Broken Stainless Bolt Removal ??

HighlandR · 05 September 2013, 22:24

Hi guys, have 2 broken stainless steel bolts here that need removed from the aluminium casing.

1 bolt has some thread left on it ( a notch has been cut into the end of it for a screwdriver but part of it has broken off making the screwdriver method pretty useless )

The other bolt was drilled and a bolt extractor used which then snapped and is now stuck inside the bolt.

How can i remove these 2 bolts ??

Drill the extractor out with a tungsten or cobalt bit and use another bolt extractor or... ?

How is best to remove these without damaging the aluminium casing ?

The bolts are 6mm

Any help would be greatly appreciated !

SparkUK · 05 September 2013, 22:41

The one without a stud extractor will drill out but stainless is never easy.

Stud extractors are a pig to drill

Do you have a local engineer who can spark erode them out?

You might find the threads are a mess regardless of how you get them out so might need an insert or similar pitting in.

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Bigtalljv · 05 September 2013, 22:45

Throw it out and buy a new one!!

Seriously all my home attempts with the same thing ended badly same as you. A machinist I used removed some busted screws for me by TIG welding a bead on to the end of them The bead gives you something to grab on to and the heat makes the aluminum expand more than the stainless so it helps break them free. Know any good machinists or welders?

paintman · 05 September 2013, 23:40

Removed 4 from the bottom leg of mine. Very careful drilling down the center of the remains using progressively bigger bits then a grinding bit on a die grinder. Still finished up heli-coiling them.
Welding onto the stubs didn't help, they just sheared off flush. Bit of a surprise as that's worked for me in the past.

Nos4r2 · 06 September 2013, 00:02

This thread should be a sticky to stop people trying to use easy-outs.

The one with the broken extractor is NOT going to come out without drilling. Period. It's expanded the bolt into it, so it's now more stuck than it was.You're probably best to try drilling it out on a pillar drill, VERY slowly with a decent drill bit and lots of lube

The other one you might find a shedload of blowtorch heating/cooling/plusgas cycles might free it enough to get it out with molegrips.

Downhilldai · 06 September 2013, 01:08

Easy-outs are the work of the devil.

Downhilldai · 06 September 2013, 01:10

Always helps to give the bolt a bit of a touch with a hammer before trying to unscrew it from aluminium. This will hopefully free off the corrosive bond that forms between the ally and the steel/stainless bolt.

whisper · 06 September 2013, 01:11

So how do the pro's do it? A bit of heat too?

Downhilldai · 06 September 2013, 01:15

Oi, don't you believe what NoS & I are saying?

whisper · 06 September 2013, 01:18

No I was just asking how they do it in the trade

I've seen Nos in action with a broken bolt removal, very impressive

Downhilldai · 06 September 2013, 01:31

Depends how much of the bolt is left protruding. If there's enough to get a mole grips/stillson on then you're in with a chance, BUT it's pretty well fixed there for the head to shear in the first place, so it'll need a bit of help. Heat, tapping along the length of the stud with a hammer and plus gas are your friends here. Hopefully, with a bit of clockwise/anti-clockwise persuasion, it will free off. If not, then drilling out is the next step.

If drilling out, then the remaining stud needs to be ground flat and perpendicular to the shank of the bolt. It can then be accurately centre-popped and drilled out in increasing drill bit diameters, starting with 2-3mm, working slowly with plenty of lube/coolant. When you get to the stage where the drill bit diameter approaches the threads, you can try tapping a new thread into the remaining material. If this doesn't succeed then it's helicoil time.

Nos4r2 · 06 September 2013, 01:53

Quote:

Originally Posted by Downhilldai

Depends how much of the bolt is left protruding. If there's enough to get a mole grips/stillson on then you're in with a chance, BUT it's pretty well fixed there for the head to shear in the first place, so it'll need a bit of help. Heat, tapping along the length of the stud with a hammer and plus gas are your friends here. Hopefully, with a bit of clockwise/anti-clockwise persuasion, it will free off. If not, then drilling out is the next step.

