Lots of people have asked how to extract broken bolts on foil fuselages. Here's the bottom line--if you broke a bolt while tightening it, any advice about screw extractors and the like comes from people who have never done this shit. If you break a bolt loosening it at least the threads are not jammed tight against the thread faces. But most bolts get broken during tightening, and you can't loosen them with some device that applies less torque than the original bolt head. Period. No, not going to happen. So you need to drill out the bolt leaving a thin shell with the threads intact so you can make the threads and the remaining thin shell of the bolt collapse (generally with a chisel and hammer), and take it out. Or you can weld a nut onto the threads and turn it out. The problem with welding a nut onto stainless bolts is that you need to spill argon everywhere to get a decent weld. No way to back purge the stainless so you just gotta blow argon everywhere.
If you choose to drill out the bolt, then that takes precision drilling, and that means you need the right toys--I mean, tools.
Specifically, you either need 30 years of experience or an optical center punch. Optical center punches take less time to acquire and are fairly inexpensive. Once you have one your drilling precision increases hugely and you'll find yourself to be a drilling precision snob.
Here's how this works:
Grind the bolt flat--I used my belt grinder.
Locate dead center of the bolt optically. If you look at the picture of the optical element you'll see where I fucked up. I didn't grind the bolt completely flat, just enough to get a good flat area for the centerpunch. But then I centered the optics on the flat area and skewed it a little towards the flat segment instead of taking the full bolt size center.
Swap the centerpunch for the optical element and whack the centerpunch with a hammer.
Presto, dead center--sort of. It's not the tools fault--it's the nut behind the wheel. I drilled this out but the threads were kind of rough and skewed a bit after I picked out the old threads. So I drilled it to 21/64ths and ran a Helicoil tap through to see how it looked. The threads were clean and full depth, so I ran in an 8mm Helicoil coated with red locktite, the remaining options would have been a 3/8ths Timesert or tig welding the hole up and re-tapping to 8mm, but the 8mm Helicoil worked fine. I fucking hate Helicoils, but they work and I have lots of them.
It helps to have a hard rock playlist running while you do this. Heavy Metal or 90's thrash goes well with metal work. I put on Skating Polly when I'm welding aluminum. Tradition.
If you choose to drill out the bolt, then that takes precision drilling, and that means you need the right toys--I mean, tools.
Specifically, you either need 30 years of experience or an optical center punch. Optical center punches take less time to acquire and are fairly inexpensive. Once you have one your drilling precision increases hugely and you'll find yourself to be a drilling precision snob.
Here's how this works:
Grind the bolt flat--I used my belt grinder.
Locate dead center of the bolt optically. If you look at the picture of the optical element you'll see where I fucked up. I didn't grind the bolt completely flat, just enough to get a good flat area for the centerpunch. But then I centered the optics on the flat area and skewed it a little towards the flat segment instead of taking the full bolt size center.
Swap the centerpunch for the optical element and whack the centerpunch with a hammer.
Presto, dead center--sort of. It's not the tools fault--it's the nut behind the wheel. I drilled this out but the threads were kind of rough and skewed a bit after I picked out the old threads. So I drilled it to 21/64ths and ran a Helicoil tap through to see how it looked. The threads were clean and full depth, so I ran in an 8mm Helicoil coated with red locktite, the remaining options would have been a 3/8ths Timesert or tig welding the hole up and re-tapping to 8mm, but the 8mm Helicoil worked fine. I fucking hate Helicoils, but they work and I have lots of them.
It helps to have a hard rock playlist running while you do this. Heavy Metal or 90's thrash goes well with metal work. I put on Skating Polly when I'm welding aluminum. Tradition.