Another one to play with....


NT


Sharpen cutlery


Sharp kitchen knives make hard jobs easy, reduce fatigue, and reduce
the risk of accident due to putting too much force on a knife and
losing control.


==Considerations==
===Metals===
The quality of steel used in knives varies fairly widely. Some knives
can take a very sharp edge, most can be made fairly sharp, and the
occasional bad one is barely capable of becoming sharp at all.


===Angles===
Specific angles are best for specific metals and jobs, but with
kitchen knives one is usually working with unknown budget metal, and
not looking for a razor edge. The thinner the angle, the more sharp
the blade is initially, but the quicker it blunts. And with popular
low cost cutlery, blunting at narrow angles can be very quick. Also
the poorest quality metal, found on some table knives, is sometimes
unable to take 35 degrees without the cutting edge pitting during
grinding.

The following angles work well for me:

Cutting knives: 30 degrees.
* sharp
* blunts quickly if used with glass boards or ceramic plates

Table knives: 40 degrees
* mildly sharp
* child friendly
* works on any steel
* retains its mildly sharp edge well
* Not very sharp, but a big improvement on a blunt knife.

Its possible to place a printed angle under the grinder to act as a
guide if wanted. Personally I don't lose sleep over precision here,
kitchen knives are far from critical high performance tools. If you
buy high cost knives, you should follow the original grinding angles
to ensure you get the best possible performance. Most people however
are working with unknown material, and its not possible to specify
what angle will give the best performance for each knife.

If you're determined to tweak your grinding angles to get peak
performance out of each knife, it may be worth nothing that in my
experience the worst quality metal is found not on cheapo knives, but
on pretty table knives from a popular major manufacturer, one most
buyers would regard as quality.


==Serrated blades==
Serration is a way to get much of the effect of sharpness without real
sharpness being present. Serration is widely disliked among knife
sharpeners, but its an easy way to get cutting ability from cheap
metal, its liked by many end users, and it has its uses, such as
cutting frozen food. Consequently it may be wished to sharpen serrated
knives without loss of serration.

There's no easy way to maintain the serrated shape indefinitely while
sharpening using home equipment. There are however a few successful
ways to sharpen serrated knives.


===Sharpen the back===
Often knives are serrated asymmetrically, with serrations ground on
one side only. In this case the flat other side of the blade can be
ground. Only a small amount of grinding is needed. A final single very
light pass on the serrated side removes any burr.


===Sharpen the tips===
Where the above method doesn't produce enough sharpening, the knife
may be ground on the serrated side(s) too. The idea here is not to
thoroughly grind all areas of the blade, but rather to make the usual
fairly quick pass over the blade. This will sharpen the tips only,
giving a big improvement in performance. Its good enough for most
uses.


===Rough edge===
This technique produces a rough edge with mini serrations, and works
well with an angle grinder. I don't know if its possible to do this
approach with other grinding tools. The blade is sharpened as normal,
but its moved over the grinder disc as quickly as can be done safely,
rather than gradually. The idea is to pass the whole length of the
blade over the disc in about half a second. The result is fairly
sharp, but rough and uneven. It effectively creates ungraceful
serrations. A rough old grinding disc creates more serration than a
new smooth one.

This method isn't often the best choice, but can be used where
existing serrations are too uneven to sharpen usefully, and where
conversion to a plain edge is unworkable for some reason, eg not
enough metal left, or would require grinding an excessive amount of
metal away. Its also a very quick way to deal with serrated knifes
that are barely worth the trouble of sharpening.


===Sharpen all===
In principle its possible to sharpen cresent shaped serrations and
maintain their shape. However its very time consuming and not very
pointful, so not normally done.


===Plain blade conversion===
The final option is to remove enough metal to convert the knife to a
plain blade. This is usually not necessary, but is the only way to
ensure a blade that's sharp every millimetre of its length.


==One sided blades==
Many knives come ground on one side only. This causes them to wander
off line when cutting, which is a pain in the kitchen. Its a good idea
to grind them on the unground side to reduce this tendency, only
making a final burr removing pass on the originally ground side.


==Sharpening tools==
There are a few ways to sharpen kitchen blades.

===Kitchen knife sharpener===
Many low cost motorised domestic knife sharpeners are available. One
go with one of these caused me to abandon all hope.


===Bench grinder===
Bench grinders are the best option in most respects. They are the
standard engineer's choice for sharpening a wide range of blades. They
don't look particularly graceful in the kitchen though. They also lack
the speed of an angle grinder.


===Block===
Manual sharpening is slow, and stock removal even slower. Nevertheless
some people prefer this approach.


===Steel===
A traditional steel doesn't grind. Rather it restores a
microscopically bent cutting edge by restraightening it. These were
used between sharpenings as an intermediate way to prolong sharpness.

Modern performance knives don't use steel that suffers this fate, so a
steel isn't much use with them. However cheaper knives do use softer
metal, and may benefit from use of a steel.


===Abrasive Steel===
The abrasive steel is a traditional steel but with some added
abrasive. It primarily acts like a traditional steel, but also
provides a little grinding as well, thus prolonging sharpening
intervals further. However hand powered grinding of any sort is a
labour intensive way to sharpen knives compared to machine grinding.


===Sandpaper===
Sandpaper may be used on a dead flat surface (eg glass) for
sharpening. This has popularly become known as the 'scary sharp'
method, as by progressing through increasingly fine grades its
possible to achieve a very high level of sharpness.


===Angle grinder===
The suggestion of using an [[angle grinder]] to sharpen knives often
raises eyebrows. However they are very fast and effective, able to
sharpen a totally blunt knife in 20-30 seconds, and remove stock to
create a new edge in under a minute. This speed makes it easy and
practical to sharpen all one's knives quickly, table knives included.
For busy people this is a real advantage.

====Flaws====
As sharpeners, angle grinders have some sizeable flaws, and some
precautions are very necessary.

The knife blade must be kept moving, don't ever grind one stationary
spot. Doing so would overheat the metal in 5-10 seconds, and if this
happens the blade will never be able to keep an edge again.

The very high disc speed can throw a knife if held to the disc in the
wrong direction. Always confirm the direction of rotation before use
(eg with a match etc), and take care to hold the knife the right way.

Always use indirect vent goggles, ear defenders, and ideally a full
face mask too.

Never use a damp grit disc in an angle grinder, and don't dip cutlery
in water to cool it when using such a disc. Damp grit discs can fail
violently.

Keep your face out of the plane of rotation of the disc. Grit discs
can break violently.

Angle grinder grit discs are somewhat coarse. This coarseness limits
the level of sharpness available, but the result is plenty sharp
enough for any normal kitchen use. It would not satisfy most die hard
knife sharpeners though. Use only the very lightest pressure to
achieve the sharpest edge.

Don't use these tools if tired, drunk, drugged, or not really with it.
They aren't a nice friendly power tool.


====Use====
If you have an angle grinder stand, use it. If not, the tool may be
held on its back to minimise fatigue. Sitting down with it on your
knees (in your hand of course) makes it easy to pass knives both ways.
However you position it, keep a good firm grip at all times.

