tap removal system is EDM, too costly for the average hobbyist. Taps are hardened and can't be drilled, best solution don't break one, use Tap magic, after you've broken enough taps you develop a feel when not to over torque it.
When selecting a tapping fluid, use one that's designed for the material you're tapping. Tapping fluids designed for steel are not the best choice for use with aluminum and vice versa. And brass -- ugh! -- I've probably broken more taps in brass than in any other material. It's just -- sticky!
-Phil
Yea Genetix, I have had plenty of 4-40 taps snap for me.
DigitalBob, this break came as a complete surpise. It was the last of several 10-32 threads that I had to tap and I was probably about 75% through it. I was using plenty of tapping fluid and backing up regularly. When it broke, I was barely using any torque. It caught me completely off-guard and I was truly surprised when it did break.
The tap was probably a bit dull and most likely had a stress fracture in the structure.
You have to buy quality taps too., some taps don't have consistent heat and are too brittle. I find the lowest quality taps are Hanson
Long time Bruce.
Nothing like breaking off a tap or frozen screw at the wrong time (ever a right time?)... As you noted, it demonstrates the stress relieving abilities inherent in ones vocabulary...
If you find yourself in a bind, check out the rescue bit for larger stuff. Not sure the 1/8" one would have helped you, but it beats any Dremel bit hands down. Had a frozen set screw in a motor shaft connection (Kirk screw, long and extremely expensive). Went through the collar like butter, no damage to the shaft at all. The bit in a Dremel tool was so controllable I was able to go almost paper thin and split the collar without making a mark on the shaft.
I recall a machinist saying that you should ONE set of taps for Steel, and ONE set of taps for Aluminum, but I don't remember why.
Please, don't see this as an advertisement or endorsement of any product or manufacturer, because it isn't, for sure.
https://mscdirect.com/basicsof/high-performance-taps
From the age of eight thru fourteen (1963-1969), I've sold a lot of tap tools, from behind the counters of my grandfather's hardware store.
I used only to listen to customer's orders and pick the goods from the shelves, automatically, without ever daring to ask why any of them was selected, or preferred.
"The custommer is always right"; used to be our "mantra", and ever worked a treat.
Thanks to give me the chance to recall my youth, and also fill a long-standing vacuum, in my knowledge base.
Henrique
Another trick I've learned many years ago (now at the industry, from 1976 thru 1988):
Never; never mix the tool sets used to cut/drill/mill/solder/thread carbon steels, with the ones used to work with stainless steels.
Reason: contamination of the finished stainless steel parts.
Even the working areas, the uniforms and protection equipments used to be segregated by color, and warning labels.
Bruce guess what I broke this morning, a M4 tap in 3mm thick stainless.
Like you there was only about 2mm of tap projecting through the far side, so I tried your idea, and it works surprisingly well.
I used a small irwin keyless chuck whose shaft is 1/4" hex, but put it in a 1/4" manual nut driver (screw driver handle for 1/4" bits) to be able to control the torque
Big thanks for taking the time to share your tip. I don't really have anything similar to offer, other than if you ever see on of these 'portable drill presses', buy one
https://drillmate.com.au/product/drillmate-portable-drill-press/
Tubular - Thanks for sharing your success story
I am glad it worked out well for you 
I have found this to be very true
I have also found that if you have a drill press and have the space to use it it works a lot better than trying to free hand drilling
Also for taps that small than a #12 bolt you can use a very light weight screw gun or drill that has torque control ring and set it to a setting that is just enough to move the tap forward but still ratchets use just enough pressure for the tap to move downward but not enough to break the tap ( but use extreme caution when doing this if not done correctly you will break the tap ) one note when the tap starts to becomes dull use a new tap or it will become stuck an break very easily
One thing that this does if your tap is giving you a hard time going in take the drill bit and run it back and forth a little bit to enlarge hole a little bit so the tap goes in easier but do not get carry away with this because you will make the hole to big OR you are not going in straight into the material and you will know it ( the first thing I noted should be the second thing you do not first thing you do )
This can also be done with bigger taps but only if the thickness is less than 1/4” and it is not stainless steel or very hard type of steels are not recommended results are very poor at best
I done this many times and the success rate is very high if done correctly it saves time but you do need to use cutting oil for success
One thing that just learned recently is that you can use real butter for a cutting oil on stainless steel
I work for a seafood processing company and you have to use food safe products when you do any kind of repairs
When I use a drill for a 1/4-20 tap my boss asked if I was going to break the tap doing this I was repairing the treads on a block of steel that had been already been tapped
I told no as long as you use the right torque settings and you do not use to much pressure downwards when running the drill I did have his attention for this one because he had never seen someone do it this way
[ I have been thinking about making a drill press using a drill that has a torque control ring for when I have a lot of holes to tap but I do not have a lot of free time on my hands anymore so if I find my self having do a lot of tapping to do I will be doing soon
I have a project in mind for making a few LED light strips for a battery operated emergency lighting for my house
I have the LED module and the boost converter power supply module but just do not have the time to put it together ]
My dad's method: thread a nut onto the available partial thread, get out the mig. Weld the nut to the remaining part of the tap then unscrew it.
silicone spray helps ease a tap out reducing the torque needed.
I always clean my taps with a file card and contact cleaner prior to storing them. this removes residual lubricant that may not compatible for the next tapping job.