Log in

View Full Version : Micro-Explosions When Hitting Two (Unmodified, Off-The-Shelf) Hammers Together


Positron
November 11th, 2007, 06:42 PM
Hi All,

I was recently at a very large department store (WM) here in The States with a few friends, and I heard loud cracking noises coming from one of the aisles. No big deal I though, it's just my weird friends hitting hammers together for fun :rolleyes:. So the noise keeps happening for a while, then one of my friends comes running around the corner telling me that I've GOT to come see this.

So, my friend picks two normal-looking sledgehammers off the shelf, and smacks them together pretty hard head to head. Nothing really happens, other than the nice "TING!!!!" noise that is made when two hammers contact each other.

He tries a couple more times, hitting them together pretty damn hard, until a much louder and sharper "CRACK" was emitted, complete with a puff of smoke, acrid smell, and tiny burn spot on the hammer!! The noise was quite loud; about like a couple of toy "caps" going off.

The micro-explosions were hard to repeat, though we could make them happen one out of every three or four hits.

They were 2 or 3 pound sledges if I had to guess. Wooden handle. I can't remember much more about them, but I'll take a closer look when I'm there next.

What do ya'll think?

Thermiteisfun
November 11th, 2007, 08:05 PM
It sounds to me like you were forcing the metal to oxidize by shock.

nbk2000
November 11th, 2007, 09:17 PM
Was there a paint coating on the faces of the sledge heads? Perhaps the pressure of being compressed was reacting components in the paint with the oxide in the metal.

hereno
November 11th, 2007, 11:36 PM
If it has a coating of oil, its possibly a dieseling effect.

Barnacles
November 11th, 2007, 11:50 PM
Mythbusters did something on this "proving" that hammers cannot explode via this method. Although I did see one thing wrong with their method. See when they smashed the hammers together they used two rigid pieces of metals in place of human arms for swinging.

I think these arms didnt allow certain types of vibrations to occur that would normally happen with human arms doing the work. Maybe the elasticity of the human arm causes/allows some sort of resonance frequency effect that the non-flexing , nonbending metallic arms would/could negate.

jetz
November 12th, 2007, 02:51 AM
I’ve heard of some cheap Chinese hammers being coated with NC to protect them during transport and when hit to together they crack from the NC going off.

Positron
November 12th, 2007, 10:20 PM
There is a "minor detail" that I forgot to mention. Yes, there is a coating on the hammer faces. It's clear, maybe a bit yellowish. Very thin. Sorry for not mentioning this the first time around.

Sounds like NC lacquer could be the culprit!!

Anyhow, Shadow3910, this is an entirely different phenomenon than what the Mythbusters were dealing with. They were trying to shatter the steel through physical means. What I witnessed involved a chemical reaction (forces within the molecule), as evidenced by the smoke and burn spot. I think the Mythbusters had the right idea with what they were trying to do, as elasticity in the system (human arm & body) would serve to dampen the mechanical resonances, and reduce the time-averaged internal forces across the steel. In the end, they were going for worst-case to bust the hammers. End Off-Topic.

ChippedHammer
November 13th, 2007, 02:45 AM
Ive heard of this before, don't know where but someone mentioned that on some cheap hammers the NC is poorly applied and flakes off.

Cheap pretty much free source of NC :)

Cobalt.45
November 13th, 2007, 07:51 AM
Hammer faces can and will shatter if struck together with enough force.

Not all hammers, not all the time- just when you least expect it.

I suspect that there's a flaw in the forging that causes it (duh) but it damn sure occurs.

I'm all for the NC theory for the phenomena that Positron describes.

Double-Oh-Zero
November 13th, 2007, 08:38 AM
I tried this at a shop here in SA. It took me a couple of tries but I also got some smoke and a burnt spot on the hammers. Hmm, it does look like NC.

Hammers have been known to shatter. My dad, (who is a carpenter by trade) and I were putting a desk together about a week ago and as he hit the nail with a hammer, It split into six pieces.

hatal
November 13th, 2007, 12:36 PM
Most likely anything made from martensite (rather the austenite) would shatter if driven with enough force. I would certainly believe that the chinese produced shitty steel for hammers by annealing it too quickly or putting too much carbon in it. But explosion... wow

Jacks Complete
November 19th, 2007, 07:35 PM
That's a cheap-ass hammer! The face should be hard, and the rest tough and softer.

The varnish is what is exploding. It's (probably) a cheap NC lacquer, and the entire cheap hammer was probably dipped or sprayed in it prior to shipping to coat the wood for life and the steel of shipping. Or it could be the oil, as someone else said, which is simply exploding under the pressure. 'm sure the OP can tell the difference if he looks closely.

This only works with a cheap hammer, and you will get faster results with a ball-pein against a flat face. Not good for the hammers, though.