Scythe peening = cold working

[Jan]

The prevailing way the scythe leading edge was formed (in continental Europe) for many generations is peening. Peening is cold hammering the cutting edge of the blade. Peening results in drawing out and thinning the steel at the edge. After peening the edge is finished and maintained with wheatstone.

From the metallurgical point of view peening is a mixture between work-hardening (cold working) and steel over-working. Peening is primarily a cold working process but I have observed some self-heating also*. Peening hardens the metal at the edge. Peening may induce desirable surface compressive stress, because cracks will not grow in a compressive environment. 

One study has shown that the surface hardness of a blade increased form HRC 46 for the core of the blade to HRC 53 in the hand hammered region. The test did not include the last 1mm zone which actually does the cutting and determines retention of keenness. So it is possible that the very edge is considerably harder.

I have never mastered the peening technique though I have inherited the equipment for it – a special stool with wide convex anvil and scythe hammer very similar to the one shown on the picture below.
   
From my childhood I remember well the characteristic ringing sound of the peening anvil and hammer which was an essential part of rural atmosphere. Reapers were peening their scythes each evening.
 
More info http://scythecymru.co.uk/scythes-for-sale/peening/
 
Jan

P.S.: * I have noticed that under hard hammer blow a blue oxide spot formed on the edge which means that the temperature locally increased by some 300°C (540°F).

[Ken S]

Interesting, Jan.  Thanks for sharing.

Ken

[Jan]

Yes, Ken, the old mowers understood what we are now studying with metallurgical methods.

Scythes are beginning a comeback in US also because they don't make noise.
It is perhaps the best technique to mow mountain meadows.  

           

[Bubby]

Very interesting for sure Jan. I live in the same agricultural area that Mike B. is from. Scythes are common here but mainly relegated to hanging on shop walls as decorations now. I own several and have noticed the peculiar marks left on the edges of some of the older pieces. I always assumed that the marks were simply left over from the blacksmithing process but now I believe they may have been created out of the sharpening process.

The scythes used here were the earliest means of harvesting wheat, particularly wheat that was to be saved as seed for the next crop though mechanization quickly made them obsolete even for that purpose. The wheat was laid down and then bundled. Early on the bundles were rolled over with horse drawn threshing stones to separate the head from the stock and then extract the wheat from the head. All these were soon replaced by threshing machines. "Pitching bundles" (into a threshing machine) is a term familiar to anyone over the age of sixty here.

Here's a little trivia for you. Mike and I both got our undergrads at a small college here. The school nickname is the "Threshers". Here's a picture of the threshing stone that sits on the school campus today and when we attended.
   

[Jan]

Mr. Bubby, thanks for your recollection, appreciated. The nice threshing stone was already an important mechanization. Smaller farmers here used only grain flail for threshing.

       

[Mike Brubacher]

This is an interesting thread Jan so thank you for beginning it. I've read about grain flails but never seen one. I see the downside now of inviting people onto the thread who you have known for 45 years. Bubby knows where all my skeletons are buried so I hope they stay buried. So here is a little trivia on Bubby. His name is Bob and his wife's name is Debbie. To their close friends they are known as Bubby and Dubby so I insisted when he signed up for the Exchange that he use his Kansas nickname. 

Like Bubby I have a few of these harvesting instruments in storage as well. Here's a picture I lifted from the internet of the two most common styles found in Kansas. I can still remember seeing my Great Uncle Jake using one of these around his out buildings on the farm. He had a push-type reel mower for the grass around the farmhouse and the scythe for the weeds.
   

Now here's something I put a few hours in on as a kid. Great for cleaning sunflowers out of fence rows. I didn't think it was great, Dad did. A good, healthy Kansas sunflower has a stalk on it as tough as a pine tree. Dad referred to this tool as a "sickle" though. 
   

Every cutting tool we owned, including mom's butcher knives, were sharpened on a bench grinder. I don't remember much burr removal going on unless it occurred as mom was slicing the pot roast.

Finally, here is what we use today for weed removal. Clearly a waypoint on our descent into physical lassitude.
   

[Mike Brubacher]

I did forget to comment on your excellent photos in my original post here Jan. I enjoyed the two pictures of hay cutting very much. Beautiful hay meadows and surrounding scenery. The third picture was the most scenic of all though. Apparently she stumbled and fell down in the process of cutting hay. Excellent background research into the dangers associated with cutting hay.

[Jan]

Thank you for your input, Mike, highly appreciated!  

I have grown up in a town and so I know all the ancient tools only from summer vacations spent at the farm of my grandfather. Some of them I have inherited and preserved for future generations.

       

Just imagine how much sharpening and peening the sickles must have behind.

[Mark Reich]

Very interesting, Gentlemen!

By the time I was using these tools, I sharpened them with files. I have no recollection of peening the edges of anything, but that sounds like a very very serious skill!

The little sickle could cut jillions of weeds per day, depending on "motivation". I was happy to discover I was big enough to use a grain scythe one year, but then more weeds- bigger ones- became something to deal with. Bull thistles can get bigger than a man's wrist!

I'm pretty sure that's why I take such great delight in spraying weeds now. Using those tools can make one Hate weeds.