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Discussion Starter · #1 ·
I am working on bringing an older planer into working condition. I sent the 3 knives in to have them sharpened, and when I checked the edge on one it is not straight. There is a pretty significant valley between the ends of the knife. This is on a 15 inch planer. The other two are not as bad.
This is the first time I have messed with a planer. I have to figure out how to set the knives at the right height off the cutter head. I don't see how that can be done if the knife edge is not straight. Any thoughts?
 

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Could it be bowed? They normally clamp it flat in the machine to grind it. It's similar to a grinding attachment often used on a planer and if it's bowed it might just appear not to be straight. Once installed in the planer flat again it might straighten to where the edge is straight again. If the knife is flat then they just screwed up when they ground it and I would send it back to them to be resharpened.
 

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Discussion Starter · #6 ·
Send all three blades back , tell them to do the job properly .
Not having done this before, I was hoping that it wasn't my job/problem that the knives were not straight and that the sharpener either should have caught that or somehow he caused it. I didn't examine them that carefully when I sent them in. I will check with them and see what they will do.

Thanks! :smile:
 

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Not having done this before, I was hoping that it wasn't my job/problem that the knives were not straight and that the sharpener either should have caught that or somehow he caused it. I didn't examine them that carefully when I sent them in. I will check with them and see what they will do.

Thanks! :smile:
I hadn't considered the blade itself having a slight bow in it.
If that is the case , it may as Steve said , come right when tightened into place .

Hopefully , that is all it needs
 

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Discussion Starter · #8 ·
That is worthy of consideration but I didn't see any bowing. The sharpener returns knives on a plywood board into which he has sawn grooves that hold the knives, with a couple rubber bands around them.

I called him and he said he would check and redo them and that his jig/device can go out of adjustment at times (my words on that). I was pleased with the call. So next Friday we'll know more.

Meantime, I don't have a knife-setting gauge for this planer and it doesn't look like I will be able to find one. My best measurements indicate that the cutter head on this 15" planer is 2 7/8" in diameter, which is what Powermatic/Jet has done (others use a 3" dia. cutter head). So, help me here, doesn't it make sense that one could borrow a gauge from someone with a similar machine having the same diameter cutter head to set the knives?

And the planer is missing 3 of the 6 tapered springs that push against the back side of the knives up. I've discovered that they, too, are tough to come by. I found some at the local Ace Hardware that aren't perfect but might work. Thoughts??

Thanks, all,

Chuck Barnett
 

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And the planer is missing 3 of the 6 tapered springs that push against the back side of the knives up. I've discovered that they, too, are tough to come by. I found some at the local Ace Hardware that aren't perfect but might work. Thoughts??

Thanks, all,

Chuck Barnett

You don't 'need' the springs at all... :no:

Once the blades get sharpened a LOT - The springs don't do anything anyway... They are only there to help you 'set' the blades (with the jig) but you don't 'need' them to do this.

I tighten my gib screws on the far ends of the cutterhead just enough to 'barely' hold the blades in place and then use the jig to push the blades down to where they 'need' to be... No need for the springs. The aluminum jig is NOT going to damage the blades pushing them down like this.

OR you could use magnets to 'pull' the blades up (depends on the blades and metal). Either way will work fine.

I chuck blades that are SMALLER than the gib that 'holds' them but not before then... :smile:
 

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Discussion Starter · #10 ·
I got the knives back from the sharpener with a note. He said they are within four thousanths over their total length. He said that if I needed them to be better they would need to be jointed after installed in the head. ???
 

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.004" sounds like a lot to me, but maybe it isn't. I would try them, and if you're not happy find a different sharpener (I guess). The real reason I'm typing this is to offer you a Delta jointer knife gauge. I replaced the cutterhead on my 15" Delta and still have the knife gauge. It's yours for the postage if you want it. This may have had the 3" cutterhead (don't remember), but I can't imagine that the 1/8" difference in diameter would be material. I suppose if this one is slightly tall, you might be able to trim it down some if you're careful. Anyway, though I'd offer. If you want it I'll need your address, send me a PM.
 

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Being off by .004" should be okay as the wood expansion and contraction would be more than that.

Also to note is that the blades need to be all the same size in length, width and thickness so that they all weigh the same. Having one blade a different weight will cause balancing issues and excessive bearing wear. The cutter head spins at a good rate of speed.
 
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