To sharpen, move the blade as shown past the disc. Use the lightest of
pressure only. 2 strokes on each side of the blade is enough for any
blade that already has an edge formed, ie doesn't need stock removal.
Finally make a burr removing pass along the other side of the blade
(compared to the previous stroke). Use all the pressure of a feather,
so the blade only just barely touches the disc.

Stock removal requires just a little pressure, and more passes. Never
get the metal hot though, if in any doubt just put the knife down and
come back to it a bit later. Dipping the knife in water is not
recommended with grit discs, damp can cause violent disc failure.


===Die grinder===

==After grinding==
Knives should always be washed after grinding. Grind stones can
harbour all sorts of detritus, oil residues, decayed food & so on.

Its also worth warning the rest of the household if previously blunt
knives are now psychopathically sharp.


==Care of sharp knives==
Use of 30 degree knives on glass chopping boards or ceramic plates
blunts them quickly. Most knife sharpeners prefer wooden chopping
boards.

Knives with relatively soft steel benefit from use of a steel between
sharpenings.


==Still to do==
Stainful steel: pre-ss knives are occasionally seen, but I know
nothing about their sharpening characteristics.


==See Also==
* [[Knives]]
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]



[[Category:
[[Category:

wrote in message
...
Another one to play with....


NT


Sharpen cutlery


snip


Need to add to sharpening methods

http://www.dmtsharp.com/


I have sharpened some serrated knives with a chainsaw file... slow but
effective

Sandpaper is for budgies cages or so my old woodwork teacher used to say. He
preferred the term glass paper

whichever not for metal

Emery paper or emery cloth for metal

also add ceramic knives

wrote in message
...
Sharpen cutlery
[BIG SNIP]
==Sharpening tools==
There are a few ways to sharpen kitchen blades.

===Kitchen knife sharpener===
Many low cost motorised domestic knife sharpeners are available. One
go with one of these caused me to abandon all hope.


===Bench grinder===
Bench grinders are the best option in most respects. They are the
standard engineer's choice for sharpening a wide range of blades. They
don't look particularly graceful in the kitchen though. They also lack
the speed of an angle grinder.


===Block===
Manual sharpening is slow, and stock removal even slower. Nevertheless
some people prefer this approach.


===Steel===
A traditional steel doesn't grind. Rather it restores a
microscopically bent cutting edge by restraightening it. These were
used between sharpenings as an intermediate way to prolong sharpness.

Modern performance knives don't use steel that suffers this fate, so a
steel isn't much use with them. However cheaper knives do use softer
metal, and may benefit from use of a steel.


===Abrasive Steel===
The abrasive steel is a traditional steel but with some added
abrasive. It primarily acts like a traditional steel, but also
provides a little grinding as well, thus prolonging sharpening
intervals further. However hand powered grinding of any sort is a
labour intensive way to sharpen knives compared to machine grinding.


===Sandpaper===
Sandpaper may be used on a dead flat surface (eg glass) for
sharpening. This has popularly become known as the 'scary sharp'
method, as by progressing through increasingly fine grades its
possible to achieve a very high level of sharpness.


===Angle grinder===
The suggestion of using an [[angle grinder]] to sharpen knives often
raises eyebrows. However they are very fast and effective, able to
sharpen a totally blunt knife in 20-30 seconds, and remove stock to
create a new edge in under a minute. This speed makes it easy and
practical to sharpen all one's knives quickly, table knives included.
For busy people this is a real advantage.

====Flaws====
As sharpeners, angle grinders have some sizeable flaws, and some
precautions are very necessary.

The knife blade must be kept moving, don't ever grind one stationary
spot. Doing so would overheat the metal in 5-10 seconds, and if this
happens the blade will never be able to keep an edge again.

The very high disc speed can throw a knife if held to the disc in the
wrong direction. Always confirm the direction of rotation before use
(eg with a match etc), and take care to hold the knife the right way.

Always use indirect vent goggles, ear defenders, and ideally a full
face mask too.

Never use a damp grit disc in an angle grinder, and don't dip cutlery
in water to cool it when using such a disc. Damp grit discs can fail
violently.

Keep your face out of the plane of rotation of the disc. Grit discs
can break violently.

Angle grinder grit discs are somewhat coarse. This coarseness limits
the level of sharpness available, but the result is plenty sharp
enough for any normal kitchen use. It would not satisfy most die hard
knife sharpeners though. Use only the very lightest pressure to
achieve the sharpest edge.

Don't use these tools if tired, drunk, drugged, or not really with it.
They aren't a nice friendly power tool.


====Use====
If you have an angle grinder stand, use it. If not, the tool may be
held on its back to minimise fatigue. Sitting down with it on your
knees (in your hand of course) makes it easy to pass knives both ways.
However you position it, keep a good firm grip at all times.

To sharpen, move the blade as shown past the disc. Use the lightest of
pressure only. 2 strokes on each side of the blade is enough for any
blade that already has an edge formed, ie doesn't need stock removal.
Finally make a burr removing pass along the other side of the blade
(compared to the previous stroke). Use all the pressure of a feather,
so the blade only just barely touches the disc.

Stock removal requires just a little pressure, and more passes. Never
get the metal hot though, if in any doubt just put the knife down and
come back to it a bit later. Dipping the knife in water is not
recommended with grit discs, damp can cause violent disc failure.


===Die grinder===

==After grinding==
Knives should always be washed after grinding. Grind stones can
harbour all sorts of detritus, oil residues, decayed food & so on.

Its also worth warning the rest of the household if previously blunt
knives are now psychopathically sharp.


I sharpen most things with a B&D powerfile and it's very effective. If
you've not come across this tool before it's like a belt sander but the
belts are only 12mm (IIRC) wide. It allows me more control than my angle
grinder and is a *lot* safer as the belt is significantly slower and the
energy much less. It can be used one-handed quite safely so I usually just
hold the knife against a stop with the blade protruding over the edge of the
workbench and run the powerfile over it judging the angle by eye. Simple,
safe and effective.

On Apr 15, 2:03*am, wrote:
Another one to play with....

NT

Sharpen cutlery

Sharp kitchen knives make hard jobs easy, reduce fatigue, and reduce
the risk of accident due to putting too much force on a knife and
losing control.

==Considerations==
===Metals===
The quality of steel used in knives varies fairly widely. Some knives
can take a very sharp edge, most can be made fairly sharp, and the
occasional bad one is barely capable of becoming sharp at all.

===Angles===
Specific angles are best for specific metals and jobs, but with
kitchen knives one is usually working with unknown budget metal, and
not looking for a razor edge. The thinner the angle, the more sharp
the blade is initially, but the quicker it blunts. And with popular
low cost cutlery, blunting at narrow angles can be very quick. Also
the poorest quality metal, found on some table knives, is sometimes
unable to take 35 degrees without the cutting edge pitting during
grinding.

The following angles work well for me:

Cutting knives: 30 degrees.
* sharp
* blunts quickly if used with glass boards or ceramic plates

Table knives: 40 degrees
* mildly sharp
* child friendly
* works on any steel
* retains its mildly sharp edge well
* Not very sharp, but a big improvement on a blunt knife.

