drilling a broken stud..how do i center the drill

[steveo3002]

ive got a couple of broken studs to tackle..hoping i can weld something on em and get em out

if i need to drill them , I'm not too hopefull on getting the drill dead center

any suggestions /tips on getting the drill bang on the center?

[pauldaf44]

center punch and a hammer

[rtlkyuubi]

use a centre punch to indent the stud for the tip of the drill bit to sit in.

[steveo3002]

just eyeball the punch though? one of em is a m6 so not much room for error

[berny]

my stepdad always used a reverse thread drill for snapped bolts, i thought he was winding me up the first time he suggested them to me ;D
i think screwfix or machine mart do them?

[steveo3002]

yeah got some of them ..i still want to make the pilot hole central as possible

[elmotheewokking]

You can measure and mark where to put the centre punch if you're that worried about it, but as long as you can hold the drill straight, you'll be fine.
Use a pillar drill if you can.
What are the studs stuck in?

[steveo3002]

its an exhaust manifold ...plus I'm expecting a head stud or two to snap when i remove the manifold

[ruishy1]

grind the head flat and centre punch, about the best things you can do

[v8ian]

Put the manifold back on, find a drill that is the bolt clearnce size in the manifold and spot drill the top of the stud thru the manifold using it as a driling giude, once spotted, remove the manifold and drill the stud a size less than the tapping size

[donttellhimpike]

centrepunch and start with a tiny drillbit [2mm] only a bit

[suterman]

Whatever you do, don't overheat the job, I did that once, overrevved the drill and it turned red hot and cooled down again, melted the end of the drillbit and kind of hardened the stud, (at least thats what I think happened) after that it took me all weekend to drill out using the best drill bits I could find. (use low speeds and oil or water to keep it cool)

It was a turbine housing/downpipe stud so it was pretty hard to start with.