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View Full Version : Jointer knife sharpening


Larry Fox
09-20-2007, 9:52 AM
I spent last night doing my absolute least favorite thing to do in the shop - changing the knives on my jointer. I was able to get the alligned fairly easily but test cuts were coming out a bit convex side to side. After some investigation, I discovered that the shop that sharpened them ground them a little concaved. That is, if you stand the knife up vertically and lay a straight edge across the width the straightedge touches the knife at the outermost edge only. You can see light in the middle and I measured it at about 5-7 thousandths. All threee of them are this way so offsetting them slightly won't solve it.

Anyone ever run into this before? Will use eventually knock the edges down or do thye just need to be reground?
Ken Glass
09-20-2007, 10:48 AM
Larry,
Only once did this happen to me. After I showed the shop what I had found, they just said , 'Hey, they are sharp aren't they." You can only imagine my response. All my blades go to Forrest, without exception. They are set up to do all sharpening jobs, and they do amazing work. They are not the cheapest, thank God. If a shop can't do a job as simple as jointer blades, they should not be in the business. Also, if my jointer blades are not excessively dull, I will run a diamond stone across the back side to extend the time between sharpening, but I never take a stone to the bevel.
Scott Whiting
09-21-2007, 9:25 AM
Larry - They will need to be reground. At least for face jointing, for edge jointing a 3/4" board they may be close enough. They will never wear in.

Ken - What you are doing is fine. Just as a caution make sure the bottom of the knife stays flat, just like the flat on a plane blade. You actually can touch up the bevel lightly with a little practice.
Ken Glass
09-21-2007, 1:53 PM
Scott,
I have been honing the blades of jointers for years, and have a guide made for just this purpose to keep the blade flat. This is only a process to lengthen the time between sharpenings. Thanks.
CPeter James
09-21-2007, 2:02 PM
This is my way of combating the problem. I try to sharpen them early and it only takes a few minutes to do it once you get the system down. I use this on both my jointer and planer. Get the green wheel and the Instructions from them. Well worth the money.


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