I have the tools needed to sharpen jointer knives with either:
1) a flat surface
2) a hollow ground surface

Which type of grind would YOU choose and why?


Gary

I think hollow grinding would weaken the point too much in this application.

Walt Conner

In article .com, wrote:
I have the tools needed to sharpen jointer knives with either:
1) a flat surface
2) a hollow ground surface

Which type of grind would YOU choose and why?

I'd choose whichever one I could do faster. For me, that's hollow-ground,
because I already have a Tormek grinder with the appropriate jigs.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

On 28 Mar 2007 11:35:28 -0700, wrote:

I have the tools needed to sharpen jointer knives with either:
1) a flat surface
2) a hollow ground surface

Which type of grind would YOU choose and why?


Gary


I use a waterstone and a jig. A hollow ground surface does not make
sense.

In article rYzOh.5647$Qi2.4001@trndny07, "WConner" wrote:
I think hollow grinding would weaken the point too much in this application.

You must be using a *very* tiny grinding wheel. :-)

My jointer knives are ground at an angle such that the bevel measures about
0.16" wide. I hollow-grind them on a Tormek grinder with a 10"-diameter wheel.
The difference between the hollow-ground curve and a straight line calculates
to 0.00064" maximum.

I haven't noticed any particular problems with weak edges...

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

wrote in message
oups.com...
I have the tools needed to sharpen jointer knives with either:
1) a flat surface
2) a hollow ground surface

Which type of grind would YOU choose and why?


Gary


I believe hollow ground would be a wasted effort. The grind would be on the
wrong side of the knife edge to be of any value. Typically the hollow grind
is on the side of the edge that cuts away the shavings.

SWDeveloper wrote:
On 28 Mar 2007 11:35:28 -0700, wrote:


I have the tools needed to sharpen jointer knives with either:
1) a flat surface
2) a hollow ground surface

Which type of grind would YOU choose and why?


Gary



I use a waterstone and a jig. A hollow ground surface does not make
sense.
Hollow-grinding would probably give a better finish, for a much shorter
period of time. Hollow-grinding removes much of the support directly
behind the cutting edge, making it much more vulnerable to dulling quickly.

__ Bøb __

I don't believe there would be any added benefit of flat vs. hollow, so
choose the one that is the easiest and most repeatable for you. Personally,
I use a Tormek and jig (which produces a slight hollow grind) and have been
happy with that. --dave



wrote in message
oups.com...
I have the tools needed to sharpen jointer knives with either:
1) a flat surface
2) a hollow ground surface

Which type of grind would YOU choose and why?


Gary

"Leon" writes:

wrote in message
roups.com...
I have the tools needed to sharpen jointer knives with either:
1) a flat surface
2) a hollow ground surface

Which type of grind would YOU choose and why?


Gary


I believe hollow ground would be a wasted effort. The grind would be on the
wrong side of the knife edge to be of any value. Typically the hollow grind
is on the side of the edge that cuts away the shavings.



The sole purpose of a hollow grind is to make honing faster because one
doesn't need to remove the material in the hollow. A hollow grind makes little
difference to cutting performance.

scott

" Hollow-grinding removes much of the support directly
behind the cutting edge, making it much more vulnerable to dulling quickly."

You said what I was trying to but much better.

Walt Conner

"Scott Lurndal" wrote in message
. net...
"Leon" writes:





The sole purpose of a hollow grind is to make honing faster because one
doesn't need to remove the material in the hollow. A hollow grind makes
little
difference to cutting performance.


Scott, you do not know what you are talking about. If you want to speed up
honing an edge simply increase the angel of the micro bevel on the edge.
A hollow grind creates a concave surface below the cutting edge. The
hollow spot reduces friction against the shaving after it has been cut and
that air gap makes the cut easier and smoother.
Some old style circle saw blades were hollow ground for smoother cuts. That
in no way helped to hone teeth. My pocket knife is hollow ground about
1/16" below the cutting edge. I would have to remove 1/16" of steel to make
honing the edge easier or to reach the beginning of the hollow grind.

Do some studying.

"Scott Lurndal" wrote in message
. net...

I believe hollow ground would be a wasted effort. The grind would be on
the
wrong side of the knife edge to be of any value. Typically the hollow
grind
is on the side of the edge that cuts away the shavings.



The sole purpose of a hollow grind is to make honing faster because one
doesn't need to remove the material in the hollow. A hollow grind makes
little
difference to cutting performance.

scott


At the risk of wasting my time , I gathered information for you again.
Study or remain ignorant.
I got this information from the top of a Google search.

http://www.sff.net/people/pff/blade.txt

III. Blade Grinds

- The Hollow Grind

The hollow grind is done by taking two concave scoops out of the side
of the blade. Many production companies use this grind, because it's
easier to design machines to do it. But many custom makers grind this
way as well. Its great advantage is that the edge is extraordinarily
thin, and thin edges slice better. The disadvantage is that the
thinner the edge, the weaker it is. Hollow ground edges can chip or
roll over in harder use. And the hollow ground edge can't penetrate
too far for food-type chopping, because the edge gets non-linearly
thicker as it nears the spine.