Its possible to place a printed angle under the grinder to act as a
guide if wanted. Personally I don't lose sleep over precision here,
kitchen knives are far from critical high performance tools. If you
buy high cost knives, you should follow the original grinding angles
to ensure you get the best possible performance. Most people however
are working with unknown material, and its not possible to specify
what angle will give the best performance for each knife.

If you're determined to tweak your grinding angles to get peak
performance out of each knife, it may be worth nothing that in my
experience the worst quality metal is found not on cheapo knives, but
on pretty table knives from a popular major manufacturer, one most
buyers would regard as quality.

==Serrated blades==
Serration is a way to get much of the effect of sharpness without real
sharpness being present. Serration is widely disliked among knife
sharpeners, but its an easy way to get cutting ability from cheap
metal, its liked by many end users, and it has its uses, such as
cutting frozen food. Consequently it may be wished to sharpen serrated
knives without loss of serration.

There's no easy way to maintain the serrated shape indefinitely while
sharpening using home equipment. There are however a few successful
ways to sharpen serrated knives.

===Sharpen the back===
Often knives are serrated asymmetrically, with serrations ground on
one side only. In this case the flat other side of the blade can be
ground. Only a small amount of grinding is needed. A final single very
light pass on the serrated side removes any burr.

===Sharpen the tips===
Where the above method doesn't produce enough sharpening, the knife
may be ground on the serrated side(s) too. The idea here is not to
thoroughly grind all areas of the blade, but rather to make the usual
fairly quick pass over the blade. This will sharpen the tips only,
giving a big improvement in performance. Its good enough for most
uses.

===Rough edge===
This technique produces a rough edge with mini serrations, and works
well with an angle grinder. I don't know if its possible to do this
approach with other grinding tools. The blade is sharpened as normal,
but its moved over the grinder disc as quickly as can be done safely,
rather than gradually. The idea is to pass the whole length of the
blade over the disc in about half a second. The result is fairly
sharp, but rough and uneven. It effectively creates ungraceful
serrations. A rough old grinding disc creates more serration than a
new smooth one.

This method isn't often the best choice, but can be used where
existing serrations are too uneven to sharpen usefully, and where
conversion to a plain edge is unworkable for some reason, eg not
enough metal left, or would require grinding an excessive amount of
metal away. Its also a very quick way to deal with serrated knifes
that are barely worth the trouble of sharpening.

===Sharpen all===
In principle its possible to sharpen cresent shaped serrations and
maintain their shape. However its very time consuming and not very
pointful, so not normally done.

===Plain blade conversion===
The final option is to remove enough metal to convert the knife to a
plain blade. This is usually not necessary, but is the only way to
ensure a blade that's sharp every millimetre of its length.

==One sided blades==
Many knives come ground on one side only. This causes them to wander
off line when cutting, which is a pain in the kitchen. Its a good idea
to grind them on the unground side to reduce this tendency, only
making a final burr removing pass on the originally ground side.

==Sharpening tools==
There are a few ways to sharpen kitchen blades.

===Kitchen knife sharpener===
Many low cost motorised domestic knife sharpeners are available. One
go with one of these caused me to abandon all hope.

===Bench grinder===
Bench grinders are the best option in most respects. They are the
standard engineer's choice for sharpening a wide range of blades. They
don't look particularly graceful in the kitchen though. They also lack
the speed of an angle grinder.

===Block===
Manual sharpening is slow, and stock removal even slower. Nevertheless
some people prefer this approach.

===Steel===
A traditional steel doesn't grind. Rather it restores a
microscopically bent cutting edge by restraightening it. These were
used between sharpenings as an intermediate way to prolong sharpness.

Modern performance knives don't use steel that suffers this fate, so a
steel isn't much use with them. However cheaper knives do use softer
metal, and may benefit from use of a steel.

===Abrasive Steel===
The abrasive steel is a traditional steel but with some added
abrasive. It primarily acts like a traditional steel, but also
provides a little grinding as well, thus prolonging sharpening
intervals further. However hand powered grinding of any sort is a
labour intensive way to sharpen knives compared to machine grinding.

===Sandpaper===
Sandpaper may be used on a dead flat surface (eg glass) for
sharpening. This has popularly become known as the 'scary sharp'
method, as by progressing through increasingly fine grades its
possible to achieve a very high level of sharpness.

===Angle grinder===
The suggestion of using an [[angle grinder]] to sharpen knives often
raises eyebrows. However they are very fast and effective, able to
sharpen a totally blunt knife in 20-30 seconds, and remove stock to
create a new edge in under a minute. This speed makes it easy and
practical to sharpen all one's knives quickly, table knives included.
For busy people this is a real advantage.

====Flaws====
As sharpeners, angle grinders have some sizeable flaws, and some
precautions are very necessary.

The knife blade must be kept moving, don't ever grind one stationary
spot. Doing so would overheat the metal in 5-10 seconds, and if this
happens the blade will never be able to keep an edge again.

The very high disc speed can throw a knife if held to the disc in the
wrong direction. Always confirm the direction of rotation before use
(eg with a match etc), and take care to hold the knife the right way.

Always use indirect vent goggles, ear defenders, and ideally a full
face mask too.

Never use a damp grit disc in an angle grinder, and don't dip cutlery
in water to cool it when using such a disc. Damp grit discs can fail
violently.

Keep your face out of the plane of rotation of the disc. Grit discs
can break violently.

Angle grinder grit discs are somewhat coarse. This coarseness limits
the level of sharpness available, but the result is plenty sharp
enough for any normal kitchen use. It would not satisfy most die hard
knife sharpeners though. Use only the very lightest pressure to
achieve the sharpest edge.

Don't use these tools if tired, drunk, drugged, or not really with it.
They aren't a nice friendly power tool.

====Use====
If you have an angle grinder stand, use it. If not, the tool may be
held on its back to minimise fatigue. Sitting down with it on your
knees (in your hand of course) makes it easy to pass knives both ways.
However you position it, keep a good firm grip at all times.

To sharpen, move the blade as shown past the disc. Use the lightest of
pressure only. 2 strokes on each side of the blade is enough for any
blade that already has an edge formed, ie doesn't need stock removal.
Finally make a burr removing pass along the other side of the blade
(compared to the previous stroke). Use all the pressure of a feather,
so the blade only just barely touches the disc.

Stock removal requires just a little pressure, and more passes. Never
get the metal hot though, if in any doubt just put the knife down and
come back to it a bit later. Dipping the knife in water is not
recommended with grit discs, damp can cause violent disc failure.

===Die grinder===

==After grinding==
Knives should always be washed after grinding. Grind stones can
harbour all sorts of detritus, oil residues, decayed food & so on.

Its also worth warning the rest of the household if previously blunt
knives are now psychopathically sharp.

==Care of sharp knives==
Use of 30 degree knives on glass chopping boards or ceramic plates
blunts them quickly. Most knife sharpeners prefer wooden chopping
boards.

Knives with relatively soft steel benefit from use of a steel between
sharpenings.

==Still to do==
Stainful steel: pre-ss knives are occasionally seen, but I know
nothing about their sharpening characteristics.

==See Also==
* [[Knives]]
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]

[[Category:
[[Category:

What about more "traditional" methods such as oilstones / whetstones
etc?

