On Thursday, March 31, 2016 at 7:27:02 AM UTC-7, Mr Macaw wrote:
These sound useful, ever used anything like this?
http://www.ebay.co.uk/itm/181742384239

Have a set from Snap-On, but have rarely use them. Usually, after drilling thru a busted bolt or whatever, the harden steel extractor breaks off making the problem way worse (time for a carbide bit)
The problem comes because the hole ya drilled went off center and into the structure, preventing the proper use of the tool.
Extracting busted bolts is an "art"
I'd suggest buying a set of "reverse" Cobalt drills.
These usually work if you drill straight down thur the "problem" (unless it's hopeless rusted in place)