What Type of Bit to Drill Rounded Bolt

b422063 · Crazy Courier Joined: 14 Oct 2014 Karma :

I'm looking to drill out a rounded bolt as I can't get a grinder to it. Is this the type of drill bit one uses, or is there a better/stronger type?

Don't want it to blunt after seconds of use.

stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

hi,
yup thats what you need, cobalt drill bits Thumbs Up

i have a set & they have NEVER failed me.
there are "better"(carbide?) drill bits available but would just be overkill.
you can usually get away with just buying 3 or 4 ie 3,5 & 7mm as an example.
remember to drill slowly, keep the bit cool & use some sort of cutting oil.
i normally use a cheap can of 3 in 1 oil aerosol from poundland, with the wee red straw. it cleans most of the swarf away, cools the bit & lubes it too.
i know i should go look for more suitable cutting oil, but can never remember where i put it lol.

cheers,
GAZ

Taught2BCauti... · World Chat Champion Joined: 12 Jan 2012 Karma :

I use a set of These . Use them like a drill, but in reverse. If you are lucky, they will dig-in and grip the bolt, and remove it.
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b422063 · Crazy Courier Joined: 14 Oct 2014 Karma :

Woo! Took about 30 seconds to drill out! Perfect! Smile

........................ · Spanner Monkey Joined: 15 Jan 2014 Karma :

kramdra · World Chat Champion Joined: 28 Oct 2010 Karma :

Its useful to have a 80grit and 600grit drill attachments for sharpening, only takes a couple of seconds - HSS wont blunt quickly unless your drilling harder metals/stainless or getting it too hot.

Toolstation/heller cobalt ones are good enough.

Carbide is overkill and because if its hardness, needs diamond abrasives/grinding wheel to sharpen and will chip easily. It will cut anything with ease Thumbs Up

Have a Dormer set.

Tauht2BCautious - that set is cheap carbon steel, probably made in china, unlikely to last more than 5 mins, but might do the job..