How to extract a broken tap

[Vikash]

I drilled and tapped 32 holes in 8 heatsinks earlier today, and snapped the tap with just 2 holes to go

The tap is M3 size, and there's nothing protruding to grip 'n turn. Any ideas how I can get this tap out without damaging the thread?

[jaycee]

If you have a drill press, try and drill it out. Thats about the only thing you can do.

[Conrad Hoffman]

I hate it when that happens If there is nothing protruding, you can either open up the material around the tap with a small burr in a hand grinder (MotoTool), or drill a larger hole in from the opposite side to grab it. My guess is neither of those solutions will do for you. There are shops with EDM equipment that will burn it out for you with no damage to the aluminum, but it may cost more than the heatsink is worth. People do that with really expensive stuff. Sometimes a person with a small arc welder can spot a piece of rod to the top of the tap to turn it out. There are also small tools available from machine shop suppliers that have two or three fingers that go down the flutes and allow you to turn it out, but if the tap is tight I question how successful that method will be. Sometimes tapping the top of the tap with a small flat punch and hammer will loosen it up (add some lube obviously), allowing the less damaging methods to have a chance at working. Finally, the classic method is to drill around it, remove the thing, then ream the hole to a larger size and press fit an aluminum plug in place, followed by redrilling and retapping. Whew!

[BWRX]

Originally posted by jaycee
If you have a drill press, try and drill it out. Thats about the only thing you can do.

This works well with screws, but a tap is usually made of a harder material... Screws usually crumble and fall apart if you drill them. I don't think a tap would do the same thing. Taking your work to a machine shop would be your best bet if you want to salvage it. They've usually done this sort of thing many times before.

[chipco3434]

Ugly, but it works if there's a tiny bit still above the surface or if it's flush.

Use a nailset or a sharp punch. Use the punch and a small hammer to tap on the flutes to unscrew the tap. Patience. Just keep tapping on the broken tap, it will unscrew.

Next time use a two flute tap. They're stronger and less likely to bind.

[chipco3434]

or this...

http://www.newmantools.com/waltap.jpg

[Peter Daniel]

Originally posted by Vikash
The tap is M3 size, and there's nothing protruding to grip 'n turn.

Even if it's protruding, it will break when you try to turn it. Drilling it out is out of the question, it always slips and you drill aluminum.

You may try what chipco3434 is suggesting, although I never did it myself either. When I break the tap, I almost always make a new hole.

More info here: Removing a broken tap!

[405man]

I broke a tap while trying to remove a broken stud from an alloy cylinder head on the car. As the taps are hardened you can not drill them out. I took it to a local firm who used a spark erosion machine to remove the broken bit. The process cut a cylindrical hole around the tap which was then removed, they said they did work for a local aero engine manufacturer and had removed many broken taps from various exotic materials

Stuart

[Nordic]

Damn I threw the flier away, was recent, RS components sell a broken tap remover kit thingy... Think its like taperd drillbits to prevent it getting stuck maybe call their help no?...

I would take Peter Daniel's word as fact. He is a metal master!!!!
Thanks for teaching me how to cut aluminium on my tablesaw.

[jacco vermeulen]

One way is to make the heatsink really hot, then very rapidly cool it off.
Aluminium has a thermal expansion ratio almost twice that of steel, but is much softer.
The threaded hole in the heatsink is molded around the expanded tap end by heating and cooling the heatsink successively. A trick my dad tought me, i'm an ex tap-remover child slave.

May terminate the anodising though, and not for cyl-heads.