Posted by peter ferro on October 20, 1997 at 01:15:32:

In Reply to: Re: Topic: Drilling and Tapping posted by Heath Satow on September 06, 1997 at 18:38:13:

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: : Tapping is a simple machining operation that many people overlook either because we have broken a tap in a hole once and couldn't remove it (happens to all of us at one time or other), or because it's simply a mystery. Well, it isn't a mystery and if you've had a broken tap remain in a hole and couldn't remove it, well it's just a tough apples kind of thing and we have to move on with our lives. --snip--

: :Chris Ray

: I'm one of those people that occasionally breaks a tap in a hole (who hasn't?) and this is how I've dealt with it when tap-removal tools don't work.

: Since taps are the hardest substance known to man, much harder even than diamond --grin--, drilling out a tap is virtually impossible. The only thing left to do is destroy the tap that is left in there.

: I usually use my plasma cutter to blast out that area where the tap is, and fill weld the area. Grind flush and start over. Don't quench the area, or you may harden the area and ruin your drill bit, and have to start over again. Let the piece air-cool, re-drill and tap more carefully next time.

: PS, I've found the best lubricant for drilling and tapping stainless steel to be good old water, better than any oil-based lube I've tried, but this is only for stainless.

: -Heath

: -antfarm

Because taps are still a steel , you can burn them out with the cutting torch. and if you are real good/careful you wont damage the already cut thread. This wont work on blind holes or really small taps . You can also heat the broken section red hot and punch it to the bottom of the hole. (ruff i know but it gets it out of the way]. Some times depending on the size and the way it broke you have to make a special tool which fits the flutes and turn it back the way it came.A little heat helps where appropriate to soften the chips on the cutting edges to get the broken part to move.

I find lard the best cutting compound for the hobby workshop. But dont let it go rancid though.Thought I had a dead rat in the shed but t was some long dead lard.

(A little bit of alliteration to finish)

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