Matt

These are the experiences of a long-term cook whose two sons are cooks,
one currently as a job and the other having done so part-time.

You need to add diamond sharpeners, and the devices that have tiny
wetted stones in them, sold for the trade.

Many people use steel-shaped sharpeners that have diamonds in them. I
prefer a flat plate with embedded diamonds such as are sold for
sharpening tools. One of my sons swears by the wet stone device. I have
used a very fine Global flat stone that had to be wetted. It was
excellent but *very* expensive and it wore away quickly.

I think you should differentiate bewteen sharpening and grinding or
regrinding. Sharpening is putting a fine edge back on a knife using a
steel, stone or diamond. When a knife has been sharpened many times the
edge is worn back to the thicker material and a fine edge can't be made.
At this point you either throw the knife away or have the whole of one
flat surface ground away to thin it.

Another point. You usually hone the front face with a few strokes, then
the rear face with a few and then back the front again. Not quite sure
why but this is general 'good advice' given in the trade. Ratio of two
to one, front to back.

What knives do I use? Mostly Globals because of the shape, weight and
steel quality. A large cook's knife and a small paring knife get most
use. For general paring I love the cheapo plastic handled knives. Oh,
and a Chinese cleaver for some work. I went to a master class given by a
leading Shanghai chef. He used only a cleaver but did amazing things
with it. He cut a chunk of carp and then scored it deeply down from the
cut face several times. He then turned it ninety degrees and scored
deeply again. He put the piece scored side up in hot oil and it opened
up like a chrysanthemum. Chrysanthemum Carp.

Good start though and an excellent idea. I don't know how most people
can use the rubbish knives they have, and don't sharpen properly.


Peter Scott

On Wed, 15 Apr 2009 13:01:24 +0100, Peter Scott wrote:

Another point. You usually hone the front face with a few strokes, then
the rear face with a few and then back the front again. Not quite sure
why but this is general 'good advice' given in the trade. Ratio of two
to one, front to back.

I think it's so that there isn't a minute burr turned over to one side -
ISTR looking at a knife after sharpening 1 side and, under a low-powered
microscope, there was a bit to 1 side.
--
Peter.
You don't understand Newton's Third Law of Motion?
It's not rocket science, you know.

Peter Scott wrote:

I've added most of the info so far. Few questions though...


I think you should differentiate bewteen sharpening and grinding or
regrinding. Sharpening is putting a fine edge back on a knife using a
steel, stone or diamond. When a knife has been sharpened many times the
edge is worn back to the thicker material and a fine edge can't be made.
At this point you either throw the knife away or have the whole of one
flat surface ground away to thin it.

sharpening _is_ a process of grinding though (except when a
traditional steel is used).


Another point. You usually hone the front face with a few strokes, then
the rear face with a few and then back the front again. Not quite sure
why but this is general 'good advice' given in the trade. Ratio of two
to one, front to back.

Do you mean 2:1 front to back, or 2 then 2? If the former, how do you
define front and back then? (most kitchen knives are symmetrical).


Good start though and an excellent idea. I don't know how most people
can use the rubbish knives they have, and don't sharpen properly.

Even a below par sharpen is far better than a totally blunt knife, as
is so often found in the home kitchen.


NT

wrote:
Another one to play with....


NT


Sharpen cutlery

version 2...


Sharpen cutlery


Sharp kitchen knives make hard jobs easy, reduce fatigue, and reduce
the risk of accident due to putting too much force on a knife and
losing control.


=Considerations=
==Metals==
The quality of steel used in knives varies fairly widely. Some knives
can take a very sharp edge, most can be made fairly sharp, and the
occasional bad one is barely capable of becoming sharp at all.


==Angles==
Specific angles are best for specific metals and jobs, but with
kitchen knives one is usually working with unknown budget metal, and
not looking for a razor edge. The thinner the angle, the more sharp
the blade is initially, but the quicker it blunts. And with popular
low cost cutlery, blunting at narrow angles can be very quick. Also
the poorest quality metal, found on some table knives, is sometimes
unable to take 35 degrees without the cutting edge pitting during
grinding.

The following angles work well for me:

Cutting knives: 30 degrees.
* sharp
* blunts quickly if used with glass boards or ceramic plates

Table knives: 40 degrees
* mildly sharp
* child friendly
* works on any steel
* retains its mildly sharp edge well
* Not very sharp, but a big improvement on a blunt knife.

Special sharp: 20-25 degree
* extra sharp
* a knife ground like this is occasionally useful in the kitchen
* needs to be handled with care
* not child safe
* always cut onto a soft surface, or the edge is lost quickly


Its possible to place a printed angle under the grinder to act as a
guide if wanted. Personally I don't lose sleep over precision here,
the average kitchen knife is far from a critical high performance
tool. If you buy high quality knives though, you should follow the
original grinding angles to ensure you get the best possible
performance. Most people however are working with unknown material,
and its not possible to specify what angle will give the best
performance for each knife.

If you're determined to tweak your grinding angles to get peak
performance out of each knife, it may be worth noting that in my
experience the worst quality metal is found not on cheapo knives, but
on pretty table knives from a popular major manufacturer that most
buyers regard as quality.

If you're having difficulty maintaining the right angles, one can buy
angle guides that will hold the blade correctly aligned.


=Serrated blades=
Serration is a way to get much of the effect of sharpness without real
sharpness being present. Serration is widely disliked among knife
sharpeners, but its an easy way to get cutting ability from cheap
metal, its liked by many end users, and it has its uses, such as
cutting frozen food. Consequently it may be wished to sharpen serrated
knives without loss of serration.

There's no easy way to maintain the serrated shape indefinitely while
sharpening using home equipment. There are however a few successful
ways to sharpen serrated knives.


==Sharpen the back==
Often knives are serrated asymmetrically, with serrations ground on
one side only. In this case the flat other side of the blade can be
ground. Only a small amount of grinding is needed. A final single very
light pass on the serrated side removes any burr.


==Sharpen the tips==
Where the above method doesn't produce enough sharpening, the knife
may be ground on the serrated side(s) too. The idea here is not to
thoroughly grind all areas of the blade, but rather to make the usual
fairly quick pass over the blade. This will sharpen the tips only,
giving a big improvement in performance. Its good enough for most
uses.


==Rough edge==
This technique produces a rough edge with mini serrations, and works
well with an angle grinder. I don't know if its possible to do this
approach with other grinding tools. The blade is sharpened as normal,
but its moved over the grinder disc as quickly as can be done safely,
rather than gradually. The idea is to pass the whole length of the
blade over the disc in about half a second. The result is fairly
sharp, but rough and uneven. It effectively creates ungraceful
serrations. A rough old grinding disc creates more serration than a
new smooth one.

This method isn't often the best choice, but can be used where
existing serrations are too uneven to sharpen usefully, and where
conversion to a plain edge is unworkable for some reason, eg not
enough metal left, or would require grinding an excessive amount of
metal away. Its also a very quick way to deal with serrated knifes
that are barely worth the trouble of sharpening.


==Sharpen all==
In principle its possible to sharpen cresent shaped serrations and
maintain their shape. However its very time consuming and not very
pointful, so not normally done.


