Anyone know what an acceptable tolerance is on planer/jointer knives? I
just sharpened 2 sets of each(dewalt 12" planer, and Jet 6" jointer) and
I weighed them just to see. There is 1.8 grams difference from heavest
to lightest on one set of jointer knives. Every thing else is closer.
Just got me to wondering...How close do they need to be? Don't need me
no bearing probs if I can help it.
Thanks for your knowledge
I'm going to guess that these are from a 3-knife head in
which case they should be the same weight (balance). With a
4-knife head you could load unequal weights as long as the
knives opposite each other were identical in weight and
balance, i.e., 1-2-1-2 in the revolution of the head.
If you would like there is a 167 page knife grinding manual
from C.G. Schmidt you can get. I suspect it would/could
also substitute for Nytol in a pinch as it goes into all
knife grinding applications.
You are right about the premature bearing wear. It is best
to do these things right the first time.
Oh, and try and realize this is all free advice (advise to
some) and worth every penny.
On Sat, 27 Sep 2003 15:46:14 -0500, Traves W. Coppock wrote:
If one was to get real teknikul about this, a bunch-o-factors could get
involved. If'n you grind off the back corners, the center of gravity
ain't in the center, making things possibly unbalanced when the blade
edges are all at exaktly the right height. In fact, a difference in
thickness could move the center of gravity on the knives even though
they are aligned properly, and even though they all weigh the same.
It all gets so confusing...
Probably need a 'puter app to really screw it up ;-)
I suppose getting REAL technicle about the balance would be a little
"over the top". I weighed the knives on a reloading powder scale. (real
accurate) The weights weren't even close. What was balanced on one
knife would bottom out hard on another. I wasn't trying to get to some
zen perfection on the knives, but it looked like "balanced" on one knife
should be close to balanced on the others. Hell, the beam on the scale
hit the top so hard on the heavy knife, I checked to see if it broke!
It was like the knife was 1/2 " longer or something.
Me and my bench grinder fixed that lard assed knife good though.
Life is good.
No, I'm gonna have to hope Jet did that for me. I just checked the
knives after sharpening cause I think that comes under user
responsibility. Thats something that will change with every sharpening.
The cutter head should be balanced from the fact. just like the knives
"should" be. I ain't gonna take the damn thing apart, just gonna make
the knives weigh the same , within reason.
Went out to the shop this morn to see what is "1.8 grams" It is basicly
a 1 1/4" #8 self drilling wood screw W/nibs. I thought that was just a
little to much. I ground the back corners off the heavy knives into a
curved radius about the same on both sides. Was surprised how much I
had to grind to get them real close. The knives came from Jet about
that far out of balance cause I haven't sharpened them but twice and
ground them evenly when I did it.( on tormec) It was probably not a
problem but I feel better now that they are real close.
So the lesson is...just because your knives are new doesn't mean they
weigh the same.
Damn boards will probably joint themselves now!!
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