Best way to remove broken tap

[captlloyd]

Originally Posted by missourisailor

Several assumptions here.
The cutter is off the shaft.
It is a through hole.
You don't have much more than 1/4" of the tap, in the hole.


Using a needle tip rose bud torch head, heat the tap to cherry red.
Using a straight, pin punch, just smaller than the minor dia of the hole. beat the snot out of the tap until it is driven out.


After everything has cooled, enlarge the hole to accommodate a heli-coil. Thread and install the heli-coil. Then install a new set screw.



A through hole is easy to fix. A blind hole is a PITA!!!!!

Assuming the part is off of the shaft, this is a excellent idea ! Better even than a plasma cutter.

[Taipe]

Have you already removed the line cutter from the shaft?

[missourisailor]

Originally Posted by captlloyd

Assuming the part is off of the shaft, this is a excellent idea ! Better even than a plasma cutter.

The problem with a Plasma cutter, EDM, Arc-gouge..etc, is they all can and will cut SS.
A flame, with only a few exceptions, can not cut SS.

So it is possible, if you are good with a torch, to melt out a broken HSS and/or carbide tap from a SS part. Without harming the remaining threads.

[Ziggy]

Originally Posted by Dave_S

I've never tried acid, let us know how it goes.

Success!!


I submerged it in battery acid (sulfuric acid) diluted 2:1 (so maybe 15%-20% ?). After a week the tap was completely dissolved. The 316L line cutter appears to be intact, although the finish turned slightly black in places.


I still may need to use a tap to clean out the thread, although the acid may have done it for me. As I recall I used some sort of lubricant the first time although I'm pretty sure it was not "official" cutting oil.



Thank you all for the advice and moral support!