Update on adjusting jointer knives

I fooled with that thing for several hours. I have two blades adjusted to about .002 above outfeed table. One blade is at 0. SHould I try to get that last blade to .002 also or knock down the two at .002 to zero. It is very hard to get everything exactly the same on three blades.
Or will the difference be negligible the way it is?
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Seems to me that adjusting one blade to match the other two would be easier than adusting two blades to match one....
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It is just people on here some say to adjust to .002 over the outfeed table to account for blade wear and deflection. SOme say it must be exactly 0 or you will not get a level cut. Just a little confused. Locutus wrote:

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--top posting repaired--
stryped wrote:

Why not give it a go and see how it works? Might find it "good enough".
In general must agree w/ Locutus it's easier to fiddle w/ one than two...I reiterate previous recommendation that w/o the adjusting screws it will undoubtedly by easier if you've tightened them down to bring the one back up a little high and tap it in than get it out by only a thou or two.
The thing about the height relative to the outfeed table is, yet again, the point in having the height adjusting screws on the cutterhead itself. Get the knives consistent, then make some test cuts and, if and only if needed, then adjust the cutterhead height. Again, this is how the manual instructs.
Reiterate yet again, however...woodworking isn't machining, and obsessing over precision isn't productive. The point in having the machine should be to use it (although there are those who seemingly never do get around to actually ever making sawdust---you may be one. Whether that's your objective, I don't know).
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stryped wrote:

hey, go for it. get them all the same.
now, whether your machine will cut straighter at 0 or at +.002 only you can determine, and only by careful testing. so, with the machine as it is, make a pass on a known straight board. label it 0,+.002,+.002. then adjust the 0 blade to +.002, make a pass on a known straight board and label it +.002,+.002,+.002. then set them all to 0, make a pass on a known straight board and label it 0,0,0. for significant results, you will probably need to make multiple samples at each setting to average out for variations in the stability and density of your boards. also,make boards of different lengths....
now set up an accurate test station to determine straightness. if you get meaningful results, including things like (no difference),(high blades cut concave),(high blades cut straight),(low blades cut convex),(low blades cut straight),(other), let us know.
now, go get going, now....
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snipped-for-privacy@yahoo.com wrote:

LOL!!! That's just plain mean :-)
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Dave
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stryped wrote:

Rather than go for "ideal/perfect", run a few boards with the set up you have. If the results look good to you then you're done. If not, THEN adjust the one that's 0.002" off the other two.
Keep in mind that the joiner and planer are for creating reference surfaces and edges for subsequent parts making. Glass smooth edges and surfaces aren't necessary. And while making and assembling parts, your going to get smudges, pencil marks and stuff on the surfaces which you'll remove later with sand paper and/or scrapers.
Realize that 0.002" is less than 1/256ths of an inch. After you run 20 or 30 feet of stuff the 0.002" high knife edges will probably be closer to the Zero knife anyway.
While it's good to know if your machines are set up correctly, and assuming an out of ideal specs isn't dangerous, it's the results that are important - not the theoretical perfection.
Don't sweat the small stuff unless they significantly affect the big stuff.
charlie b
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charlie b wrote: After

What type of wood are you running though your jointer that takes off 2 thou in 30 feet?
Dave
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stryped wrote:

Negligible? Depends...2 blades will be taking off 1/500 (plus or minus) more than the third. Is 1/500 of an inch significant with wood? Not to me...
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dadiOH
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The jointer is used for two operations.....jointing edges, which is easy and leveling boards which requires precision setting of the knives. I learned this when I tried to flatten a badly warped piece of maple. It made edges straight as can be but the warp got worse the more times I put the piece through the jointer. I then set the blades exactly all the same and level with the outlet table. The board suddenly got flatter and flatter with each pass. Dave

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