A week ago, I bought a spare set of jointer knives because my original set
needs sharpening. The old knives were leaving lines on the material and not
cutting well. The new knives were just in time to straighten some soft
maple for cabinet doors. The new knives are made by Amana.

Here's what surprised me...for the first 10 boards, the cuts were smooth as
silk. I kept checking each one in amazement as to how perfect they were
coming out. Then, without realizing it, I guess I passed a board with a
small knot over the surface. After finishing the rest of the boards, the
remaining few started to show signs of knife divots, etc. I barely used
them for 30 minutes and now they're leaving knife marks (sandable but less
than perfect) on the material.

How long should freshly-sharpened knives remain "perfect" until they start
leaving some marks? Also, how many times can jointer knives (I have a
3-knife 8" jointer) be sharpened? Can a tougher knife be purchased for
jointers, something with carbide, perhaps?

30 minutes of bliss and now it's back to reality.

-m

"Mike Pio" wrote in message

How long should freshly-sharpened knives remain "perfect" until they start
leaving some marks?

Until they hit something tougher than the edge of the blade. Then they go
down hill really fast. Watch that knot in the planer

Until the firt knot?
You can offset the knifes slightly.

Mike Pio wrote:
A week ago, I bought a spare set of jointer knives because my original set
needs sharpening. The old knives were leaving lines on the material and not
cutting well. The new knives were just in time to straighten some soft
maple for cabinet doors. The new knives are made by Amana.

Here's what surprised me...for the first 10 boards, the cuts were smooth as
silk. I kept checking each one in amazement as to how perfect they were
coming out. Then, without realizing it, I guess I passed a board with a
small knot over the surface. After finishing the rest of the boards, the
remaining few started to show signs of knife divots, etc. I barely used
them for 30 minutes and now they're leaving knife marks (sandable but less
than perfect) on the material.

How long should freshly-sharpened knives remain "perfect" until they start
leaving some marks? Also, how many times can jointer knives (I have a
3-knife 8" jointer) be sharpened? Can a tougher knife be purchased for
jointers, something with carbide, perhaps?

30 minutes of bliss and now it's back to reality.

-m



When blades are sharpened the blades develop a "wire burr" on their
edge. The marks you're seeing may be the result of this wire burr being
removed by usage. Once the burr is fully removed the divots may stop.

FWIW, I don't expect a finished face/edge coming off my jointer. I only
hope the board comes off with one face flat and one edge straight. The
finish planer and sanding take care of the rest.


--
Jack Novak
Buffalo, NY - USA

(Remove -SPAM- to send email)

On Sun, 16 Oct 2005 08:07:52 -0700, "Mike Pio"
wrote:

A week ago, I bought a spare set of jointer knives because my original set
needs sharpening. The old knives were leaving lines on the material and not
cutting well. The new knives were just in time to straighten some soft
maple for cabinet doors. The new knives are made by Amana.

Here's what surprised me...for the first 10 boards, the cuts were smooth as
silk. I kept checking each one in amazement as to how perfect they were
coming out. Then, without realizing it, I guess I passed a board with a
small knot over the surface. After finishing the rest of the boards, the
remaining few started to show signs of knife divots, etc. I barely used
them for 30 minutes and now they're leaving knife marks (sandable but less
than perfect) on the material.

How long should freshly-sharpened knives remain "perfect" until they start
leaving some marks? Also, how many times can jointer knives (I have a
3-knife 8" jointer) be sharpened? Can a tougher knife be purchased for
jointers, something with carbide, perhaps?

30 minutes of bliss and now it's back to reality.

-m


I can't say what actually caused your problem, but my experience has
been that my jointer blades (HSS for an Inca) are quite a bit harder
than knots. Of course they wear eventually, but not on a single pass.
What does get them is to negligently pass a board through that has
been sitting on the ground and collected "grit". This results in
immediate feedback in the form of fine lines down the length of
subsequent stock. I usually keep an old bench brush handy and give
each new, rough, plank a thorough brushing before the first pass.

--l

Mike Pio wrote:

....
How long should freshly-sharpened knives remain "perfect" until they start
leaving some marks?

Depends on your definition of "perfect", I suppose. As someone else
noted, the pristine edge will last until something harder comes along.
I don't buy the wire edge theory.

Also, how many times can jointer knives (I have a
3-knife 8" jointer) be sharpened?

Depends on how big they are to start w/ and how much one has to take off
(obviously). I have only bought one set or replacement blades for the
8" Delta w/ the in over 30 yrs. I couldn't tell you how many times
they've been resharpened, but I make sure they're done before large
amounts of material must be removed. I also keep an old set if I know
I'm going to have to clean up some old material and take the timet to
swap them in to protect the "good" ones....

Can a tougher knife be purchased for
jointers, something with carbide, perhaps?

Solid carbide knives are available, for a price.

Here's what surprised me...for the first 10 boards, the cuts were smooth as
silk. I kept checking each one in amazement as to how perfect they were
coming out. Then, without realizing it, I guess I passed a board with a
small knot over the surface. After finishing the rest of the boards, the
remaining few started to show signs of knife divots, etc. I barely used
them for 30 minutes and now they're leaving knife marks (sandable but less
than perfect) on the material.

this seems to happen to fresh knives. seems to be the way life kicks
you in the pants (G) but shifting the knives can fix it.
I have had this happen several times right after a knife change.
Knight-Toolworks
http://www.knight-toolworks.com
affordable handmade wooden planes

When blades are sharpened the blades develop a "wire burr" on their
edge. The marks you're seeing may be the result of this wire burr being
removed by usage. Once the burr is fully removed the divots may stop.

there should be no wire burr if they are sharpened right. and even if
a burr was left the first pass would remove it.
Knight-Toolworks
http://www.knight-toolworks.com
affordable handmade wooden planes

I wonder if the knives you got are not as tuff as what you were using?
that could very well be the problem. putting a back bevel on them
would make them stronger.
Knight-Toolworks
http://www.knight-toolworks.com
affordable handmade wooden planes

Steve knight wrote:

I wonder if the knives you got are not as tuff as what you were using?
.....

