Removing Broken Taps

[OlderNewbie]

Just in case you had any doubt, your post offers *no useful advice* on the question I actually asked. Sigh.

Edit: And this is puzzling, as your answers to many other questions are so often helpful...

John

Ummm.....I think you missed the useful advice.
An ounce of prevention, is worth a pound of cure. Ever heard that one before?

Want to prevent broken taps......don't buy or use cheap taps. Same thing holds true with drill bits....and many other tools or tooling.

I have many cheap taps...and dies. They hide in a separate drawer from my 'real' ones. Chase a buggered up thread....light duty work....no biggie. If I build any intricate part, and it requires tapping, I use a high quality tap, and give it every chance of working correctly....alignment, not over torquing, etc.

Good advice....


Bill

No, Bill, I didn't miss that. I get the prevention advice. Really, I do. I even got it the first time. Honest! Obviously I'd prefer not to break them in the first place. That's exactly why I have been buying new and used (but sharp) HSS taps for a while now and trying to research which work best for machine tapping of both through and blind holes, why I usually use the drill sizes for a smaller percentage thread now that I used to, why I'm looking into whether forming taps might work better for 304SS, and why I keep looking for an affordable tapping head with greater capacity than the small one I have. I hate breaking taps. I'm sure everyone else does too. Of *course* there are ways to minimize these and other risks, and advice about those ways is good to have and equally good to follow. I even have lots of questions about many of them.

But that was not what I asked about!

Please forgive me if I express grave doubt that a good quality HSS tap will never, ever break or accept for a moment the notion that nobody ever has ever broken or will ever break such a tap, whether from hitting an inclusion, accidental bottoming under power, trying to tap "one more hole" when it's become dull, because one misread the chart and drilled the wrong size hole, or for any other reason whether operator-induced or not.

I simply want to know what the best approaches are to take *when* they *do* break. Infinite advice about preventing breakage, and further stress on the importance that advice does not answer the question, and in this context it is just not useful.

John

[OlderNewbie]

The original reason for using the carbon tap was because of a smaller diameter shank. So, I suspect reducing the diameter of the shank on a HSS tap would achieve the same goal.

HSS taps can be removed with carbide bits. I have purchased a few just for that purpose, HI ROC comes to mind. Some other carbide bits are intended to drill holes in abrasive materials and have entirely different properties. If the masonry bits worked, that is one solution. My biggest problem seems to be getting the bit somewhere close to center.

Aha! Hi Roc says, "Designed to drill hardened steel in the 42-65 Rockwell c range, 135 Deg Point." A workable solution, I think, as my (perhaps incorrect) understanding is that both HSS and carbon taps are in the 60-65 Rockwell C range. Thanks, Russ. I'm still curious about whether there is a grade of carbide end mill that might be less expensive than Hi Roc drills, but as insurance policies go a few of these are not terribly expensive compared to the $110 kits Enco sells.

I did not have much trouble getting things close enough for what I did by eye, but my objective would be to fix the problem when and where it happens, when it happens in the mill. That is, I think it would be best to remove the tap while the original setup is undisturbed and I can use the drill or mill on the original center, or by indicating the piece's position in some way before removing it, if necessary, so I can relocate it there with reasonable accuracy. (For example, I might need to bring it over to the belt sander to get the tap flush with the surface or attempt to back it out first if I think there is enough purchase to be had.)

The masonry bits worked, and they're cheap enough, but I'd rather use something actually designed for the job.

John

[AndrewMawson]

OK if it happened in my shop I'd pop it out with my die sinker EDM machine. But I appreciate that most home shops wouldn't be so equipped. However there is a relatively simple chuck mounted device that can be home made that given time will also remove a broken tap however hard.

Imagine a solenoid coil mounted vertically in the mill chuck, with the moving armature having a copper tube of the tap diameter fixed to it's lower end. Now create an electrical circuit such that the solenoid is energised but fed electrically though the contact of the work and the copper tube. As soon as current flows, the solenoid pulls up, breaks the contact and the armature falls under gravity to re-make the contact. So the process repeats and it works just like a buzzer. Now arrange a fine jet of water to flush the debris away, and tweak your power supply for best results. The discharge at the 'contact' slowly but surely disintigrates the tap.

[dly31]

It would be slow but I have heard of removing the majority of a tap, drill, or extractor by using brass or copper tubing and abrasive compound in the mill or drill press. Sounds to me like a sure fire way of doing the job without damage to anything.

[RCW]

I fabricated a small part, and--as is often the case--the last operation was taping a hole. Even though I was careful, the tap broke. I ordered a "tap extractor." Waste of money. Took a small, cheap punch from HF and decided to drive out the tap. The first lick broke out big chip, so I whacked it from a different angle. It ruined the expendable punch, but the broken tap came out in pieces. I had resolved to drill out to the next larger size and re-tap, but before I did that, I looked at the hole. It really didn't look that bad. So I lubed it up and carefully fed in a new tap. A few seconds later I had a nicely tapped hole in the original size.

Would this work for you? I have no idea. Could I ever reproduce this? I don't know that either. I don't even know if this was good advice.

[spro]

Everything is good advise. It goes from every post to solution which works on the plane we understand it. This situation has been knocked out by others in indeterminate times. We may not be as pressured as others, not put to the wall. Certain things will work.
We completely miss the additional information which can disintegrate a tap.
I admit I went towards extraction when elimination was the subject. These are two different things.

[ronm]

Just in case you had any doubt, your post offers *no useful advice* on the question I actually asked. Sigh.

Edit: And this is puzzling, as your answers to many other questions are so often helpful...

John

Ummm.....I think you missed the useful advice.
An ounce of prevention, is worth a pound of cure. Ever heard that one before?


Bill

I have a feeling it was bringing his sanity into question that was the part that didn't set well...

[OlderNewbie]

Just in case you had any doubt, your post offers *no useful advice* on the question I actually asked. Sigh.

Edit: And this is puzzling, as your answers to many other questions are so often helpful...

John

Ummm.....I think you missed the useful advice.
An ounce of prevention, is worth a pound of cure. Ever heard that one before?


Bill

I have a feeling it was bringing his sanity into question that was the part that didn't set well...

LOL!

John

[Carm]

OlderNewbie

Prevention is obviously the best course...sharp, quality tools, tap drill clearance to allowed max%, lube.

Sure ya can break HSS taps.

Most of the extraction methods have been covered, and apart from the beauty of EDM types, not unreasonable to have around the shop. Left hand drills/mills, welder, punches et al.

Two more I didn't see mentioned, if allowable to yourself or possible customer, core the offender with an annular cutter or a hole saw w/o pilot. I like annulars because they leave a clean hole and are very fast.

Turn a slug that can be a fit from shake free slip to shrink/press. Loctite can work (say for drill bushing plates) or Dutch pins. You of course could tap the hole and fine thread in the replacement, being mindful of screw material!

The other is either use or make an end cutting carbide burr ( we had Severance in the tool room).
Has to be a rigid set-up, i.e. leave the work in place, clamped. The burrs don't plink like fluted cutters when leaned on. If you have some old carbide shanks and a suitable diamond wheel you can put in a few end gashes and get into smaller holes. Have to clear the swarf often.