Getting out a broken tap... a potential solution

[Tommy B]

I've see this topic on different forums, this one included. One method I've never seen before is the use of a prick punch to shatter the tap and then dig out the pieces. Yeah, you ruin the center punch aka prick punch, but maybe the work that you're saving is worth the $5.00 that it costs to replace the tip of your Starrett center punch. (A center punch tip is about the only thing that goes for less than $5.00 from Starratt btw.)

I've used this method before. Center punches are hard, hard enough to shatter the busted tap that's jammed in the hole. I center punch the jammed-in tap, and then daintily reverse out the shattered tap's pieces using a tweeker screwdriver. Taps are brittle, somewhat like glass because then must maintain their edge. This can be used to your advantage.

Anyone else have luck with this method? Anyone here willing to try this method out and report back your findings to the forum? It's worked for me.

[palenn]

I have done it this way with some success in the past. Another method that sometimes works with larger taps is using an oxy/fuel torch. Preheat the tap as if you were starting a cut and, at the right moment, give it the cutting oxygen to blow the tap out. Chase the threads to clean them.

[djr76]

I use this method on a regular basis, I like palenn's method also...I do something similar but with a Tig welder.

[cheetahcnc]

Originally Posted by palenn I have done it this way with some success in the past. Another method that sometimes works with larger taps is using an oxy/fuel torch. Preheat the tap as if you were starting a cut and, at the right moment, give it the cutting oxygen to blow the tap out. Chase the threads to clean them.

I'll have to try the flame wrench on a tap

[Jake E.]

I usually use a straight flute drill to the minor diameter of the threaded hole or one size smaller and slowly drill through the tap to clear it out. Works sometimes, but not all the time. OTher method is using a centercutting 4 or 5 flute endmill ( I use old ones that have been changed out of the machine) and "drill" through it. Sometimes, if on a thru hole, it will complete the tapping job (BONUS!).

[3illmesmart]

I've used a punch to shatter taps, and yes, ruined some punches in the process. Best results for me was with masonry drills. Spot with carbide center drill, then drill through core with carbide tipped masonry drill. If all goes well, you can take the cutting edges out in complete pieces. Works good on taps over 1/4".

[neilw20]

You can spark erode (EDM) at the minor diameter and just fish out the leftovers, if the job is valuable and you don't want to cause more damage.

[vpmachine]

I still have a scar on one finger from the "shrapnel wound" I got from pounding the tap w/center punch idea. The straight flute c-bide drill works best, but on larger taps(1/4"and up) that are not shattered, a good tig welder can build up a "glob" of weld on top of the broken tap and "vise grip" it out while it's still hot. I didn't believe it until I saw it done, now I do it all the time.

[palenn]

Originally Posted by vpmachine I still have a scar on one finger from the "shrapnel wound" I got from pounding the tap w/center punch idea. The straight flute c-bide drill works best, but on larger taps(1/4"and up) that are not shattered, a good tig welder can build up a "glob" of weld on top of the broken tap and "vise grip" it out while it's still hot. I didn't believe it until I saw it done, now I do it all the time.

Can you explain the ""vise grip" it out while it's still hot"? Wouldn't the tap be tighter from expansion while it's still hot? How do I get a vise grip on a glob of weld?

[vpmachine]

You start tig welding a small "ball" of steel in the center of the tap (it has to be near the surface of the part) and then letting it cool off for a second or two. Continue to add "ball" on top of "ball" until there is enough out of the hole to grab w/ vise grips. When you clamp the vise grips on (TIGHT) it deforms the hot metal into a flat,hot, glob of weld attached to the broken tap. Now comes the tricky part, you work it back and forth, similiar to tapping by hand, until it comes out.If it breaks off do it again, this works almost every time, as long as the tap is not shattered. Next time I do it, I'll post a youtube video, and add a link to this post.