If drilling out, then the remaining stud needs to be ground flat and perpendicular to the shank of the bolt. It can then be accurately centre-popped and drilled out in increasing drill bit diameters, starting with 2-3mm, working slowly with plenty of lube/coolant. When you get to the stage where the drill bit diameter approaches the threads, you can try tapping a new thread into the remaining material. If this doesn't succeed then it's helicoil time.

They're M6 threads according to the OP, so I'd grind it flat and do it in one pass in a pillar drill with a 5mm bit. You're not going to get a anything smaller to go into an easy-out without shearing.

Tip....once you're PAST the easy-out, try it with a hammer drill. Sometimes it'll shock the thread free once the pressure on the bolt from corrosion and easy-out is reduced. There's no point trying it before the easy-out is gone, it's locked in there tighter than a BBC presenter on remand til it's removed.

Squid Boat · 06 September 2013, 05:46

Any engineering shops in your area that do EDM...Electric Discharge Machining. You would have to bring them the part.

Cheers, Squid

biffer · 06 September 2013, 08:05

I can do them, I would weld a nut on them, the heat from the welding would loosen them up and spanner them off

camelgas · 06 September 2013, 08:13

I have always thought easy-outs should be renamed hard-outs ! , nothing easy about them, work of the devil as said.

Some good advice offered so far, but drilling is hard as the easy-out is hardened and you risk running off line and damaging the work. I get broken bolts all the time at work and would approach your job by welding nuts on to whats left, several heating and cooling cycles and light tappings with a small hammer ,then try unscrewing with a close fitting spanner on the nut. If this fails your back to drilling.
good luck and go slowly and carefully.

Lee argyle · 06 September 2013, 10:47

Quote:

Originally Posted by biffer

I can do them, I would weld a nut on them, the heat from the welding would loosen them up and spanner them off

+1

mechanic by trade and if theres any stud proud then tig / mig a nut on, job done 99% of the time.

HighlandR · 06 September 2013, 17:19

Thanks very much for all the replies here lads!
Theres a local welder that has mig/tig I'll go see him about welding nuts onto the studs,

Like you say Nos, this Easy out is well and truly in there, i worry the welded nut would just shear off without drilling first.

When the initial hole was drilled through the bolt - the drill went through the aluminium making a hole to the inside of the leg...( the new bolt will blank the hole off once it's fitted ) but i'm a little worried about drilling the easy out that shavings and swarf etc will fall down inside the leg. How can i prevent this ?

Or should i chance it with the welded nut first and see ?

The bolts hold on the handle ( 2 bolts either side of the leg ) - which is used for lifting / moving the engine around and the handle also has the throttle/ steering lever mounted to it.

I wonder if the handle would be strong enough with just the 1 bolt on that side? and leave the broken Easy out bolt in the other to remove the risk of getting swarf inside the leg and just leave it there to keep the hole plugged?

Hightower · 06 September 2013, 17:53

People that don't know what they're doing break easy-outs/stud extractors.

Hightower · 06 September 2013, 17:58

I wouldn't faff about trying to remove those studs. Drill em out and use a helicoil insert or drill and tap the next size up if possible. Looks like you have plenty of meat around those bosses. I think you'll have a problem drilling the easy-out as they are usually hardened high carbon steel so spark erosion might be your only option know.

Bigmuz7 · 06 September 2013, 18:11

Quote:

Originally Posted by Hightower

People that don't know what they're doing break easy-outs/stud extractors.

Theres something to be said in that .. I use them but only where appropriate, they are too brittle to put any real strain on them. Often I think people drill, then use them and whack a load of torque on them without doing the heating and cooling cycles mentioned earlier particularly with some loosening agent as DHD and Nos stated. The aluminium alloy oxidation bond with the bolt is particularly difficult to break, but .. it is porous which is why the WD40 or whatever, is effective.