need some help!!!

[cute_dorkie]

ok i dont know if this is where to post this!! i need help with a broken bolt and broken bolt extractor!! its on a cylinder head and the bolt broke about 1/4 or less below the hole...i bought a bolt extractor and drilled a hole and used the extractor and it was turning fine then crack it broke...now i dont know what else to use to get it out...someone i was talking to said to use a cobalt drill bit or a left handed drill bit...so dont know what else to do and dont know what kind of colbolt drill bit is the best for what i want to do...thanks for anyone who replies and whoever has any suggestions on what do do.

[Pandinus]

Do you have access to a welder???
Drop a thin copper tube or aluminum to protect the threads .. or be very careful/use tig... build up some metal till above the surface then drop a nut over the build up and weld the nut and crank it out... or use the buildup to remove the extractor and use a fresh one.

[cute_dorkie]

thanks for the reply and yes i do have a welder...i have a mig welder but the hole is kinda small the bolt that broke off is an 8mm bolt and the head is aluminum...i've been searching google to see if i could find some forums or someone who has had the same problem as me but no luck with that...thanks for the reply pandinus

[M250cnc]

cute_dorkie,

You only have two choices

One is EDM

The other is a stellite drill, now that you have broken a hardened screw extractor in the hole.

To use the stellite drill i suggest you have a drill guide made to stop the wander, which will occur if you use a drill press or maybe even a mill.

Once you have got the size to the screw core diameter, you then need to pick the remaining thread out with a hardened scriber for a turn or two, then use a tap to clean the rest out.

IMHO screw extractors are a complete waste of time, unless the thread is loose, but then you wouldn't have broken the stud to begin with.

Phil