Planer knives

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Forum topic by Glen posted 02-19-2015 08:18 PM 879 views 1 time favorited 13 replies Add to Favorites Watch
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109 posts in 2500 days

02-19-2015 08:18 PM

Topic tags/keywords: question

Does anyone have an inexpensive way of sharpening planer knives?

-- Glen

13 replies so far

View stefang's profile


15512 posts in 2757 days

#1 posted 02-19-2015 09:32 PM

  1. Get a board at least 1/2” thicker than the width of your planer blades and about 5” wide and 6” longer than your plane blades. MDF works well for this.
  2. Cut two lengthwise parallel grooves in the board from end to end with the same angle as your planer blades and also the same width as the thickness of your planer blades to a depth a little less than the width of you planer blades. the grooves have to be pointed from bottom to top towards the opposite edge of the board and an inch or two apart.
  3. Insert the knives in the grooves and the bevels should be slightly protruding from the top the grooves. The knives should be placed so that there is 3” left on each end of the board to use for clamping it to your bench.
  4. Check to insure that the bevels are the same height or very close to it.
  5. You need a sharpening stone or MDF with different sandpaper grits glued on and nice with a piece of wood glued on the opposite sides of the MDf to use as a handle. I use my DMT 600/1200 grit diamond sharpening plate for this purpose.

Please don’t hesitate to ask if you need clarification on any of the above explanations.

-- Mike, an American living in Norway.

View DrDirt's profile


4143 posts in 3165 days

#2 posted 02-19-2015 09:37 PM

Just send them out.
Planer knives are only a ccouple times a year.

15 inch knives are 8 bucks to sharpen. If you value your own time at all, you are spending more than 8 dollars messing with jigs and such.
aka Connecticut Tool and Saw

-- 'Political correctness is fascism pretending to be manners' ~George Carlin

View MrUnix's profile (online now)


4043 posts in 1622 days

#3 posted 02-19-2015 09:56 PM

I send mine out also.. not worth the hassle for the results I get trying to do it myself. My local shop does a spectacular job and always returns them in perfect shape and better than new. Although around here, they charge $1 an inch!


-- Brad in FL - To be old and wise, you must first be young and stupid

View Kazooman's profile


616 posts in 1375 days

#4 posted 02-19-2015 09:59 PM

I guess it depends on the planer. For most of the bench top models, like the popular Dewalt DW735, new knives are as cheap or cheaper than sharpening. I assume you are talking about a more substantial machine.

View Quanter50's profile


270 posts in 1719 days

#5 posted 02-19-2015 10:10 PM

I’ve noticed more than once that when I send blades out to a “Professional Sharpener” (via. a local hardware store) they came back wavy. When you get them back, put them against a window that looks outside (like you would use a light table). Put them sharpened edge to sharpened edge. Check them against each other you’ll see what I mean. I sharpened them better myself with my Grizzly G2790 Universal Knife Grinder. Anyway, I resolved my planer knife sharpening problems and bought a Spiral Cutterhead for my 15” Planer.

View Roger's profile


19714 posts in 2227 days

#6 posted 02-20-2015 07:42 PM

Lotsa good info above.

-- Roger from KY. Work/Play/Travel Safe. Keep your dust collector fed.

View TheFridge's profile


5682 posts in 909 days

#7 posted 02-20-2015 07:48 PM

I’ve had then sharpened with varying results. If you have to grind out Knicks, send em off. Just touching it up? Make a jig.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Ripthorn's profile


1402 posts in 2408 days

#8 posted 02-20-2015 07:57 PM

I have sharpened my “disposable” knives with 1000 grit sandpaper and a tiny bit of water on my table saw top (cleaned immediately afterwards to prevent rust). With just a couple of strokes on each knife, it was cutting better than new. I just laid it on the bevel, counted 5 or 6 strokes along the length of the knife, a couple strokes on the back, and done. Yes, you get great results sending them out, but my 20 minutes and single sheet of 1000 grit paper served me just fine if you only have one pair of knives or aren’t in the world’s greatest hurry.

-- Brian T. - Exact science is not an exact science

View SASmith               's profile


1850 posts in 2410 days

#9 posted 02-20-2015 09:06 PM

Here is my method.
Click for details

-- Scott Smith, Southern Illinois

View Glen's profile


109 posts in 2500 days

#10 posted 02-24-2015 06:02 PM

Thanks to everyone for the great ideas! I made a jig with 45 degree kerfs cut lengthwise. Then I put sandpaper, grit side up, on my tablesaw top and put the jig, knife side down, on the paper and moved it back and forth about 1000 times, on sandpaper up to 220 grit. Now I can see scratches on the knives. I’m assuming that I need to get finer paper to remove the scratches.

-- Glen

View SASmith               's profile


1850 posts in 2410 days

#11 posted 02-24-2015 11:22 PM

I usually stop at 400 grit.

-- Scott Smith, Southern Illinois

View rwe2156's profile


2126 posts in 904 days

#12 posted 02-25-2015 04:31 PM

I agree with DrDirt.

I just buy new ones.

-- Everything is a prototype thats why its one of a kind!!

View Andre's profile


993 posts in 1229 days

#13 posted 02-25-2015 05:09 PM
This is the jig I use to hone my blades after they are reground.
Guess as long as there are no nicks you could re-sharpen many times ?

-- Lifting one end of the plank.

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