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Old 06 September 2013, 14:00   #21
Country: UK - England
Town: Bristol
Make: Ribcraft
Length: 5m +
Engine: Yamaha
Join Date: May 2006
Posts: 4,235
Originally Posted by HighlandR View Post
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 !
I would personally get a stainless nut on both of them, the one on the right, screw it on till level then weld it on. then gently heat the alloy till pretty warm or as hot as ya dare with the occasional sharp tap with the banging stick to shock the stud into breaking its seal. hopefully it should unscrew,
same with the other one,again put the nut over the remains of the stud. weld down through the nut thread .... slightly less chance but i would give it a go.

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Old 06 September 2013, 15:07   #22
Country: UK - England
Town: Alton
Boat name: Douggie
Length: 4m +
Engine: 40 mariner
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If you have to resort to drilling use left handed drill bits, the last size normally grabs what's left and unwinds it.

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Old 06 September 2013, 17:29   #23
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Town: Principalite d'Chaos
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Make: Ocean & Bombard
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As has been said the easiest way to get them out is to weld a big nut over the top of them.

I've done it loads of times, the heating helps to break the bond, and you have a nice fresh un-rounded off nut of a bigger size to get purchase on.

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Old 06 September 2013, 17:47   #24
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Country: USA
Boat name: Uh...a kayak?
Length: 4m +
Join Date: Dec 2009
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The best trick is to stop BEFORE the bolt breaks and get heat and shock sent to the frozen bolt. Also rock the bolt both directions gently. If penetrating oil can get in, it will work wonders. When going back together use a little anti-sieze.

If it were in front of me I would use what I have at my disposal, which is a plasma cutter to gouge out the broken easy out, then hit it with lots of TIG heat, finally welding on a couple of nuts, and of course an impact air hammer with a point bit will break the crud.

FWIW this style of bolt extractors do work very well. I have three different extractor kits for bolts, along with other type of fastener extractors, and have never broken one yet.
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Old 06 September 2013, 19:24   #25
Country: UK - England
Town: Liverpool
Length: 6m +
Join Date: Jun 2013
Posts: 153
Another tip if you can get the casing off in your hand is to clamp the protruding stud in a decent vice, you'll grip it better than mostly anything else will and with a little heat you've a chance with the longer of the two.

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