What is Peening?
Peening is the art of cold hammering the edge of the blade to draw it out and restore the ideal cutting profile. It is also used to tailor the blade edge to the task in hand (eg ultra-fine for lawns, more robust for mowing weeds) and to repair damage to the blade edge.
Why do I need to peen my blade?
In the field a sharpening stone is used to sharpen the blade edge, often as frequently as every 5 minutes, to keep the blade sharp and cutting well.
After repeated sharpening with a stone the blade edge gradually becomes worn back into the thicker metal of the body of the blade, the profile of the edge is altered and it becomes less efficient at cutting. The mower finds he is having to sharpen more frequently, the blade is not holding it’s edge so well and mowing is becoming harder work. It’s time to peen the blade!
How often do I have to peen my blade?
The frequency in which a blade needs to be peened depends on the blade and the work it is being asked to do. Mowing lawns and meadows require a fine, ultra- sharp edge and so more frequent peening of the blade is necessary (something like after every 4 hours of mowing.) Less frequent peening is required when mowing rougher grass and weeds. A very fine edge is not required to mow efficiently in these circumstances and would be more vulnerable to damage.
What is a Peening Jig?
The Peening Jig
has been devised to make the art of peening more accessible to the beginner. The blade is placed between the first cap and the base of the jig. The cap is struck repeatedly with a hammer as the blade is drawn through the jig producing a line of blows near the blade edge that draws out and thins the metal. The process is repeated with the second cap, which is shaped so as to create a line of peening closer to the blade edge then the first.
The jig is relatively easy to use and requires less accuracy then freehand peening. It produces good results for most circumstances, and can produce excellent results with practice. Full instructions are provided in the book supplied in the scythe kits. Phil started peening with a jig and we recommend most people to do the same.
What is free hand peening?
With the method of free hand peening seen most frequently in the UK, the blade is placed on top of a bar peen anvil. A flat hammer is used to hammer a line a few millimetres back from the blade edge, drawing the metal forward and thinning it. The process is the repeated a number of times, the exact number depending on the thinness and sharpness of the edge required. Each time the hammered line is placed closer to the blade edge, with the final line being on the blade edge.
It takes some practice to master the accuracy of the placement of the hammer blows, but once this has been achieved, free hand peening can produce even better results then the jig.
What kind of hammer do I need?
With a peening jig, a standard hammer about 1lb / 500g in weight can be used. The condition of the face is unimportant as it does not come into contact with the blade edge.
Peening with an anvil requires a more specialised hammer. We now supply peening hammers from Vaughnes. These are supplied polished and ready to use and are probably the best peening hammers that can be purchased new in the UK. The face of peening hammers must be kept smooth and shiny as any dint or defect in the face of the hammer will be imprinted in the blade being peened. A peening hammer should be reserved for peening with an anvil only and NEVER used with the jig, or worse yet, to hammer in nails!
Phil’s Masterclass on Peening, West Country Scythe Festival, 2011