Even if the tap is tilted very slightly, it can break off in the drill hole. With luck, the break point is a little above the hole and can be "gripped" mechanically. If the tap is broken below the drill edge, it will be difficult.
A broken tap that protrudes upwards can be gripped with precision mechanics pliers. The remainder of the drill is then turned out millimeter by millimeter against the direction of the thread. It is important to proceed carefully, as the tangible drill break point protruding upwards is often machined and easily torn off.
- Also Read - Regrinding a Tap
- Also Read - Correctly Cutting a Thread
- Also read - Cutting a thread with the lathe chisel - the basics
If the broken tap offers a volume point that can be reached from above, a center punch can help. A small center mark is placed on the thickest part of the material. The tap is slowly knocked out with light hammer blows on the center punch or a small pointed chisel.
If the break consists of a closed surface, grinding in a groove is an option. This then serves as a screw slot and the broken tap can be removed with a screwdriver.
A tap has longitudinal grooves. The special tool, the threaded crown, takes advantage of this. It can be inserted into the borehole from above with the prongs engaging in the grooves. "Fitting" can be supported with light hammer blows. After turning back and forth several times, the broken tap loosens and can be unscrewed.
Boring and eroding
The broken tap can be drilled out with a smaller drill. It should just about reach the inner thread path edges. Before drilling, set the direction of rotation of the drill (€ 48.00 at Amazon *) against the direction of the tap.
Metal processing companies can loosen broken taps by means of eroding in special machines. This procedure is particularly recommended for very small taps in high-quality workpieces.Tips & Tricks With a stand drilling machine and secure fixation of the workpiece, the risk of tilting is minimal. If possible, you should only use taps in this way.