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Resharpening Planer Blades

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  • Resharpening Planer Blades

    I use my Boxford Union tool & cutter grinder to resharpen the blades from my 10" wood planer - the t&c grinder has *just* enough table travel.

    I've made a jig that bolts to the table to hold the blade at the correct angle for sharpening. I can arrange the setup to grind onto the edge, using a cup wheel, or along the edge using the periphery of a wheel.

    Onto the edge, or along it - pros & cons, does it make any difference?

    Thanks,

    Ian
    All of the gear, no idea...

  • #2
    Well Ive used my grinder along the edge .got rid of the burrs ..touched them up with an oil stone...i could slice phone books with them and shave myself ..plonked them in the planer ..10 mins later there are little cresents missing from the edge...no nails in the wood.

    so i say do the opposite and and grind at 90 degrees to the edge ..and see what happens.

    cause my way isn't working

    all the best.markj

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    • #3
      my experience FWIW

      always grind "towards" the blade/knife

      this applies to my little tormek wet grinder or the beast I used at a mate's business which used to do printers' guillotine knives and metal shears up to 12' long (12', no typo)

      in the case of the tormek, I'm manually traversing the tool across the wet stone, giving a hollow grind, but always "der scratches goes in line with der cutting" whether for timber or metal

      the abovementioned monster grinder traversed a bloody great 3PH induction motor grinder head along the ways, shaving whatever was held in the bed, adjusted to the correct angle, of course

      the main thing is, the grinder head held segment stones and could be tilt adjusted to provide a very slight hollow grind on the edge of paper guillotines or a nearly square edge if you wanna crop 2" steel plate

      I think what I'm trying to say here is, use the cup stone and cut towards the "body" of the blade with a very slight hollow if your TCG will accomodate that

      hope I have understood your question

      slainte, Lin
      Just got my head together
      now my body's falling apart

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      • #4
        There are companies locally that do this professionally and often the cost to sharpen a set of planer blades is so cheap its not worth risking messing them up.

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        • #5
          I have several sets of wood planer knives. When a few get dull I take them oul to Kukenbaker Sharpening service on Half Mile Road. Cost me about $30 to get two sets ground and in that time get to BS with a few local woodbutchers, look at his kid's rabbits, pet the cats, and eat a cookie. Hell of a deal.

          The knives come out straight and sharp equal weight and while I'm there order a new set (he can still get the good M2 knives) to replace a set I notice are getting narrow. Nice way to spend a couple of hours..

          I'd do about anything to avoid sharpening planer and jointer knives especially if it's pleasant at the place of avoidance.

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          • #6
            Make sure you balance the blades in pairs to within half a gram or better. My wife does that in her shop for all the blades she sells and it makes a big difference to the finish and life of the blades.
            Free software for calculating bolt circles and similar: Click Here

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            • #7
              I have a 12" planer with a two-blade head. I made a "jig" from a length of 2x4 and use a 6"x80" belt sander. Obviously, the blades are ground parallel to the length. I finish on a hard Arkansas to remove any wire edge. In my (limited,)experience, I find that I have to grind each blade about the same amount to remove any oops left by stray staples or fine nails, so they maintain (reasonably) equal weight.
              I also learned that the "off-shore" blades are laminated, with a very thin HSS insert on the edge. They work as well as solid HSS blades, so I guess it is an "oriental economy" thing, rather than a safety issue. (Think how exciting it would be when one of those blades shattered!)
              If the blades are not giving decent service, it MIGHT be too-shallow a bevel angle.
              Duffy, Gatineau, Quebec

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              • #8
                yea if they are chiping, id suspect bevel angle is too shallow.

                I made a machette and after my friend sharpened it, it was getting huge nicks in the blade. I sharpened it again with a really steep bevel angle, just about 1~2mm deep on the tip of the blade, And now it seems just as sharp, but hardly gets a scratch from hiting rocks.

