Help me diagnose this parting issue

Tell you how I sharpen a parting blade.
  • Put the blade in a parting tool holder and lock it down.
  • Adjust table angle to 7 degrees.
  • Take belt off belt sander and use a square to align the tool holder 90 deg to the platen. Replace belt.
  • Touch the blade to the belt for a second or less, just enough to grind a fresh surface.
  • Take blade out of tool holder and hone the top flat on an extra-fine diamond stone.
All of this takes me less than a minute and the blade is ground straight and cuts clean. I may do this once every 6 months to a year. In between sharpening I just hone the top and the blade stays sharp.

Not a lot to it. And I use the thinnest blade I can get away with.
 
mikey said:
Tell you how I sharpen a parting blade.
  • Put the blade in a parting tool holder and lock it down.
  • Adjust table angle to 7 degrees.
  • Take belt off belt sander and use a square to align the tool holder 90 deg to the platen. Replace belt.
  • Touch the blade to the belt for a second or less, just enough to grind a fresh surface.
  • Take blade out of tool holder and hone the top flat on an extra-fine diamond stone.
All of this takes me less than a minute and the blade is ground straight and cuts clean. I may do this once every 6 months to a year. In between sharpening I just hone the top and the blade stays sharp.

Not a lot to it. And I use the thinnest blade I can get away with.
Click to expand...
What do you hone the top with? The parting blades I have are slightly concave on the top. Ceramic rod?
 
I use an extra-fine diamond stone. My blades are all flat on top. AR Warner makes good ones.
 
Have had the same problem when parting plastic with the thin blade ( 1/16 inch ) sticking out by about 3/4 inch. Problem solved by ensuring the perpendicularity of the blade with the aid of DTI.
 
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I have found that the squareness of the tool across the tip is the most important geometry on a parting tool. While I agree that getting the blade perpendicular to the work is important, if the tip is not ground accurately then it will steer and bend a perfectly perpendicular blade. So, take special care when sharpening your blade. Honing is simple, just get the top flat.

As to blades with concaves ground into the top, this is a common feature on many import blades. Some higher end blades had them, too, but they were not as common from those makers. The idea is that the concave helps to curl the chip, which it does, but it also causes a lot of wear at the corners of the tool. I tried one once and it went in the trash shortly after I tested it. Just for myself, I prefer a P-type blade with a flat top. A P-type blade has a 5 deg bevel on either side of the blade that reduces cutting forces. Chips curl cleanly and the entire blade cuts evenly. Empire, Eclipse, Morse, Cleveland all made good blades but are hard to find. Nowadays, the best blade that is easy to get is made by AR Warner. LMS sells them.
 
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