I have the Makita water sharpening outfit and have used it to put a great edge on the blades for my jointer and planer. However, I recently discovered I had ground the outside edges much more than the center, resulting in a curved cutting edge. Can anyone offer help on what I am doing wrong and how to remedy it. By reading the archives, most seem to like the Makita sharpening system, especially for sharpening long jointer and planer knives, so I must doing something wrong.
I am thinking I will need to send the curved knives out for sharpening to get a straight edge, and only use the Makita sharpener to put on a secondary bevel, and do that very carefully once I figure out what I have been doing wrong. Any thoughts??
Replies
Larry, Having made this discovery means that you are half way there. In the future just pay a little more attention where you apply the pressure, and check how things are going more often.
You might consider a one-time trip to a pro sharpening shop in order to get the knives ground straight again. Their grinding machines will do this far better than you can by hand. I pay 75 cents per inch for sharpening, so a set of 4 12" knives costs $36 to sharpen (much cheaper than buying new ones). I also find I need to sharpen only 3-4 times a year at most, so it's also cheaper than buying a knive grinder!
Larry,
There was a discussion a week or two ago about the Lee Valley girding machine (while not a wet grinder it is also a flat disc type of grinder). Someone pointed out that while the RPM is the same at the center of the disc as it is at the outside edge of the disc, per revolution the edge of a long blade on the outside edge is subject to more disc area than the portion of the blade in the center. This may translate to a very wide blade being ground/honed faster at the end of the wheel than in the middle. For a plan blade or even wide chisel this is insignificant, but for a jointer or planer knife it may not be. Not sure if this is your problem, but it's a theory.
Cheers,
--M
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