                (Got the idea from the "Micro bevel" stuff they talk about in my lee vally catalog. Put a 2nd bevel on the blade, a few degrees steeper, and its MUCH easyer to sharpen/hone and much stronger if the new bevel is a few degrees blunter, Without losing much chip clearance on the blade or having to greatly alter its profile to try it out.
                Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                • #9
                  I made a planer blade grinding fixture some years ago for our small planer at work. You use the fixture to sharpen the blades on a surface grinder. I'll bring the camera in tomorrow and take a few picts of it and post them tomorrow night.

                  EDIT: JoeLee beat me to it. *LOL* Beautiful job Joe. Mine sharpens all three at the same time but is not nearly as elegant as yours. I was going to post mine but I can't find the dang thing though. We do so little wood work that the blades get sharpened about once every ten years. *LOL*
                  Last edited by DATo; 06-30-2011, 06:23 AM.

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                  • #10
                    I had our planer apart a couple months ago. Didn't even think twice about sharpening them myself- just wrapped them up and sent them out. Putting the blades back in properly was challenge enough.

                    Today I had our dovetail machine apart for some TLC and alignment of the guides. The machine has an issue with one of the air cylinders sticking. At one point it kind of got out of cycle and let the cutter drag past a metal tang. I don't even want to know how much it will cost to replace the diamond-faced cutter-
                    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                    • #11
                      Here is a fixture I made about 10 or more years ago to use on a surface grinder. I do the edges the long way.

                      http://home.earthlink.net/~lhartswick/planer-jig.jpg

                      ...lew...

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                      • #12
                        I don't think it really makes any difference. All of the knives I've seen sharpened by a specialty sharpening shop have been flat ground using a cup wheel. And all of the straight knife sharpeners that I'm aware of use cup wheels. But most industrial size planers that are equipped with knife grinders to sharpen the blades in situ grind on the periphery of the wheel (hollow grind.)

                        Originally posted by aboard_epsilon
                        Well Ive used my grinder along the edge .got rid of the burrs ..touched them up with an oil stone...i could slice phone books with them and shave myself ..plonked them in the planer ..10 mins later there are little cresents missing from the edge...no nails in the wood.
                        You're getting the knives TOO sharp...you don't want them to be like razor blades. You want as much steel backing up the edge as possible without the knife healing or burning as dirt and pitch accumulate behind the edge . Grind them so that when they are in the cutterhead and contacting the wood you only have about 15 to 20 degrees of clearance.

                        Remember that power woodworking knives scrape more so than cut.

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                        • #13
                          Here are a couple pics of the planer and jointer sharpening fixtures I made. I never tried sharpening into the edge with a cup wheel. I always did them linear. The flash that ends up on the cutting edge is very minimal, I would compare it to gold leaf. A light touch up on the oli stone is all thats needed after grinding.

                          JL................




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                          • #14
                            Thanks for the repies so far. There seem to be 4 camps here:

                            1. Grind onto the edge. This should give the least burrs.
                            2. Grind off the edge - looks like it'll create burrs, but this is how most T&C grinders would work, when sharpening the edges of (say) endmills with the tooth resting on a finger.
                            3. Grind along the blade, as you have to do with long blades being sharpened on a surface grinder.
                            4. Hand the blades to someone else, let them do the sharpening.

                            Leaving the last method aside (this is a hobby to me, and I don't mind sharpening my own blades), back to the original question, which I suppose will apply to producing a sharp edge on anything - is there an optimum direction of grinding?

                            I know about grinding a centrepunch - lengthwise, not around & around, or the point will drop off - or so I'm lead to believe. Does the same not happen when grinding along the length, as with Joe Lee's beautiful jigs?

                            I've been grinding the planer blades at 45 degrees - not sure how much clearance this gives, as I haven't measured the rake. I just followed what the manufacturer had done. Blade life seems ok - nails permitting. I've also been grinding onto the edge, as this is how my jig's set up.

                            Ian
                            All of the gear, no idea...

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                            • #15
                              Hi Ian,
                              I have a small blade grinder for my 3inch electric wood work planers that I bought years ago. It is a type that you clamp the planer in and uses the planer belt to run the wheel which is a small cup wheel that grinds towards the blade.
                              I have also used this to sharpen my 500mm thicknesser blades and it seems to have worked fine from the results I am getting.

                              Dave

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