==Plain blade conversion==
The final option is to remove enough metal to convert the knife to a
plain blade. This is usually not necessary, but is the only way to
ensure a blade that's sharp every millimetre of its length.


=One sided blades=
Many knives come ground on one side only. This causes them to wander
off line when cutting, which is a pain in the kitchen. Its a good idea
to grind them on the unground side to reduce this tendency, only
making a final burr removing pass on the originally ground side.


=Ceramic knives=
?

=Pre-stainess knives=
Knives that were made before stainless steel became popular are
occasionally seen. Non-rusting cutlery contains a mix of steel,
copper, and probably other things, and the metal is usually blotchy
and darkened from food stains. These are seen in collections of pre-
war cutlery.

I know nothing about their sharpening characteristics though. Until
someone that does know can tell us, I would expect the mixed metal
content would make them soft, and best suited to 40 degree sharpening.


=Sharpening tools=
There are a few ways to sharpen kitchen blades.

==Manual==
Manual sharpening is slow, and stock removal even slower. Nevertheless
some people prefer this approach.

===Stones===
Oilstones are abrasive stones that work well with oil.

Wetstones are abrasive stones that work best wetted with water.

Diamond sharpening stones are flat plates coated with diamond dust.
Diamond will grind even the hardest materials, such as ceramic knives.


===Steel===
A traditional steel doesn't grind. Rather it restores a
microscopically bent cutting edge by restraightening it. These were
traditionally used between sharpenings as an intermediate way to
prolong sharpness.

Modern performance knives don't use steel that suffers this fate, so a
steel isn't much use with them. However cheaper knives do use softer
metal, and can benefit from use of a steel.

===Abrasive Steel===
The abrasive steel is a traditional steel but with some added
abrasive. It primarily acts like a traditional steel, but also
provides a little grinding as well, thus prolonging sharpening
intervals further. However hand powered grinding of any sort is a
labour intensive way to sharpen knives compared to machine grinding.


===Sandpaper===
Abrasive paper may be used on a dead flat surface (eg glass) for
sharpening. This has popularly become known as the 'scary sharp'
method, as by progressing through increasingly fine grades its
possible to achieve a very high level of sharpness.

Several different abrasives are found on abrasive paper, including
alox, emery, carbide, zirconium, sharp sand and others. These are
frequently loosely referred to as sandpaper. To sharpen steel blades,
a sufficiently hard abrasive is required, such as emery, carbide or
zirconium.


===Chainsaw file===
The small size makes it slow.


==Motorised==
Powered knife sharpening is quicker.
===Kitchen knife sharpener===
Many low cost motorised domestic knife sharpeners are available. One
go with one of these caused me to abandon all hope.

There are also good quality machines that can produce a fine edge.
Many users like them, but they tend to be pricey.


===Bench grinder===
Bench grinders are the best option in most respects. They are the
standard engineer's choice for sharpening a wide range of blades. They
don't look particularly graceful in the kitchen though. They also lack
the speed of an angle grinder.


===Angle grinder===
The suggestion of using an [[angle grinder]] to sharpen knives often
raises eyebrows. However they are very fast and effective, able to
sharpen a totally blunt knife in 20-30 seconds, and remove stock to
create a new edge in under a minute. This speed makes it easy and
practical to sharpen all one's knives quickly, table knives included.
For busy people this is a real advantage.

====Flaws====
As sharpeners, angle grinders have some sizeable flaws, and some
precautions are very necessary.

The knife blade must be kept moving, don't ever grind one stationary
spot. Doing so would overheat the metal in 5-10 seconds, and if this
happens the blade will never be able to keep an edge again.

The very high disc speed can throw a knife if held to the disc in the
wrong direction. Always confirm the direction of rotation before use
(eg with a match etc), and be sure to always hold the knife the right
way.

Always use indirect vent goggles, ear defenders, and ideally a full
face mask too.

Never use a damp grit disc in an angle grinder, and don't dip cutlery
in water to cool it when using such a disc. Damp grit discs can fail
violently.

Keep your face out of the plane of rotation of the disc. Grit discs
can break violently.

Angle grinder grit discs are somewhat coarse. This coarseness limits
the level of sharpness available, but the result is plenty sharp
enough for normal kitchen use. It would not satisfy most die hard
knife sharpeners though. Use only the very lightest pressure to
achieve the sharpest edge.

Don't use these tools if tired, drunk, drugged, or not really with it.
They aren't a nice friendly power tool.


====Use====
If you have an angle grinder stand, use it. If not, the tool may be
held on its back to minimise fatigue. Sitting down with it on your
knees (in your hand of course) makes it easy to pass knives both ways.
However you position it, keep a good firm grip at all times.

To sharpen, move the blade as shown past the disc. Use the lightest of
pressure only. 2 strokes on each side of the blade is enough for any
blade that already has an edge formed, ie doesn't need stock removal.
Finally make a burr removing pass along the other side of the blade
(compared to the previous stroke). Use all the pressure of a feather,
so the blade only just barely touches the disc.

Stock removal requires just a little pressure, and more passes. Never
get the metal hot though, if in any doubt just put the knife down and
come back to it a bit later. Dipping the knife in water is not
recommended with grit discs, damp can cause violent disc failure.


===Die grinder===
Carbide stones (grey) are qiucker than alox (asstd light colours),
especially for stock removal.


===Powerfile===
I sharpen most things with a B&D powerfile and it's very effective.
If you've not come across this tool before it's like a belt sander but
the belts are only 12mm (IIRC) wide. It allows me more control than
my angle grinder and is a *lot* safer as the belt is significantly
slower and the energy much less. It can be used one-handed quite
safely so I usually just hold the knife against a stop with the blade
protruding over the edge of the workbench and run the powerfile over
it judging the angle by eye. Simple, safe and effective.


=After grinding=
Knives should be washed after grinding. Grind stones can harbour all
sorts of detritus, oil residues, decayed food & so on.

Its also worth warning the rest of the household if previously blunt
knives are now psychopathically sharp.


=Care of sharp knives=
Use of 30 degree knives on glass chopping boards or ceramic plates
blunts them quickly. Most knife sharpeners prefer wooden chopping
boards.

Knives with relatively soft steel benefit from use of a steel between
sharpenings.


==See Also==
* [[Knives]]
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]



[[Category:Tools]]

wrote:


sharpening _is_ a process of grinding though (except when a
traditional steel is used).

Agreed. I was trying to differentiate from re-grinding a blade that has
become too thick to sharpen.

Do you mean 2:1 front to back, or 2 then 2? If the former, how do you
define front and back then? (most kitchen knives are symmetrical).


Yes, sorry. Ambiguous. Front face is what faces you with the sharp edge
at the bottom and the point pointing to the left. I was pleased to get
the explanation of why. Number of sharpening strokes depends on tools
you use and the hardness and bluntness of the blade. Say you use three.
It's three front, three back, three front.


Good start though and an excellent idea. I don't know how most people
can use the rubbish knives they have, and don't sharpen properly.

Even a below par sharpen is far better than a totally blunt knife, as
is so often found in the home kitchen.

