Wire edge on planer knives
Tips for deburring freshly ground planer knives. January 24, 2001
Question
What is the best method of removing the wire edge from freshly ground planer knives? Is doing this required?
Forum Responses
I'm foreman of a moulding operation. We always remove the wire edge. Some people use a deburring stick that you can purchase from your tooling supplier. We use a 6" or so piece of scrap wood. Try to keep from using the same part of the scrap, so you won't dull the knife with the material that becomes inbedded in the scrap.
Try removing the wire edge before making a final pass in the grinder. This should provide a keener cutting edge for quality work.
Use a fine stone to run across the face of the knife before you make the final grinding pass. This will remove any burr already built up and minimize the wire edge left after the final pass.
Deburring of the knives is very important. At the Grinderman's Association Training Center, we use several things for deburring. They range from a tapered hone or slip stone to a Cratex block. After we break the wire edge, we use a small piece of hardwood to wipe off the wire.
If you do not deburr the tool, that wire edge can cause nicking of the tool. This is not the only cause of nicking, but is a common one.
Dave Rankin, forum technical advisor
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor A:
Back in the dark ages (1960-70) we all kept a piece of copper tubing on the grinder and pushed the wire off with the tubing and intentionally stroked from the heel to the point of the knife to burnish the edge of the high speed steel. We used "hollow grinding" (most still do today) and learned to begin the stroke with the contact and the pressure on the heel of the knife and a lighter but constant pressure on the edge. We thought that doing this broke down the millions of super microscopic jagged edges that the grinding wheel had imparted into the intersection of the face of the knife. The old men told us, and sometimes showed us (I never saw it) the swarf that would be imbedded into the edge of the knife if you did not "stroke the knife". They would run just a few feet in white pine and I always said I saw "it". Now at 62 years of age I am not sure I saw something that was stuck on the face of the knife that would not have been there on a knife that had not been properly stroked.
We never pushed the copper tubing into the front of the knife to produce a shaving of copper. We also had no successful carbide tipped saw blades and the saw blades were all either spring set or swedge set teeth. We "gummed" the rip saw and combo saws on grinders to the "strike" point we had been provided with by the saw operator. We did the same thing with fine cutting cross cut saw blades and filed them with Foley or Belsaw stroke files that were three sided and highest quality. A good filer could hand you back a blade that was filed so lightly that the back or land of the teeth were almost a mirror to peer into. I am sure that very fine grit crystlon and India slip stones are far superior to the pieces of copper tubing we used (and more expensive). I also know that filers need to know and understand how to hold and push these stones to get just the right edge so the knife starts out "licking" the fibers off the board - due to its uninterupted smooth sharp edge. The cratex sticks and rounds are very nice but require a great deal more caution than the fine stones. The abrasive is impregnated into the rubber parent material but it is just a bit inconsistent in grittiness. I would never use the coarse or medium grits.
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KnowledgeBase: Solid Wood Machining
KnowledgeBase: Solid Wood Machining: General
KnowledgeBase: Solid Wood Machining: Tool Grinding
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