Denny , good idea i'll have to try that this year . we always have broken taps working on our families crushers sounds like very good advice . hope to see more from you , and hope all is well with you . good luck . willie
Hi Denny, I purchased a 66 impala with a broken tap tool inside the crankshaft pulley thread hole. I wonder if it is a good idea or possible to use your oxy-acet trick to remove the broken tap without damaging the crankshaft threaded end area. I have tried everyting I know how but no avail. I tried to weld a rod to the short stub which was broke off from the tool and that did not work. I tried to turn the broken staff with a vise crip and that didnot help. Thanks, Harry
Harry, there are tools called "tap extractors". These have a fluted shaft with spring steel fingers that fit in the shaft flutes and slide down the tap's flutes. A collar is slid down to contact the workpiece, it keeps the fingers from spreading. I have ocasionally had sucsess with one of these tools, but about as often, not.
You could try this method first, You might get luckey.
With Denny's method it is important that only the tap gets hot, so You should have pretty good acess so You can see what You are doing.
Well, I finally had occasion to try this trick out this weekend. I had an iron railing, and I was trying to tap the 1" solid newel for a finial. Well, I wound up breaking a 1/4-20 tap almost 1/4" under the surface, since the hole in the railing was about 3/8", and the railing was welded to the top of the newel. This left the tap too deep to grab, or weld something onto.
My first try, I had a relatively neutral flame, and there wasn't much cutting action to speak of.
Second attempt had a strongly oxidizing flame, and once the tap was getting yellow, I shut off the acetylene, and sparks were wildly flying out of the hole.
Within about 3 or 4 seconds, the sparking stopped, there was nothing in the hole glowing, and the tap was completely gone.
In its place, was some cutting slag, around the mouth of the hole. I ended up drilling and tapping with a larger size (on closer inspection, the finial actually had a 3/8 thread, but had a 1/4-20 insert), but it was clear to me that the original threads could have easily been saved.
All I can say is WOW. That was cool!