Hmmm. Not sure about that. Horrible tea better than no tea? Why not
learn how to do it? I think that's your motivation in writing this wiki
isn't it? I hate cooking in other people's kitchens due to the knives
and lack of a decent board. Now I take my own. Deffo nothing but plastic
or wood for the board.



I think the spelling is whetstone. It can be dry or wet but is used to
whet, or sharpen.

Am I being pedantic?? Don't think so.

Peter Scott

PeterC wrote:
On Wed, 15 Apr 2009 13:01:24 +0100, Peter Scott wrote:

Another point. You usually hone the front face with a few strokes, then
the rear face with a few and then back the front again. Not quite sure
why but this is general 'good advice' given in the trade. Ratio of two
to one, front to back.

I think it's so that there isn't a minute burr turned over to one side -
ISTR looking at a knife after sharpening 1 side and, under a low-powered
microscope, there was a bit to 1 side.
Thanks. I thought it might be something like that. A bit like the stroke
on the flat side of a woodcutting chisel.

Peter Scott

On Wed, 15 Apr 2009 14:27:48 +0100, Peter Scott wrote:

PeterC wrote:
On Wed, 15 Apr 2009 13:01:24 +0100, Peter Scott wrote:

Another point. You usually hone the front face with a few strokes, then
the rear face with a few and then back the front again. Not quite sure
why but this is general 'good advice' given in the trade. Ratio of two
to one, front to back.

I think it's so that there isn't a minute burr turned over to one side -
ISTR looking at a knife after sharpening 1 side and, under a low-powered
microscope, there was a bit to 1 side.
Thanks. I thought it might be something like that. A bit like the stroke
on the flat side of a woodcutting chisel.

Peter Scott

Yes, I sharpened some chisels (cheap set, so blunt from new) and they're
quite difficult due to needing no taper on 1 side, so making sure that
there isn't a burr takes some time.
--
Peter.
You don't understand Newton's Third Law of Motion?
It's not rocket science, you know.

On 15 Apr, 02:03, wrote:
Another one to play with....

===Steel===
A traditional steel doesn't grind. Rather it restores a
microscopically bent cutting edge by restraightening it. These were
used between sharpenings as an intermediate way to prolong sharpness.

Modern performance knives don't use steel that suffers this fate, so a
steel isn't much use with them. However cheaper knives do use softer
metal, and may benefit from use of a steel.


You have obviously never seen a steel.
I have two carving sets, each comprising a steel, a knife and a fork.
The older knife (circa 90 years) has worn down to around 6 inches
long, and around 1]4 inch deep, from
its original length of 10 inches. It has only been dressed on the
steel.
When the newer knife (circa 40 years) is sharpened with the steel,
minute shavings
can, in the right light, be seen falling from the blade.
Both steels, when viewed closely, have longitudinally grooves which
act as
a file. I have never seen a steel without these grooves, and I have
seen
a hell of a lot of steels.

wrote in message
...
Another one to play with....


NT


Sharpen cutlery


[...]

==Serrated blades==
Serration is a way to get much of the effect of sharpness without real
sharpness being present. Serration is widely disliked among knife
sharpeners, but its an easy way to get cutting ability from cheap
metal, its liked by many end users, and it has its uses, such as
cutting frozen food. Consequently it may be wished to sharpen serrated
knives without loss of serration.

There's no easy way to maintain the serrated shape indefinitely while
sharpening using home equipment. There are however a few successful
ways to sharpen serrated knives.

[...]

Serrated bread knifes, best thing since sliced bread. Haven't actually used
mine on bread but the thing's bloody marvellous for topping off Shreddies
cartons and dismembering carboard packages from Ebay.
I sharpen it with a cheap sharpener from Lidl. Looks like a plastic sword
handle, except it has fitted a little "V" shaped piece of Tungsten Carbide.
Just pull a knife through it once or twice. Serrations no problem. A bread
knife then segues into a weapon of mass destruction. (Makes me whince just
to think how sharp the edge is .

On Wed, 15 Apr 2009 20:26:50 UTC, "john jardine"
wrote:

Serrated bread knifes, best thing since sliced bread. Haven't actually used
mine on bread but the thing's bloody marvellous for topping off Shreddies
cartons and dismembering carboard packages from Ebay.

Good for cutting foam for lining equipment boxes too!

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

mr fuxit wrote:
On 15 Apr, 02:03, wrote:
Another one to play with....

===Steel===
A traditional steel doesn't grind. Rather it restores a
microscopically bent cutting edge by restraightening it. These were
used between sharpenings as an intermediate way to prolong sharpness.

Modern performance knives don't use steel that suffers this fate, so a
steel isn't much use with them. However cheaper knives do use softer
metal, and may benefit from use of a steel.


You have obviously never seen a steel.

why is it when people say 'you have obviously never' theyre so often
wrong?

The filing effect is news to me, but I'll include it.


NT

I have two carving sets, each comprising a steel, a knife and a fork.
The older knife (circa 90 years) has worn down to around 6 inches
long, and around 1]4 inch deep, from
its original length of 10 inches. It has only been dressed on the
steel.
When the newer knife (circa 40 years) is sharpened with the steel,
minute shavings
can, in the right light, be seen falling from the blade.
Both steels, when viewed closely, have longitudinally grooves which
act as
a file. I have never seen a steel without these grooves, and I have
seen
a hell of a lot of steels.

I think it is worth mentioning that to get an angle of (eg.) 30
degrees with a stone, you sharpen each side of the knife at an angle
of 15 degrees! Took me longer than I'd care to admit to realise
that...

J^n

jkn wrote:
I think it is worth mentioning that to get an angle of (eg.) 30
degrees with a stone, you sharpen each side of the knife at an angle
of 15 degrees! Took me longer than I'd care to admit to realise
that...

J^n

Very good point. I have never measured the angle I use when sharpening
on a flat diamond surface. It is very shallow and presumably 15 degrees.

Peter Scott

In message
, jkn
writes
I think it is worth mentioning that to get an angle of (eg.) 30
degrees with a stone, you sharpen each side of the knife at an angle
of 15 degrees! Took me longer than I'd care to admit to realise
that...

It's also worth mentioning that if the blade has a titanium nitride edge
coating you should only sharpen it on the uncoated side.



--
Bernard Peek

wrote:
Another one to play with....


NT


Sharpen cutlery

How about scissors?


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On 15 Apr, 21:26, "john jardine" wrote:
wrote in message

...



Another one to play with....

NT

Sharpen cutlery

[...]

==Serrated blades==
Serration is a way to get much of the effect of sharpness without real
sharpness being present. Serration is widely disliked among knife
sharpeners, but its an easy way to get cutting ability from cheap
metal, its liked by many end users, and it has its uses, such as
cutting frozen food. Consequently it may be wished to sharpen serrated
knives without loss of serration.

There's no easy way to maintain the serrated shape indefinitely while
sharpening using home equipment. There are however a few successful
ways to sharpen serrated knives.

[...]

Serrated bread knifes, best thing since sliced bread. *Haven't actually used
mine on bread but the thing's bloody marvellous for topping off Shreddies
cartons and dismembering carboard packages from Ebay.
I sharpen it with a cheap sharpener from Lidl. Looks like a plastic sword
handle, except it has fitted a little "V" shaped piece of Tungsten Carbide.
Just pull a knife through it once or twice. Serrations no problem. A bread
knife then segues into a weapon of mass destruction. (Makes me whince just
to think how sharp the edge is .