For designs where slicing is important, but the slice doesn't need to
go too deep, this grind is an excellent choice. Many hunting knives
are hollow ground, because field dressing is often best done with a
knife that slices exceptionally well through soft tissues.
Unfortunately, if you hit a bone, you can chip the edge, so the flat
grind (see below) is also used often.

Another advantage of the hollow ground knife, at least at the
beginning, is ease of sharpening. Most hollow grinds thicken slightly
towards the edge. That means that as you sharpen (at least at first),
the blade gets thinner and easier to sharpen. After this, however,
the blade begins thickening non-linearly and sharpening will become
more difficult.

The ultimate push cutter, the straight razor, is usually hollow
ground.

Leon wrote:
"Scott Lurndal" wrote in message
. net...

I believe hollow ground would be a wasted effort. The grind would be on
the
wrong side of the knife edge to be of any value. Typically the hollow
grind
is on the side of the edge that cuts away the shavings.



The sole purpose of a hollow grind is to make honing faster because one
doesn't need to remove the material in the hollow. A hollow grind makes
little
difference to cutting performance.

scott



At the risk of wasting my time , I gathered information for you again.
Study or remain ignorant.
I got this information from the top of a Google search.

http://www.sff.net/people/pff/blade.txt

III. Blade Grinds

- The Hollow Grind

The hollow grind is done by taking two concave scoops out of the side
of the blade. Many production companies use this grind, because it's
easier to design machines to do it. But many custom makers grind this
way as well. Its great advantage is that the edge is extraordinarily
thin, and thin edges slice better. The disadvantage is that the
thinner the edge, the weaker it is. Hollow ground edges can chip or
roll over in harder use. And the hollow ground edge can't penetrate
too far for food-type chopping, because the edge gets non-linearly
thicker as it nears the spine.

For designs where slicing is important, but the slice doesn't need to
go too deep, this grind is an excellent choice. Many hunting knives
are hollow ground, because field dressing is often best done with a
knife that slices exceptionally well through soft tissues.
Unfortunately, if you hit a bone, you can chip the edge, so the flat
grind (see below) is also used often.

Another advantage of the hollow ground knife, at least at the
beginning, is ease of sharpening. Most hollow grinds thicken slightly
towards the edge. That means that as you sharpen (at least at first),
the blade gets thinner and easier to sharpen. After this, however,
the blade begins thickening non-linearly and sharpening will become
more difficult.

The ultimate push cutter, the straight razor, is usually hollow
ground.


Pretty much an expanded version of what I said .. .. .. but he ignored
me too !! !! !!

hehehehe !!

"Leon" wrote in message
t...

"Scott Lurndal" wrote in message
. net...

I believe hollow ground would be a wasted effort. The grind would be on
the
wrong side of the knife edge to be of any value. Typically the hollow
grind
is on the side of the edge that cuts away the shavings.



The sole purpose of a hollow grind is to make honing faster because one
doesn't need to remove the material in the hollow. A hollow grind makes
little
difference to cutting performance.

scott


At the risk of wasting my time , I gathered information for you again.
Study or remain ignorant.

Since either will be produced under machine power, makes no time or
convenience difference if hollow or flat. Takes longer to set up a grinder
and jig than to freshen the blades with it. Other than laying the knife
flat on it to clear any wire edge (which will clear anyway), a stone is
superfluous.

So why not take the tad bit extra durability in the flat-ground edge.
Unless you spent your bucks for a Tormek, of course.

In article Q3FOh.9292$fA2.3209@trndny02, "WConner" wrote:
" Hollow-grinding removes much of the support directly
behind the cutting edge, making it much more vulnerable to dulling quickly."

You said what I was trying to but much better.

Well, yeah, but on a jointer knife, the ground edge is so narrow that it
doesn't make any difference at all.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

"George" wrote in message
et...

Since either will be produced under machine power, makes no time or
convenience difference if hollow or flat. Takes longer to set up a
grinder and jig than to freshen the blades with it. Other than laying the
knife flat on it to clear any wire edge (which will clear anyway), a stone
is superfluous.

So why not take the tad bit extra durability in the flat-ground edge.
Unless you spent your bucks for a Tormek, of course.

Agreed, which is basically what I said. Basically the hollow grind on the
jointer knife would not be utilized at all. But then there was the comment
that the sole purpose of the hollow grind was speed honing, which was a
shoot from the hip BS statement.