Electric knife sharpeners..... Answered
Back in the day we already had these tiny grinding wheel like tools in the kitchen.
Plug it in, press a button and slide the knife through.
The blade was supposed to come out razor sharp if you trusted the ads....
For obvious reasons a grinding wheel moving along the edge is not a good thing, especially not if both te up and the down movement work on the edge.
As soon as they appeared they disappeared only to emerge years later in a "modern" form.
The latest incarnation now comes with ceramic wheels to give an even sharper finnish LOL
The problem however is still the same, first the action of the whells then the fact that it is next to impossible to get different angles.
They are really only good for some knifes you use in the shed if nothing else is available.
A now much hyped electric sharpener is basically just a tiny belt sander with guides attached to it.
And don't get me wrong, they come in handy for certain works.
But if you ever used a belt sander on a flat piece of steel you realise that it is quite impossible to get a flat surface finnish.
The belt curves around the edge and this results in a curved or beveled edge.
Obviously the claim to sell these is that a beveled edge has superior strength and sharpness compared to a straight angled edge.
And then there is the ability to adjust not just the sharpening angle but als the grid of the sandpaper.
The finer you go, the better the result and sharpness...
Now if we trust those who create swords from raw iron ore then something is wrong with the belt approch.
These guys would tell you that you should always use a flat stone and to slice a piece of the stone.
But also that a beveled edge is a sign of wear, something a good butcher will confirm.
The angle of the edge party affects how sharp and durable the edge will be.
Usually there is a compromise between blade thickness, meterial and edge angle.
Just go from razor blade to an axe and include severel types of knifes between them.
So a beveled edge in my opinion is only good for brute force tools but not that good for fine slicing and dicing.
I tried to sharpen a wood chisel on one of the belt sander toys...
It turned out to be far less precise and the edge was not fully straight.
Could be down to lack of experience but if you ever try it let me know your results.
The produced edge was also quite unusal and often bad when used as intendet.
Far more chipping than cutting.
Difference between straight angle and beveled angle when using a knife.
You might want to do some lonely woodworks while fishing.
A good knife now just eats into the wood and lets you cut and slice pieces of at almost any angle of the blade.
With a beveled edge however you face the problem that your working angle is drastically reduced.
Tilt the knife a bit too much and you suddenly just slide off the wood and into your flesh.
If you grind and hone a knife to a 20° angle on a flat stone than from all angles above 20° you can cut.
If you belt sand a knife to a 20° angle you end up with a bow over this angle.
The actual usable working angle can be as low as 40° on a thicker blade.
In theory it is possible to overcome this bevel problem.
Sanders with a backing plate for example or by using just enough pressure to take material off.
The first will destroy your belts quickly, the second takes forever.
Some people just sand the knife at an angle to the belt, so instead of having the belt running at 90° to the edge it runs at 60 or 40°.
Reduces the buckle but also the sharpness as the actual edge is now rounded.
The only real way to sharpen a knife would be with a cutting or slicing motion, something that usually cuts your belts once the edge becomes sharp enough.
So should you use them after all?
As with all tools it comes down to quality and how you use the tool.
If you know what you do and what the limitations are an electric sharpener can save you a lot of time.
Someone with a desire for razor sharp knifes and tools might only use them on the lawn mower...
You can however very well use sandpaper for sharpening a knife, which I will explain in another post....