these chinese made brittle pieces of **** must be the hardest substance on the earth.i bought the best bit home depot had to offer. cobalt, hardened. all it did was skid across the surface. no bite whatsoever.then i decided,since i was going to drill it(exhaust manifold bolt)out a size larger, that id just take the smallest bits i had(1/16)and drill around the stuck bolt.this didnt work out so well, i boogered it up a bit. may most a pic, its .so i took an ancient sears made dremel-like tool and a grinding stone, and went at it. at least this has made a dent. but, in doing so.... i burnt up my tool. put the bit on the drill and continued. i finally hit a wall, where im not making progress anymore. need a new bit.this stupid bolt is costing me more than id like. but, i cant stop now. i did some reading online, and came across a thread about drilling through hardened steel. they were discussing the use of masonary bits,and a lubricant...at a slow speed. they claim it works like a charm. i got to looking at carbide tipped bits, and they are similar to a masonary bit(at least one design).so, im going to give a masonary bit a try before springing for a carbide tipped bit.

 

Moved this to the tool section ya tool...J/K

 

heh,thanks

 

so your trying to drill this out? (the extractor) or what?

 

If you got an extractor broken off in a hole of a bolt your in trouble. In most cases I would say to try to go at it with a torch and burn it out! Get it glowing hot and hit it with some oxygen. If you try to use carbide or cobalt bits you are only going to dull them out. If you can try to drill the bolt from the opposite side, then do this until you hit the extractor and then pound it out with a punch. Next time use the hot wrench on the manifold and get it glowing before installing the extractor! Best of luck. Vince

 

a carbide masonary bit worked. slow, lots of pressure, and lube. theres still a tiny bit of the extractor left, but i think i have plenty of room to tap it and put in a stud. thanks for taking a look.