By Stan Watson, technical director for Diamond Machining Technology
As the 2010 gardening season comes to a close, the employees at Diamond Machining Technology (DMT) have some information to share. Before you put away your pruners and loppers until next spring, it’s best to give them some end-of-the-season care and attention. That means cleaning and sharpening.
Sharp garden pruners and loppers have several advantages over dull ones. The biggest advantage is to the health of your garden plants. Sharp tools cut cleanly, minimizing the plants healing time. Healthy plants will generally bear more and larger fruit, flowers or vegetables. Keeping your tools sharp also makes gardening easier for you since less effort is required when pruning and lopping with sharp blades. Sharpening also protects your investment as quality pruners and loppers are expensive and it only takes a few minutes of your time.
There are a few basic things you need to know:
• when to use a bypass pruner or lopper versus an anvil pruner or lopper
• how to correctly sharpen each type
• which DMT Diamond sharpeners to use
Bypass Pruners and Loppers
Bypass pruners and loppers function exactly in the same fashion as ordinary scissors do with one small exception: there is only one bevel edge on bypass pruners and loppers where scissors have a bevel on each blade. The cutting edge and flat back “pass by” the anvil edge, which is generally at a 90-degree angle to the cutting edge passing by. Bypass pruners and loppers are used only for cutting live plant growth and for those plants that don’t have an exceptionally woody stem.
Anvil Pruners and Loppers
Contrastingly, anvil pruners and loppers have a two-sided bevel blade which closes down on a flat metal anvil during use. Anvil pruners and loppers have greater cutting power than bypass pruners and loppers and are designed to cut dead growth and woody plant stems. Should you attempt cutting through dead or woody stems with a bypass pruner or lopper, you run the risk of “springing” the blade and damaging or ruining the tool completely.
Sharpening Bypass Pruners and Loppers
The first step in sharpening any pruner or lopper is to remove any dried-on sap, grime and dirt from the blade using any one of a number of appropriate cleaners available. You can use an old tooth brush, rag or steel wool to apply the cleaner and work off the dirt.
Using either a DMT Diamond Diafold Flat File (the Coarse grit is best) or a set of DMT Diamond Dia-Sharp Mini-Hones (starting with the Coarse grit first) will work perfectly. Which product you choose is largely a matter of personal preference. The Flat File is best for small, tight clearance applications and accommodates a longer stroke. The Mini-Hone is available in Extra Fine grit, which the Flat File is not.
Holding the pruner or lopper handle that the blade is attached to in one hand, and standing under a fairly bright light, rotate the blade up slowly, starting with the flat backside of the pruner blade parallel to the floor. As you rotate the blade up slowly, look for a reflection of light back up to your eye from the cutting bevel and stop where the reflection is the brightest. You now will have the cutting bevel level. Now hold the Flat File or Mini-Hone level and stroke into the cutting edge from the heel of the blade to the tip in one smooth stroke.
This method ensures you will both accurately match the original bevel angle and since you are stroking into the cutting edge, you will not roll up a burr on the backside of the blade. When using the Diamond Diafold Flat File, make eight to ten strokes across the bevel and finish up with lighter pressure for a smoother finish. When using the set of Diamond Dia-Sharp Mini-Hones, first make six to eight strokes across the bevel with the Coarse Mini-Hone followed by the same number of strokes with the Fine Mini-Hone and, lastly, with the Extra Fine Mini-Hone.
Sharpening Anvil Pruners and Loppers
As mentioned earlier, the first step is cleaning away the grime. There is a simple technique for sharpening both sides of the blade and not leaving a burr on one side. Use the same DMT Diamond Diafold Flat File or the same set of DMT Diamond Dia-Sharp Mini-Hones (progressing from Coarse to Fine to Extra Fine). Hold the pruner or lopper with one hand with the cutting edge of the blade facing away from you. Use the same method described above to “level the bevel” and hold the Flat File or Mini-Hone parallel to the floor also. (Another tip to find the correct bevel is to color the bevel edge with a marker so that you will be able to see after a stroke whether you’re too high, too low, or right on.) Stroke away from the cutting edge from heel to tip ensuring that you remove an even amount of material from the entire bevel edge. Because you are stroking off or away from the bevel, you will likely roll up a burr on the opposite side, but that’s okay.
Now rotate the pruners so that the cutting edge is facing you. Level the bevel again and you will see that now you will be stroking into the cutting edge and will therefore remove any burr you just created. (Remember with the Mini-Hones to repeat the “off edge/into edge” process with the two remaining grits.) One important difference to remember between sharpening anvil and bypass blades is removing an even amount of material from the anvil blade. Since it closes down on an anvil and doesn’t bypass it, any excess material you remove from one section of the blade as compared to another will leave you with a gap between the bevel edge and the anvil, and that will result in incomplete cuts.
After you have completed sharpening with the DMT Diamond Diafold Flat File or DMT Diamond Mini-Hones, apply a small amount of lubricant of your choice to both sides of the blades and/or anvil. This serves two purposes; it keeps the joint lubricated and helps prevent the accumulation of dirt, sap and grime. You can also protect wooden-handled tools with linseed oil or a coat of varnish, and be sure to store your tools in a dry place. By following these steps, your tools will be ready whenever you are, any time of the year.
For a video demonstration of the tools and techniques described in this article, visit www.dmtsharp.com/video/pruner.htm. Check out more information at www.dmtsharp.com.