I think the distinction between scalloped-edge knives and serrated-
edge knives needs to be made clear. Scalloped knives can be re-
sharpened on a steel, serrated usually can't without specialised
machinery (or if you are 'lucky' enough to have a serrated knife that
has a flat face.

I find serrated knives rip their way through things, and clog up with
shredded meat, and if used as a bread knife, generate vast quantities
of crumbs. My bread knives are scalloped.

Serrated: /\/\/\/\/\/\/\/\/\ - lots of little pointy teeth, like a
saw

Scalloped _--'--_--'--_--'--_ - smoothly curved wave-like edge

I _hate_ using serrated edge knives - tacky, cheap, shoddy, goods. I
agree that cutting boards should only be either wood or (softish)
plastic - never, ever glass or stone, and don't use a stainless steel
counter-top as a cutting board either.

I get the best edge on carbon steel blades using a whetstone,
lubricated with oil - for food use, I use olive oil, 'cos it is what I
have to hand. When sharp, I can easily shave the hair off the back of
my hand with the blade.

Sid

wrote:
Another one to play with....


NT

OK, I've now incorporated a whole bunch of people's suggestion, plus
more material too. Any more suggestions, keep em coming...


NT


Sharp kitchen knives make hard jobs easy, reduce fatigue, and reduce
the risk of accident due to putting too much force on a knife and
losing control.


=Metals=
==Stainless steel==
The quality of steel used in knives varies fairly widely. Some knives
can take a very sharp edge, most can be made fairly sharp, and the
occasional bad one is barely capable of becoming sharp at all.

==Ceramic knives==

==Pre-stainess knives==
Knives that were made before stainless steel became popular are
occasionally seen. Non-rusting cutlery contains a mix of steel,
copper, and probably other things, and the metal is usually blotchy
and darkened from food stains. These are seen in collections of pre-
war cutlery, some of which is still in domestic use.

I know nothing about their sharpening characteristics though. Until
someone that does know can tell us, I would expect the mixed metal
content would make them much softer than stainless steel, and best
suited to a much wider sharpening angle. Bear in mind its not
essential to have a thin cutting angle (even an 80 degree blade can
cut vegetables).

==Titanium==
Titanium knives are steel with a hard titanium nitride coating. These
should only be ground on the uncoated side.


=Angles=
Specific angles are best for specific metals and jobs, but with
kitchen knives one is usually working with unknown budget metal, and
not looking for a razor edge. The thinner the angle, the more sharp
the blade is initially, but the quicker it blunts. And with popular
low cost cutlery, blunting at narrow angles can happen very quickly.

The poorest quality metal, found on some table knives, is sometimes
only able to take a very wide angled edge without the cutting edge
pitting during grinding.

Its possible to place a printed angle under the grinder to act as a
guide if wanted. Personally I don't lose sleep over precision here,
the average kitchen knife is far from a critical high performance
tool. If you buy high quality knives though, you should follow the
original grinding angles to ensure you get the best possible
performance. Most people however are working with unknown material,
and its not possible to specify what angle will give the best
performance for each knife.

If you're determined to tweak your grinding angles to get peak
performance out of each knife, it may be worth noting that in my
experience the worst quality metal is found not on cheap knives, but
on pretty table knives from a popular major manufacturer that most
buyers regard as quality.

If you're having difficulty maintaining the right angles, one can buy
angle guides that will hold the blade correctly aligned. Its also
possible to cut a piece of wood to rest the knife on when grinding.

A lot of table knives have no ground edge at all, and this makes them
a pain to use at the table. I like to grind a very wide angled edge
onto them. While not especially sharp, it makes them perform
comfortably at the table, and the mild level of sharpness is safe for
children.

30 degree sharpening means grinding an angle of 15 degrees to the
blade on each side, not 30 degrees each side.

Beginners should note that the angle between grinder and blade needs
to be consistently controlled, and must match the existing ground
angle on the knife, otherwise:
* if the angle is too narrow, the grinder won't touch the sharp edge
at all
* if the angle is too wide, the blade will be made blunter

Some people prefer to use glass chopping boards, often on hygiene
grounds. Glass blunts sharp blades very quickly, and such people are
best to use the widest angle that gives sufficient sharpness, in order
to improve the blade's life on such a hard surface.


=Order of grinding=
When a knife is ground, the stone applies sideways force to the blade,
and this causes the very thinnest edge to bend over. This bent over
edge is called a burr. A burr is easy to feel: if you run a finger
across the blade (NOT along it), the blade grabs in one direction, but
slides easily the other way. A burr prevents sharpness, and part of
the grinding process is to either bend the burr back straight or grind
it away. To achieve this, grinding is normally alternated between
sides.
* With powered grinders the knife is best run over the stone once
before changing sides, so the order of sharpening would be L,R,L,R,
etc
* With hand held grinders, 2 or 3 strokes each side is easier and thus
quicker, so the order of sharpening would be L,L,R,R,L,L,R,R, etc

Some types of blade are best sharpened on only one side. However this
forms a burr, and for a good result this should be removed at times
with a stroke on the other side. Where its strongly desirable not to
grind one other side, such as with titanium blades, the coated side
can have the burr straightened with a steel instead of a grindstone.


=Sharpening and reforming=
The majority of grinding will consist of just resharpening an existing
ground edge. This needs relatively little grinding to achieve.

If a knife doesn't have a ground edge on it, as is often the way with
table knives, or the edge is very damaged, it will be necessary to
grind it down much more to form a new well shaped edge. This of course
takes a lot more grinding than just a sharpen, and a motorised grinder
is a big time saver here.


=Blade thinning=
Its usual to thin the blade near the cutting edge for best cutting
performance. On the average knife, there are 2 ground angles. First
there is a large expanse of narrow angle grinding to thin the metal,
then a far smaller grind along the edge to make it sharp.
* If a cutting knife wears so far that the edge becomes thick again,
bulk grinding is needed to rethin the edge
* table knives may be ground without thinning, since only a low level
of sharpeness is wanted.


=Serrated blades=
Serration is a way to get much of the effect of sharpness without real
sharpness being present. Serration is widely disliked among knife
sharpeners, but its an easy way to get cutting ability from cheap
metal, its liked by many end users, and it has its uses, such as
cutting frozen food. Consequently it may be wished to sharpen serrated
knives without loss of serration.

There's no easy way to maintain the serrated shape indefinitely while
sharpening using home equipment. There are however a few successful
ways to sharpen serrated knives.


==Sharpen the back==
Often knives have serrations ground on one side only. In this case the
flat other side of the blade can be ground. Only a small amount of
grinding is needed. Finally just a little very light grinding is done
on the serrated side solely to remove the burr.


==Sharpen the tips==
Where the above method doesn't produce enough sharpening, the knife
may be ground on the serrated side(s) too. The idea here is not to
thoroughly grind all areas of the blade, but rather to make the usual
fairly quick pass over the blade. This will sharpen the tips only,
giving a big improvement in performance. Its good enough for most
uses.


