I saw a hot rod once and the guy
Had drilled tiny holes through the head of the bolts on stuff.
Then
He threaded some high tensile (tiny) wire through the holes in the bolt holes.

It was supposed to stop the bolt from backing out.

Thanks in advance.

It's called safety or lock wire. It is required on all critical parts in aircraft.

There are other ways to do it in automotive. I'm guessing this guy did it for the look rather than function.



You can't just do it either, there is a very specific way it has to be done.

Before Loctite, they needed a solution for the Oompa not spitting out the bolts. Internal combustion is the OG impact un-driver.

Safety wire still required in lots of things, aviation, car and motorcycle racing etc. Loctite or special locking washers etc. is NOT a substitute normally since there is no way to confirm the situation. I've safety wired perhaps a zillion bolts because I've raced things since time began and there is little more satisfying than a job well done. Special pliers are normally used to do it and make the nice twists. The above picture would normally flunk an inspection because of the hanging tail but it otherwise a good example of the direction you need to go to prevent loosening.

Safety wire is not used on production automobiles. Some nuts used on, for example, steering linkage parts are castellated for a cotter key/pin to go through, but lock nuts of various types are more common these days.

in the firearms world it is called Lacing Wire, and some MG's (the early M60 for example) used it as well,

Dad was a Small Arms guy for an AMSA unit, he would have to inspect etc a Units weapons and was pretty damn fast with the lacing wire and shears to do it with,


that stopped sometime in the 80's IIRC

quote:

Originally posted by arcwelder:
Before Loctite, they needed a solution for the Oompa not spitting out the bolts. Internal combustion is the OG impact un-driver.

Also, for aircraft mainly, back-out resistant metal screws with threads that were purposely kind of malformed.

Also called it “mousing” , “safety wire” & “lock wire” in the service. We had to safety wire a bunch of bolts in the machine guns and cannons…even the M60 had the bolt to the gas assembly lock wired. But the 20mm Olerikon cannon was the worst for it.

We used to joke about sacrificing blood to the lock wire gods

quote:

Also for aircraft mainly, back-out resistant metal screws with threads that were purposely kind of malformed.

Also called K nuts or jetnuts. Part number 21042-6 for a 3/8 thread size. They are also two wrench sizes smaller than the regular size would be for that thread. For example a 5/16 bolt would normally use a 1/2 hex/wrench size but the K nut is 3/8. They can go in smaller spaces and are lighter for applications where weight is critical an money less so.

https://fsaeparts.com/products...42?variant=596232861

Safety wire is more for bolts that don't have a nut on the backside.
Another method is to use a metal locking tab that gets bent up against a flat on the bolt heat.
At the end of the safety wire process it's advisable to bend the last 1/4" or so over onto itself so it doesn't leave a sharp end exposed. The photo above shows it as an amateur would do, leaving a raw end sticking out that will make a painful cut on anyone that works near it. The diagram the correct way with the end bent over.

I've had my safety wire pliers since I got them in the Army back in '75.
Used to use them all the time and when I got out they just happened to end up in my personal stuff.
Over the years I've done alot of equipment that needed them.
They sat for a long time, but now I've actually found that I'm using them more.

I haven't used my safety wire pliers for quite a while now, but I know exactly where they are located.

As an USAF aircraft electrician in the 70's, my fingers and hands had many holes poked in them by safety wire.

I am guessing that the bolts come with the holes pre drilled ?

quote:

Originally posted by bendable:
I am guessing that the bolts come with the holes pre drilled ?

Yes

Not necessarily. I had to drill all the bolts on my race bikes. I made jigs to guide the bits because I didn't have a drill press.

quote:

Originally posted by MikeinNC: But the 20mm Olerikon cannon was the worst for it.

We used to joke about sacrificing blood to the lock wire gods

Yep the m242 25mm bushmaster had them as well. I never had to change them though.

quote:

Originally posted by trapper189:
Not necessarily. I had to drill all the bolts on my race bikes. I made jigs to guide the bits because I didn't have a drill press.

Wow. Impressive.

In commercial applications that are mandated to be wired the bolts come pre drilled and are often of an specific specification think aviation. In other applications like motorcycle racing you have to drill them yourselves as the mfg. has no reason to predrill them for a consumer product. I know it sounds like a big deal but at least on motorcycles these are not hardened bolts and its extremely easy to drill them. When you are a beginner you might break a few bits and cuss a bit but having done maybe 50 motorcycles at this point in my life I can do one with just one or two bits. I always remove the bolt to do it, but I have seen people more experienced than me just grab a portable drill and do them on the bike!

Inboard ski boats have safety wire on rudder fasteners, and on prop shaft packing gland nut. I've done a few and have tie wire spinning pliers.