How To Use A Screw Extractor
what you'll need:
A screw extractor is actually two different parts working together: a screw extractor bit and a tap wrench. Screw extractor bits look like normal drill bits, except that they're roughly pyramid-shaped -- the tips are pointy, and they flare wider towards the base. The base has a square protuberance, which fits into the tap wrench. The interesting part about the screw
extractor bit is that the threads on them run "backwards", or counterclockwise (drill bit threads run clockwise). You'll you use a normal drill bit to drill a hole in the bolt, and the push the corresponding screw extractor bit in -- the counterclockwise action used to screw the extractor bit into the hole will be the same counterclockwise action normally used to remove a bolt.
Here's a picture of the drill/extractor bits kit that I have. It includes five drill bits, and the corresponding five screw extractors. The drill bits are on the left side of the case; the screw extractors on the right.
Before You Start:
Lets Get Started:
covering for it. The Nighthawk's broken bolt was one of the cylinder head cover bolts, so I had to remove the cover to get to the broken bolt. That meant we were drilling right next to exposed valves and camshafts. We taped a few layers of duct tape over the end of the cylinder head (cutting a hole for the bolt), and attached a folded-over paper towel to catch any stray shavings.
Now you're ready to drill. Put on your happy eye protection, attach the correct size drill bit, line it up smack dab in the centre of that stuck bolt, and drill. You don't need to drill all the way through the bolt; halfway through or less should suffice. Remember that you don't want to damage any non-bolt part of the bike, so it's much better to drill too little at first and then go back and drill more than it is to be over-enthusiastic and break something. If you're in a metal shavings sensitive area, you might find it helpful to have a friend hold the tube end of a vacuum cleaner nearby to suck away stray fillings while you're drilling.
Once your hole is drilled, attach the corresponding screw extractor bit into your tap wrench. Simply insert the tip of the extractor bit into the hole that you just drilled, and turn counterclockwise. Since the threads are reversed on the extractor bit, turning it counterclockwise will tighten the bit into the hole in the bolt. The tapering on the bit means that it will eventually fit snugly within the broken bolt, at which point, turning the bit counterclockwise will force the bolt to turn counterclockwise as well. As we know with bolts, it's "right to tighten, and left to loosen", and turning a bolt counterclockwise will remove it.
The bolt should now come out, and you're as happy as a pig in shit.
|Now you can go re-order that stupid bike-specific bolt for ten quid from the local dealer (and probably wait another two weeks while the ship it from some obscure country :-) )