==Rough edge==
This technique produces a rough edge with mini serrations, and works
well with an angle grinder. I don't know if its possible to do this
approach with other grinding tools. The blade is sharpened as normal,
but its moved over the grinder disc as quickly as can be done safely,
rather than gradually. The idea is to pass the whole length of the
blade over the disc in about half a second. The result is fairly
sharp, but rough and uneven. It effectively creates ungraceful
serrations. A rough old grinding disc creates more serration than a
new smooth one.

This method isn't often the best choice, but can be used where
existing serrations are too uneven to sharpen usefully, and where
conversion to a plain edge is unworkable for some reason, eg not
enough metal left, or would require grinding an excessive amount of
metal away. Its also a very quick way to deal with serrated knifes
that are barely worth the trouble of sharpening.


==Sharpen all==
In principle its possible to sharpen cresent shaped serrations and
maintain their shape. However its very time consuming and not very
pointful, so not normally done.


==Plain blade conversion==
The final option is to remove enough metal to convert the knife to a
plain blade. This is usually not necessary, but is the only way to
ensure a blade that's sharp every millimetre of its length.


=One sided blades=
Many knives come ground on one side only. This causes them to wander
off line when cutting, which is a pain in the kitchen. Its a good idea
to grind them on the unground side to reduce this tendency, only
making the very minimum grinding on the originally ground side to
remove the burr.


=Sharpening tools=
There are a few ways to sharpen kitchen blades.

==Manual==
Manual sharpening is slow, and stock removal even slower. Nevertheless
some people prefer this approach.

===Stones===
* Oilstones are abrasive stones that work well with oil.
* Waterstones are abrasive stones that work best wetted with water.
* Both are called whetstones

===Diamond===
Diamond sharpening stones are flat plates coated with synthetic
diamond dust. Diamond will grind even the hardest materials, such as
ceramic knives.


===Steel===
A traditional steel restores a microscopically bent cutting edge by
restraightening it. It also acts as a file. These were traditionally
used between abrasive sharpenings as an intermediate way to prolong
sharpness.

Most knives use metal soft enough to benefit from use of a steel.


===Abrasive Steel===
The abrasive steel is a traditional steel but with some added
abrasive. It primarily acts like a traditional steel, but also
provides a little grinding as well, thus prolonging sharpening
intervals further.


===Sandpaper===
Abrasive paper may be used on a dead flat surface (eg glass) for
sharpening. This has popularly become known as the 'scary sharp'
method, as by progressing through increasingly fine grades its
possible to achieve a very high level of sharpness.

Several different abrasives are found on abrasive paper, including
alox, emery, tungsten carbide, zirconium, sharp sand and others. These
are frequently loosely referred to as sandpaper. To sharpen steel
blades, a sufficiently hard abrasive is required, sand is not
suitable.


===Chainsaw file===
The small size makes it slow.


===Steel wheels===
The knife blade is drawn over a set of hard steel discs. These deburr
and to some extent file the knife. Usually the angle is not
adjustable. If you're happy with the fixed angle, these work like a
steel, but are easier to use as the angles are controlled by the
sharpener.


===V shaped stone===
A small V shaped stone in a handle makes control of angles easier.
However they're not adjustable. Easy to use if you're happy with the
same preset angle on everything. These are one of the few tools that
can sharpen some types of serration effectively.


==Motorised==

===Kitchen knife sharpener===
Low cost motorised domestic knife sharpeners are available. One go
with one of these caused me to abandon all hope.

There are also good quality machines that can produce a fine edge.
Many users like them, but they tend to be pricey.


===Bench grinder===
Bench grinders are probaby the best option for all-purpose sharpening.
They are the standard engineer's choice for sharpening a wide range of
blades. They don't look particularly graceful in the kitchen though.
They also lack the speed of an angle grinder.


===Angle grinder===
The suggestion of using an [[angle grinder]] to sharpen knives often
raises eyebrows. They are very fast and effective, able to sharpen a
totally blunt knife in 20-30 seconds, and remove stock to create a new
edge in under a minute. This speed makes it easy and practical to
sharpen all one's knives quickly, table knives included. For busy
people this is a real advantage.

However, as sharpeners they have some sizeable flaws, and some
precautions are very necessary.

====Flaws====
The knife blade must be kept moving, don't ever grind one stationary
spot. Doing so would overheat the metal in 5-10 seconds, and if this
happens the blade will never be able to keep an edge again.

The very high disc speed can throw a knife if held to the disc in the
wrong direction. Always confirm the direction of rotation before use
(eg with a match etc), and be sure to always hold the knife the right
way. Position everything so that if a knife is ever thrown, it will
fly away from you.

Always use indirect vent goggles, ear defenders, and ideally a full
face mask too.

Never use a damp grit disc in an angle grinder, and don't dip cutlery
in water to cool it when using such a disc. Damp grit discs can fail
violently.

Keep your face out of the plane of rotation of the disc. Grit discs
can break violently.

Angle grinder grit discs are somewhat coarse. This coarseness limits
the level of sharpness available, but the result is plenty sharp
enough for normal kitchen use. It would not satisfy most die hard
knife sharpeners though. Use only the very lightest pressure to
achieve the sharpest edge.

Don't use these tools if tired, drunk, drugged, or not really with it.
They aren't a nice friendly power tool.


====Use====
If you have an angle grinder stand, use it. If not, the tool may be
held on its back to minimise fatigue. Sitting down with it on your
knees (in your hand of course) makes it easy to pass knives both ways.
However you position it, keep a good firm grip at all times.

To sharpen, move the blade as shown past the disc. Use the lightest of
pressure only. 2 strokes on each side of the blade is enough for any
blade that already has an edge formed, ie doesn't need stock removal.
Finally make a burr removing pass along the other side of the blade
(compared to the previous stroke). Use all the pressure of a feather,
so the blade only just touches the disc.

Stock removal requires just a little pressure, and more passes. Never
get the metal hot though, if in any doubt just put the knife down and
come back to it a bit later. Dipping the knife in water is not
recommended with grit discs, damp can cause violent disc failure.


===Die grinder===
Carbide stones (grey) are quicker than alox (asstd light colours),
especially for stock removal.


===Powerfile===
I sharpen most things with a B&D powerfile and it's very effective.
If you've not come across this tool before it's like a belt sander but
the belts are only 12mm (IIRC) wide. It allows me more control than
my angle grinder and is a *lot* safer as the belt is significantly
slower and the energy much less. It can be used one-handed quite
safely so I usually just hold the knife against a stop with the blade
protruding over the edge of the workbench and run the powerfile over
it judging the angle by eye. Simple, safe and effective.


=After grinding=
Knives should be washed after grinding. Grind stones can harbour all
sorts of detritus, oil residues, decayed food & so on.

Its also worth warning the rest of the household if previously blunt
knives are now psychopathically sharp.


=Care of sharp knives=
Use of sharp knives on glass chopping boards or ceramic plates blunts
them quickly. Most knife sharpeners prefer wooden chopping boards.

Knives with relatively soft steel benefit from use of a steel between
sharpenings.


==See Also==
* [[Knives]]
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]



[[Category:Tools]]
[[Category:Kitchens]]
[[Category:Metal]]