Cheers. So according to my 'research', the thread is 1/8 BSP - I don't have any left hand bits, so I'll need to get some. What would be the right size to drill this out please? Don't want to buy the wrong thing.
You do get left hand bits. The flutes are in reverse so that when you drill in the reverse direction, the material is removed. Using a normal bit in reverse is going to force the crap into the hole, which is what I'm trying to avoid.
If you are going to tap a 1/8 BSP thread you need to drill the hole to 8.8mm.
Thanks. I'm not goint to tap a thread - there is already one there, I'm just going to drill down the existing thread. As the bolt has a very thin wall, I'm hoping it will disintegrate whilst I drill and leave the thread intact.
Probably best practice to run a tap down the thread to clean it up anyway or you may end up back in the same situation.
Probably best practice to run a tap down the thread to clean it up anyway or you may end up back in the same situation.
We're not still talking about his helmet are we?
I've got a set of Sealey easy outs in my tool box but I've never used them so can't say if they're any good. If you try an easy out I'd recommend to hit the stub of the banjo bolt and the surrounding area with a hammer to put some shock through it.
Just another idea to throw into the mix. You could drill the hole out part of the way through say with an 8mm bit. Then us a chisel around the bolt to collapse it in then try a small pair of mole grips. I've done this on exhaust manifold threads before.
Picked up a clark screw extactor kit this moning on the way to work, so I'll have a go with it tomorrow. Any tips on how much resistance I should feel? I presume it should feel like when you're tapping a hole. My plan is to not try any drilling and just go with a size that will fit down the existing bolt.
I have some easy outs. They just tighten in, go slowly, then when they are tighter than the offending part will start to wind it out. Go by hand and judge it, as if you snap the easy out they are almost impossible to drill.
The bolts aren't to long, maybe the threaded bit is 10mm maybe? Want me to whip one of mine out and measure?
Hopefully if you felt it move a bit it should wind out ok, shock and penetrating oil the #### out of it before hand though