Broke a Tap while Threading new hole

[Furu]

Well I have done it now.

I was using a 10-24 thread tap to tap a new hole in A-36 steel and broke the tap.
Yes I was using cutting oil and backing off as I proceeded to cut the threads but it happened anyway.

What I have above the level of the hole is about an 1/8 inch length of 1/3 of the diameter shard of the sheared tap. With the three flutes on the tap it broke leaving only part of the shaft above hole level. I have tried to get it out but have been afraid to break off the remaining shard and making it worse. With the tap being hardened steel I doubt that I can drill it and put a screw extractor on it. I know that heat will loosen a stuck bolt but don't know if hardened steel expands faster or slower than the mild steel around it. Thought that heat might soften the tap and then I could drill it for a really small screw extractor.

While I am certain that no one else has ever snapped a tap I figured that someone could give me a good technique/idea as to how best proceed.
My last broken tap was over 20 years ago and thus my lack of anymore ideas on how to proceed.

 

[2458n]

Get a flat washer and place over the tap that is sticking out. Weld the washer to the remaining piece of tap. Put a nut over this and weld to the washer. Take out with a wrench.

 

[CNC Dan]

Get a flat washer and place over the tap that is sticking out. Weld the washer to the remaining piece of tap. Put a nut over this and weld to the washer. Take out with a wrench.

What he said.

 

[mikehaugen]

They sell special "tap extractors" that have 4 prongs to fit around the tap in the hole. I personally have never had good luck with them because usually a broken tap is lodged in too tight to begin with. They would probably work okay if the tap broke because it got hit with something (and the remaing piece was loose in the hole) but that is rarely the case. Still though, it may be worth a try. It depends how much it's worth to you, as they aren't cheap I don't think.

 

[Tor Arne]

If the hole goes through the part you are working With? It has happened that I have been using a punch and beaten the tap out. Since it is mild steel that can weld the hole and start over or drill up and use a larger screw or Helicoil

 

[timster2]

If you have the equipment here is a good video on broken tap removal Remove a Broken Tap, Exhaust Stud, or Pressed Pin with TIG welder - YouTube

 

[boggen]

all i can say, is best of luck.

 

[Buckgnarly]

I have a whole set of these...as said earlier, they work OK if the tap is not too stuck. Go easy and maybe buy some extra fingers for the remover...

Walton 10103 #10, 3 Flute Tap Extractor With Square Shank: Threading Tap Extractors: Amazon.com: Industrial & Scientific

Walton 10103 #10, 3 Flute Tap Extractor With Square Shank: Threading Tap Extractors: Amazon.com: Industrial & Scientific


Walton Replacement Finger for 4 Flute Tap Extractor, #10 Size: Threading Tap Extractors: Amazon.com: Industrial & Scientific

 

[SPYDERLK]

Well I have done it now.

I was using a 10-24 thread tap to tap a new hole in A-36 steel and broke the tap.
Yes I was using cutting oil and backing off as I proceeded to cut the threads but it happened anyway.

What I have above the level of the hole is about an 1/8 inch length of 1/3 of the diameter shard of the sheared tap. With the three flutes on the tap it broke leaving only part of the shaft above hole level. I have tried to get it out but have been afraid to break off the remaining shard and making it worse. With the tap being hardened steel I doubt that I can drill it and put a screw extractor on it. I know that heat will loosen a stuck bolt but don't know if hardened steel expands faster or slower than the mild steel around it. Thought that heat might soften the tap and then I could drill it for a really small screw extractor.

While I am certain that no one else has ever snapped a tap I figured that someone could give me a good technique/idea as to how best proceed.
My last broken tap was over 20 years ago and thus my lack of anymore ideas on how to proceed.

Some considerations that could be important: How deep had you tapped before breakage. Did the tap break by twisting, or did you accidently jog sideways and break it. What was the last twist motion [in or out] before it broke?

... If the tap is not in deep you can probably loosen it by tapping using a "soft" punch made from a nail. Stay away from the shard at first. Put some penetrant down the hole and blow it out thouroughly to clean out any chips. Then tap straight down, then at angles alternately. Then tap gently back and forth on/near the root of the shard - first in the opposite direction you were going when it broke. - Repeat. - If it moves youve got it beat ... just be patient as you do back and forth motion.
Good luck!
larry

 

[Brant]

I have had good success with welding a nut onto the broken tap.

 

[pmsmechanic]

I've had good luck with beating the tap out as Tor Arne suggested. I usually just use a helicoil but I have just tapped the resulting hole with a new tap and called it good. I can see welding work also. The only thing I can add is that once your done welding just take some wax and let the heat from the weld melt it into the hole. Wax works awesome as a penetrating fluid.

 

[SPIKER]

10-24 is pretty small for welding nut on unless you have heli-arch/tig welder. so far there are 3 good suggestions I've had some luck with all of those methods.

One thing is to make sure you are using correct size drill bit, make sure you have only slightly more depth of metal than 3 full thread lengths of the size. So for 10-24 tapping more than 1/4" thickness is a waste. if you were tapping a piece of 1/2" plate drill it all way thru and open the hole up halfway with a #21 drill bit in stead of the #25 so that you are not using full length of tap in the tight hole...

 

[930ck]

Was able to drill out a broken tap by heating it up with a torch cherry red so the tap was annealed, let it cool and then drilled it out.

 

[Mendonsy]

10-24 is pretty small for welding nut on unless you have heli-arch/tig welder. so far there are 3 good suggestions I've had some luck with all of those methods.

One thing is to make sure you are using correct size drill bit, make sure you have only slightly more depth of metal than 3 full thread lengths of the size. So for 10-24 tapping more than 1/4" thickness is a waste. if you were tapping a piece of 1/2" plate drill it all way thru and open the hole up halfway with a #21 drill bit in stead of the #25 so that you are not using full length of tap in the tight hole...

YEP!! Generally all that you need for thread depth is the diameter of the fastener. Anything more than that is excess.

 

[300UGUY]

Rule of thumb we always used was 1.5 x nominal diameter for thread engagement.