Has anyone successfully drilled out an exhaust stud?

[Seeker 77]

If so what kind of drill bit did you use? I keep breaking HSS bits! Do I need to remove the head to do it?

[bigtwinthing]

I've probably done about 40 over the years. Centre punch, then a small drill. drill a small depth about 2mm and check its central. then drill with a fast speed but cool it with a bit of grease. last drill needs to be just smaller than the bolt/stud that was in it. i.e. if it was a 8mm stud drill the last size 6.5 mm as the thread itself may well be 1.5mm. The grease also helps pull the swarf off. You can check in a "Zuess" book it will tell you exactly. remember an 8mm bolt is probably only 6.2 mm as the thread adds the last bit to give the 8mm dia etc.

Its the initial start thats important. use the centre punch and make sure its in the centre. Angle and tap across if it isn't. It does work.

Ive taken out 4mm studs up to 20mm this way. The small ones are actually harder. OH and use a shape drill, which in itself is a skilful task to sharpen. As an engineer anybody coming for a job interview with me had to be able to sharpen a drill.

[Seeker 77]

Thanks mate, now can anyone translate the post above into non-Engineer? ;)

I'm not sure what a shape drill is, I have a bog stock DeWalt drill from Screwfix!

[simo]

Sharp drill. Is your stud broken off flush? If it still pertrudes have a nut welded on. The heat will also help removal.

[Watty]

Sharp drill. Is your stud broken off flush? If it still pertrudes have a nut welded on. The heat will also help removal.

Great northeast minds think alike! But I appreciate not everyone has access to a welder!

[adyf]

I might get corrected on this but is a cobalt drill better for this at a steady speed

[bigtwinthing]

I might get corrected on this but is a cobalt drill better for this at a steady speed

yep they are meant to be good. Providing an HSS drill is sharp it should be ok. Not one that some twot has drilled into bricks or a wall first.

By a small HSS drill bit from a tool supplier they are cheap for maybe a couple. Dormer are a great make. Its really about keeping even pressure, drilling straight and not bending the drill bit. start small, get bigger each time. let the drill do the work and done force it, you will overheat the drill bit.

Be careful drilling s/s it work hardens, if you relax off any pressure, you then can't drill through it. if the stud end is showing and you can't weld, but the bolt has sheared at a funny angle, file or tap it flat to start.

[tony.mon]

All of the above, plus, if you or someone else has snapped off a broken stud extractor in the stud, give up and let a professional at it......

[bigtwinthing]

All of the above, plus, if you or someone else has snapped off a broken stud extractor in the stud, give up and let a professional at it......

after that, its "Spark Eroding "

[tony.mon]

Not worth it, after that it's spare head.

[bigtwinthing]

Not worth it, after that it's spare head.

I know but can i get commission suggesting you still have some spare

[tony.mon]

Oh, yes, I have a pair of spare heads, but they're something a bit special. ..

[Varastorm]

The best solution I have found is left handed fluted drills.

Similar method to what has been mentioned above. As you increase the drill size it heats up the stud & more often than not the drill bit will grip the stud & unscrew it.

An accurate first hole is the key, if the initial hole is off centre, the possibility of cutting into the softer aluminium will rear its head as you increase the drill diameter. All's not lost if you do, you'll just have to try & collapse the stud in the hole then, pita, but still possible.

Cutting fluid is a must to keep a keen edge on the drill bits.

Good instructions in the add, but beware of snapping any drills or extractors of any kind in the hole = BIG TROUBLE

http://www.ebay.co.uk/itm/Left-Hand-Spi ... Sw9r1WC7ry

[AMCQ46]

never knew you could get left handed drills........ every day is a school day .. well not this week as its school holidays, but you know what I mean

[cheekykev]

This left handed drill thing has been mentioned before, I'm an engineer, trust me you don't have to go to the trouble of getting left handed drills, just use normal drills and re- grind the cutting edge and rake angle the opposite way, It's quite easy, I've done it loads of times, if you don't feel confident about doing it I'm sure you'll know someone who can do it for you, all you need is a bench grinder.
Plus as mentioned above, you might fall lucky and the drill might grip and run the stud out.