In a reply to a post last week by RaiderDad, I mentioned a story about a
Ball Peen Hammer.Yes, that curious hammer that occupies space in everyone's toolbox that most owners cannot explain or devise the purpose for the odd shaped round end. Oh, once in a great while a person will find it useful to spread a rivet before hammering it flat with the flat side ... but most times that round end never gets used for whatever it was designed for. A curiosity.
The fact is that hammer was in practical use in West Texas in those early days before the 1940s when most farms had a blacksmith shop of some sort to forge tools and metal works needed to keep the farm operating, and to repair metal parts that became worn or dull.
With a small forge, a young kid to operate the handle that ran the fan blower to increase the temperature of the burning coke, an anvil, an assortment of hammers and tongs, and some tools created in that small shop, a farmer skilled as a smithy could keep equipment running and harnesses in good repair.
Now, where the ball peen hammer came in mostly was in sharpening plow shares and points. In the process of tilling soil plows would get dulled to the point they, as the saying went, "wouldn't cut hot butter." So the plow points were brought into the shop for sharpening. Most of you would suggest that was time to get out the grinder and go to work ... but that was not the way it was done. True the cutting edges became dull but most of the original metal was still there, just compressed back and rounded ... as we called it "dubbed." Grinding would sharpen the points but in the process destroy good material. In early days, farmers would place the points in the forge, heat up to cherry red, place on the anvil and with a flat hammer beat the metal at the cutting edge back into its original taper and straightness to an edge about the thickness of a sheet of paper. After the point was cooled, the ball peen end of the hammer would be employed ... beating the points for a couple of inches from the cutting edge. You could see small "dimples" in the metal where the round end of the hammer had hit. In this manner of sharpening a plow share would last a long time ... whereas grinding would wear the points out in a season.
My granddad said that "peening" restored the strength to the steel that was taken out during the heating process. I accepted that as fact since granddad knew everything.
In the 1950s I was stationed in Missouri. The highway department was building a new highway near my house and had condemned a number of old homes for destruction. I was rummagine through one that was vacated and found an old time mowing scythe ... the kind the Grim Reaper is shown with.
I salvaged the scythe from destruction and showed it to my neighbor, an elderly gent who worked for Missouri Fish and Game. He was familiar with the instrument, having used it some years before, and taught me how to mow the tall grass near my house. The conversation grew to how I could sharpen it.
The manner he described for sharpening the scythe blade (about 36"
was identical to the method my granddad used in sharpening plow points ... including the peening with a ball peen hammer. Mr. Thorburn explained that something to the effect that "peening strengthened the blade." He said he had never heard of a mowing scythe "wearing out" and that in earlier times before horsedrawn mowing sickles were introduced in Missouri that the scythes were the only means of harvesting grain and sorghum crops. That was interesting.
Now lets turn our attention from farming to the automobile industry. (Hang with me on this great leap in subjects ... it gets interesting at this point.
In the early days of building automobiles, engineers were inventing and devising new systems, parts, methods at a fast pace ... but were having difficulty with some parts such as axles, connecting rods, crankshafts, valve springs and the like ... they kept breaking.
They knew a problem existed in their metallurgy but could not solve their problems.
In the early days of fabricating auto parts since all had to be heated and forged into correct shape, all had a layer of scale that had to be removed. The early method of removing the scale was by sandblasting. This was an incredibly messy method and since the sand could not be reused, a wasteful method. Engineers began looking for different ways to remove the scale ... that made use of a reusable agent. By the 1930s they got around to trying steel shot (about the size of #8 birdshot) for the descaling. It worked great and they were able to recycle the shot for additional descaling.
But a marvelous thing happened. Suddenly, they discovered the parts descaled with steel shot was having fewer failures from fatigue. Something about the round steel shot had solved their unsolvable problem of parts failures.
Analysis revealed "dimples" in the parts that had been blasted with shot ... but it would be several more years before they discovered that the secret was "peening" ... something farmers in Texas had been doing for almost 100 years.
And that discovery led them to reopen the mystery of the secret of
Toledo Steel that had been unknown from the start in about 1000AD. Toledo steel swords were known as the lightest weight, strongest, and most flexible of all warfighting blades in Europe through the Middle Ages ... and the process of forging Toledo blades was a closely guarded secret of Spain for almost a thousand years. Auto and metal engineers in 1970 examined old Toledo steel blade in great detail ... and discovered "dimples" along the length ... the mark of "peening." A ball peen hammer was the secret.
We have been brought up on the histories of great discoveries like electricity, incandescent bulbs, radio, etc., about how as soon at the discovery was made that others joined in the chase to develop all sorts of uses and applications in quick succession.
But that was not the case for Shot Peening as the new method of steel balls being fired at metal parts to increase their strength and durability. It was not until 1980 that the first convention of scientists and engineers was convened to share knowledge of the Peening process and to look for more applications of the new science.
Today, shot peening is used in virtually every part of automobile and aircraft engines ... and new uses are being developed in every industry that has metal moving parts in its product. New processes are being devoloped for "shot forming" of aircraft skins. Other materials are being studied, such as ceramic pellets, glass beads and laser beams, as a substitute for round steel shot.
And the thing that started all this commotion was that curiously shaped
Ball Peen Hammer in the bottom of your tool box. (And to think, that West Texas farmers, blacksmiths, and Spanish foundry workers have known the value of that tool for a thousand years!)
Edit: My granddad and Mr. Thorburn, my neighbor in Missouri used the term of "strengthing the material" in regards to Peening. Actually they had no idea what was happening to the metal when they created a "dimple" with a ball-peen hammer ... the just knew it seemed to work in the manner they desired. In recent years after a great amount of study, engineers explain that the good effects from the "dimples" has to do with pre-stressing the metal for compressive loads and solving a problem of growing minute cracks under tension loads. My comment was, "Oh, OK."
[This message has been edited by fossil_ag (edited 10/25/2007 5:32p).]