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More on sharpening pruning tools

This month’s blog is a continuation (and expansion) on a couple of issues which were briefly covered in last month’s blog on maintaining pruning tools. This has come about because of questions we’ve had from customers regarding the wearing down of cutting blades when using sharpening stones. We’ve had this query from customers sharpening a variety of tools including secateurs, loppers and electric pruning shears.

Some tools are sold with sharpening stones which can be quite coarse. Stones are a very effective tool for sharpening however, with overuse coarse stones can ‘eat through’ your blades very quickly. Users can often also be guilty of overusing stone (over sharpening) their tools and if they’re using a coarser type stone this will increase the amount of wear on the blade.

Our recommendation for sharpening:

  • Keep the blade in good condition with regular, light sharpening.
  • Use diamond sharpeners – a coarser one to remove burs and finish with a finer one to polish the edge. Note: when we use the term ‘coarse’ to describe a diamond sharpener, these are not as coarse or abrasive as coarse stone.
Diagram of sharpening a pruning tool blade

Sharpening your cutting blade (refer to diagram above)

  1. Note the small bevel on both sides of the cutting edge
  2. Trials show maintaining these angles will give its best performance.
  3. Use the coarse diamond sharpener first.
    Hold the handle of your diamond sharpener in your right hand, lay the sharpener on a 12deg angle, lift your hand so the diamond sharpener is about 5mm up off the 12deg angle at the back side of the blade.
    The diamond part is now fitting the small 20deg angle on the cutting edge, sharpen in a rotary movement.
  4. Note there is a cutting bevel on the mating face of the cutting blade, sharpen this as well. If you don’t you will find over time it gets rounded and can cause the blades to spread apart and not give a good clean cut.
  5. Repeat the process using the fine diamond sharpener.
  6.  As the diamond sharpeners work quickly, there is no need to spend a lot of time sharpening. Only about 10 rotations of the sharpener on each side is enough. Check your blade from time to time and repeat the process as necessary.  Good quality steel blades may only need sharpening once a day, even with continual use however, harder wood will wear the blades more so there in no hard and fast rule on this.
  7. We recommend using a 75/25 mixture of salad cooking oil and Methylated spirits as a lubricant for the Pro-Pruner. This mixture keeps the Pro-Pruner and your sharpeners lubricated and clean.

Sharpening Forestry Loppers