Removing Broke Taps

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Well-Known Member
Jan 9, 2004
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So, your tapping a hole and snap! it breaks off below the hole. That really sucks. I've had it happen a couple of times. But I found a new trick that gets them out, but it only works for non-ferrous metals. I got the trick from a machinist buddy. He told me go and buy some Alum (Aluminum sulphate) and dissolve a bunch in some boiling water. Don't do this in a metal pan, as it will eat it. I heated some water up in a plastic container in the microwave and dissolved as much Alum as I could into the water. Then I dropped my piece (forward closure) into the solution. Immediately the hole with the tap in it started fizzing. Cool. Then it stopped when the water cooled down. Not so Cool. Hmm.

I happened to be browsing a physics site that had some cool experiments. One was a bunch of neon lightbulbs in the microwave. Then there was aluminum foil in the microwave - and they said if it was in water it wouldn't spark and freak the microwave out. A lightbulb went on. Closure in soluition, solution in microwave, microwaving and it heats everything up and it keeps fizzing. Hmmmm. So I went outside to my 'shop' microwave (and old one from work that I got) and put everything in. Set her for a minute and let it go. ZZzzzzzzzzz. Bubble Bubble BUBBLES!!!! It was boiling the water no problem and no sparks. I set it for an hour and let it go on the porch. I came back and hour later and guess what? The tap was gone! Just like that. Easy as pie. I just buffed the aluminum back to a shine. I was happy!

Cool chemistry! You could have left the part sit in the Alum solution overnight and got the same effect. Heating keeps everything mixed and speeds up the process. The Alum salt converted the Iron in the tap to iron sulfate wich is soluble in water. Since the water is already saturated with aluminum sulfate the aluminum closure didn't dissolve. You could always put wax or paint over parts of the metal you don't want to expose to the salt solution.

Bruce S. Levison, NAR #69055