I don't know, Amana stuff is usually pretty darn good---unless they've
started a "consumer" line I don't know of????

"Duane Bozarth" wrote in message
...
Steve knight wrote:

I wonder if the knives you got are not as tuff as what you were using?
....

I don't know, Amana stuff is usually pretty darn good---unless they've
started a "consumer" line I don't know of????

That's been my experience as well. The original set was stock with the
jointer (Delta DJ-20) and they lasted for several months of fairly regular
usage. I figured the Amana's would outlast them by some factor, but I guess
I was wrong.

I'm sure what happens to knives is determined by many factor, namely
material, defects, technique, etc. I just didn't think soft maple and a
knot or two should bugger them so quickly. I'll shift a knife as others
suggested to see if that fixes me. This situation is why we keep a spare
set handy -- unfortunately, this is the spare set!

-m

"Mike Pio" wrote in message
news:SHZ4f.55735$WR2.25096@fed1read03...

I'm sure what happens to knives is determined by many factor, namely
material, defects, technique, etc. I just didn't think soft maple and a
knot or two should bugger them so quickly. I'll shift a knife as others
suggested to see if that fixes me. This situation is why we keep a spare
set handy -- unfortunately, this is the spare set!


Did it occur to you that the branch may have had some time to collect sand
and such before it was overgrown?

The reason for a spare set is the surprises, not the anticipated wear as you
consistently joint all the way right on the table. That's our fault, the
other is chance.

What kind of blade material in the replacement blades you bought?

You really want HSS or Carbide if shooting for long life, HSS is
better than most non-HSS speed steel, and Carbide at the top of the
list both long lifewise as well as pricewise

John

On Sun, 16 Oct 2005 08:07:52 -0700, "Mike Pio"
wrote:

A week ago, I bought a spare set of jointer knives because my original set
needs sharpening. The old knives were leaving lines on the material and not
cutting well. The new knives were just in time to straighten some soft
maple for cabinet doors. The new knives are made by Amana.

Here's what surprised me...for the first 10 boards, the cuts were smooth as
silk. I kept checking each one in amazement as to how perfect they were
coming out. Then, without realizing it, I guess I passed a board with a
small knot over the surface. After finishing the rest of the boards, the
remaining few started to show signs of knife divots, etc. I barely used
them for 30 minutes and now they're leaving knife marks (sandable but less
than perfect) on the material.

How long should freshly-sharpened knives remain "perfect" until they start
leaving some marks? Also, how many times can jointer knives (I have a
3-knife 8" jointer) be sharpened? Can a tougher knife be purchased for
jointers, something with carbide, perhaps?

30 minutes of bliss and now it's back to reality.

-m

wrote in message
...
What kind of blade material in the replacement blades you bought?

HSS


You really want HSS or Carbide if shooting for long life, HSS is
better than most non-HSS speed steel, and Carbide at the top of the
list both long lifewise as well as pricewise

John

On Sun, 16 Oct 2005 08:07:52 -0700, "Mike Pio"
wrote:

A week ago, I bought a spare set of jointer knives because my original set
needs sharpening. The old knives were leaving lines on the material and
not
cutting well. The new knives were just in time to straighten some soft
maple for cabinet doors. The new knives are made by Amana.

Here's what surprised me...for the first 10 boards, the cuts were smooth
as
silk. I kept checking each one in amazement as to how perfect they were
coming out. Then, without realizing it, I guess I passed a board with a
small knot over the surface. After finishing the rest of the boards, the
remaining few started to show signs of knife divots, etc. I barely used
them for 30 minutes and now they're leaving knife marks (sandable but less
than perfect) on the material.

How long should freshly-sharpened knives remain "perfect" until they start
leaving some marks? Also, how many times can jointer knives (I have a
3-knife 8" jointer) be sharpened? Can a tougher knife be purchased for
jointers, something with carbide, perhaps?

30 minutes of bliss and now it's back to reality.

-m

"George" George@least wrote in message
...

"Mike Pio" wrote in message
news:SHZ4f.55735$WR2.25096@fed1read03...

I'm sure what happens to knives is determined by many factor, namely
material, defects, technique, etc. I just didn't think soft maple and a
knot or two should bugger them so quickly. I'll shift a knife as others
suggested to see if that fixes me. This situation is why we keep a spare
set handy -- unfortunately, this is the spare set!


Did it occur to you that the branch may have had some time to collect sand
and such before it was overgrown?

Nope, never thought of that. Didn't even realize it was a possibility.


The reason for a spare set is the surprises, not the anticipated wear as
you consistently joint all the way right on the table. That's our fault,
the other is chance.

On Tue, 18 Oct 2005 13:43:53 -0500, wrote:

What kind of blade material in the replacement blades you bought?

You really want HSS or Carbide if shooting for long life, HSS is
better than most non-HSS speed steel, and Carbide at the top of the
list both long lifewise as well as pricewise

solid carbide is not always a good idea on jointer knives. it can be
too brittle.
the best of life is a helical carbide cutter head. most normal
woodworkers may go a year or more before rotating the knives.
Knight-Toolworks
http://www.knight-toolworks.com
affordable handmade wooden planes