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How do I know if I need new planer blade

Dave Worsencroft's picture

I have a Dewalt 733 12 1/2 inch thickness planer and have never changed the blades since I bought it five or six years ago.  I use it about 4 to 6 times a year and I am wondering what symptoms should I be looking for to indicate that it is time to replace the extra set of planer blades.  I typically slice off a 64th to a 16th of an inch of wood per pass.  Recently I have had to push the wood through the planer even when I take off a 64th of an inch.

bldrbill's picture

(post #102908, reply #1 of 12)

One way to tell if the blades are dull is by the noise.  The planer will be much louder if the blades are dull.  Also, you'll start having more grain tearout.


Edit to add--the feed problem might be caused by pitch buildup on the feed rollers.  Clean them and see if that helps.


Edited 7/7/2009 10:25 pm ET by bldrbill

flairwoodworks's picture

(post #102908, reply #2 of 12)

Dave,

The quality of cut also degrades, as one might expect.

Chris @ www.flairwoodworks.com
and www.flairwoodwork.spaces.live.com)


 - Success is not the key to happiness.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

Chris @ www.flairwoodworks.com
and http://flairwoodworks.wordpress.com

 - Success is not the key to happiness.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

ring's picture

(post #102908, reply #3 of 12)

Dave, I seriously doubt that you would need to change blades after such occasional use. There are a few materials that will quickly dull blades - teak, for instance. And of course running plywood or other composite materials through. But with common hardwoods I find that our planers normally start to show wear after about 50 hours of use.

Look at the blades and check carefully with a finger, comparing with a sharp blade. When they're dull you can easily tell by feel. And look for other causes for the difficulty in feeding. Are the feed rollers and bed clean? Maybe their height needs adjusting?

oldusty's picture

(post #102908, reply #4 of 12)

   Hi Dave ,


            Sounds like the only symptom you have is  " had to push the wood through the planer "


         My first thought is to clean and wax the bed and check the feed rollers for build up . Depending on what the rollers are made of steel or Urethane , you may be able to remove any pitch or such.


      Try spraying some WD or  lube on the roller ends and other moving things , and check and see if there is a feed roller adjustment that needs attention


     The waxed bed or glazed rollers effect the feed more so then the knives .


      Sounds like the planer does a good job other then the feed so this makes me think the knives may need sharpening but prolly are not causing the feed problem.


     Some planers have a chain , problems with sprockets stretched chains broken teeth can all cause feed problems also .


            regards           dusty

forestgirl's picture

(post #102908, reply #5 of 12)

Niine times out of ten, maybe even 99 out of 100, problems reported here about feed problems on a lunchbox planer are solved with cleaning the rollers.  Waxing the tables never hurts (if you use the right wax, LOL). 


Planer blades can last a long time, or a short time, depending not only on what type of wood you're planing but also on how clean it is when you feed it through.  I've learned the hard way to make sure I'm not feeding any kind of grit through the planer on the surface of the lumber.


Seems like it could be possible for blunt knives to cause feed problems, but seems likely you'd notice other problems before things got that bad -- tearout, choppiness and the like.


forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

oldusty's picture

(post #102908, reply #6 of 12)

  Hi FG ,


           The  Knives don't do the feeding .

forestgirl's picture

(post #102908, reply #7 of 12)

Yeah, I know, but dull ones do seem to have an effect.  Or is it just because when the knives are dull, the rollers are usually dirty?  ROFL!

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

JohnWW's picture

(post #102908, reply #8 of 12)

No, the knives don't do the feeding, but a dull set of knives require quite a bit more feed pressure which is one cause of slipping.

John White
Shop Manager for FWW magazine 1998-2007

John White Shop Manager for FWW Magazine, 1998 to 2007

forestgirl's picture

(post #102908, reply #12 of 12)

Thank you, John, glad there is a reason!

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

JohnWW's picture

(post #102908, reply #9 of 12)

Dave,

Unless you have been very disciplined about using the full width of the blades, by not always feeding wood only in the center of the machine, you will find that the outer edges of the blades are probably still as sharp as new. If you compare the ends of the blades to the central area, I just drag a finger across the edge, you will be able to get a sense of how dull the blades have become.

John White
Shop Manager for FWW Magazine, 1998-2007

John White Shop Manager for FWW Magazine, 1998 to 2007

Dave Worsencroft's picture

(post #102908, reply #10 of 12)

Am going to clean the rollers today and then check the blades.  Thanks to all.


Dave

Shoemaker1's picture

(post #102908, reply #11 of 12)

Hi Dave
I have the same machine and have but over 4000 bd feet through it and maybe on blade 4. My roller started to slip after planing pine. Clean the rollers and blow all the dust out from the adjuster chains.

I have run a 600 grit diamond hone down the blade and it seemed to help get a few more feet through. It you give a few swipes and try a board and there is a big differance, time for new blades. IIRC are they not double edged?