Hand-Honing Tips for Cutter Knives
Remarks on honing and deburring cutterhead edges, and some thoughts on knife materials and performance. April 30, 2006
Question
Is anyone using honing stones to polish up knives after they are ground? If not, what's a better way?
Forum Responses
(Solid Wood Machining Forum)
From contributor C:
Most people use some kind of stone for deburring their knives after grinding. Different operators prefer different types of hones. The list includes slip stones (in both aluminum oxide and faster cutting silicon carbide), Arkansas stones, ceramic, rubberized abrasives (like Cratex), diamond hones and other types of dressing sticks.
From contributor R:
Get a couple of different ones - it's all personal preference. I like the fine India stones (Teardrop type) for deburring and the ceramic stones for getting out small scuffs while running the product. Need any more info, give me a call.
From contributor A:
One thing that should be mentioned is that honing is a skill that takes time to learn properly. When training new operators at the mill, it would generally take 6 months to a year before new guys could hone reliably. Any time you do something to an edge, you stand as good a chance of making it worse as making it better. I think honing is a crucial part of making a new set of blades as well as keeping nicks out of a run. Try to practice on the ends of runs when knives are dull to see if you can refresh them so you don't have to learn with a 900 lb gorilla deadline breathing down your neck. Be patient with yourself while you learn. It's worth it.
From Dave Rankin, forum technical advisor:
When I deburr a knife that has just been ground, I use a tapered hone stone and a rubberized block to do the job. The hone costs around $5 and the rubberized block is under $4. I do not hone a knife during a run. The reason is what contributor A stated - it is a skill that takes time to develop. For those skilled folks, there are a couple of things that they have learned. Get a good stone and use a good lubricant when honing.
From the original questioner:
How do you keeps nicks out of your knives if you are not honing? Last night I ran an m2 knife at 12 degrees on some soft maple. I needed to run about 750 linear feet and I made it through about 200 feet before the knives were so dull the finish was unacceptable and I had to pull the heads to regrind. Am I doing something wrong or is that a common life of one grind?
From contributor R:
Try using a better quality of steel. Although M-2 is widely used, it is one of the lowest quality available. Try a M-3 or a V3N, or a WKW opti. I believe Dave carries a brand that he developed as well. Also try using a 20 hook angle head. If it's not tearing out say with the 20 degree it will last longer because less surface area is touching the lumber. If it is tearing out, then you will have to stay with the 12 degree heads.
From contributor C:
The kicks may be a result of the finish grind on the face edge of your knife. What type of M2 are you using? Steels that are lineally ground (WKW for instance) rather than Blanchard surface ground (many import grade steels) have the finish grind lines running along the length of the knife. Surface grinding is a cheaper process; however, the resulting radial grind lines reflect into small kicks in the knife you can never grind out because they run the entire width of the knife.
Soft maple should machine well with a good, high quality M2. Using 12 degree heads helps reduce tear out as well on this wood species. Milton-Bradley successfully used this combination for many years in making Scrabble board components and Jenga blocks out of soft maple. The lineal footage lengths you're experiencing are abnormal for soft maple. Hard maple is a different animal and usually is machined better with carbide. Deburring will help extend knife life as well.
From Dave Rankin, forum technical advisor:
Maple has mineral streaks in it and this is one of the main causes of nicks in the knives. A lower hook angle may help, as has been stated. The use of lineal ground knife steel is best (note: this is also called surface grinding). Blanchard or radially ground steel has shown to nick more often due to the small grind lines that cross the cutting edge.
MSI developed and patented a knife material called DGK that has worked very well in maple applications. It is a M2 base steel with a heat reflective hardened coating. The coating does not change the way that you grind the knife except you do not hone the face at all. This will damage the coating. In maple we have customers running over 25,000 lineal feet on single knife work before regrinding. The biggest benefit is the cost. It only adds about $2 or so an inch over high quality M2 steel. This is much less than carbide, which also works very well. If your runs are under 25,000 lineal feet, then the DGK is normally a better choice.
From contributor J:
You mentioned using a twelve degree hook angle. The pocket the knife sits in. But what angle on your grinder are you using to sharpen with? Your back clearance, and if you use a finish grind, what angle is that? This is important and I am quite surprised it hasn't been mentioned yet. Also, I agree that M3+ is much better for hardwood. You're not making money with your heads on the grinder instead of the moulder.
From the original questioner:
The back angle that we are grinding is real close to 30 degrees I would say... 32 degrees and the tip we are grinding to about 45 degrees.
From contributor J:
This will probably open up a bunch of responses, but I believe your finish grind is way too steep. If you choose to finish grind the tip, try a 20 for starters. Just my experience. I grind only one angle at 23 degrees with no finish grind and can go hours/lf with M3 (deburr, of course) with hard maple, oak, etc. assuming everything on the machine is set right. Experiment with your grinding angles. You will find you can get a lot more L/F run in between grinding than you are. The honing? I would like to learn more about that.
From contributor F:
Just want to let folks know about an inexpensive and great lubricant for honing. It's called "kerosene" or "white gas" sometimes. A can of Coleman Lantern Fuel will keep you in lube for the rest of your life.
From contributor C:
Kerosene and Coleman "white gas" are not same thing! White gas has a very high octane rating and is extremely volatile and highly flammable. Kerosene is used as a lubricant, and there are also specialized honing oils (such as Bear Oil from Norton) that are also widely used for soaking "oil filled" aluminum oxide slip stones. A good homemade honing oil mix is 35 parts kerosene to 1 part of a good lightweight fatty oil (hydraulic oil 46 weight). The lightweight oil in the mix helps to equalize the over-aggressiveness of the kerosene. Kerosene does a great job of keeping the stones' pores open and free cutting. Bear in mind that the rate of evaporation is 10:1 of the kerosene over the hydraulic oil in long term storage!
From contributor F:
I used to mix 'em with oil - now I just use them straight.
