Sharpening systems which keep a constant grinding angle

T

Titanium

Joined
Nov 23, 2003
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I'm using a guided angle sharpening systems with swivel arms.

One problem with guided grinding systems like Edge Pro, TSPROF, KME and Wicked Edge is that the grinding angle changes if there is a curve (to the tip) in blade.
Here someone made a very detailed analysis of the change in the grinding angle:
https://docs.google.com/file/d/0B8r...SlU/edit?resourcekey=0-DKAA4nQf5phamoMlG7cW9A

A solution to the problem that the grinding angle changes towards the tip if there is a curve in the blade, are guided angle sharpening systems with swivel arms:

Here are videos of someone using such a system:




The secret of those systems is a pivoting axis (red) which stands perpendicular (90Ā° angle) (green) on the plane of the blade (blue).




It doesn't matter how you turn the knife, the grinding angle to the stone keeps the same.

I wonder why those systems are not popular in the US?
 
There are plenty of problems with the systems you show. It really comes down to what set of compromises you want to have. Those rods that hold the knives are all poorly supported so you will get inconsistent angles when used. There are a bunch of better sharpener ideas coming out of Russia, but again they all suffer from poor execution too. I prefer to have my angles more repeatable but have the angle change as the stone follows the knife tip. I minimize the compromise with the knives I buy, I only buy knives I want to sharpen, which means no swoopy tips and NO RECURVES!

While showing off knife sharpener designs here is one of my favorites, but again I find the execution of both the design and build lacking. Back to that compromise thing, this design is hard to do right.


After looking at it more it is an interesting concept. I like the angle adjuster in your first video, it looks like a big improvement over the earlier version. But using threaded bolts as pivots is a bad/hack shortcut.
 
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I'm not sure about other knife sharpening systems, but when using the Wicked Edge, you move the blade forward or back in the vise until the stones track properly along the edge bevels.
 
000Robert said:
I'm not sure about other knife sharpening systems, but when using the Wicked Edge, you move the blade forward or back in the vise until the stones track properly along the edge bevels.
Click to expand...
Not to mention, unless you're extremely OCD, it doesn't really matter in the grand scheme of things. I just write down the position I clamp my knives at and the angles. Then I just sharpen without giving it another thought.
 
tokerblue said:
Not to mention, unless you're extremely OCD, it doesn't really matter in the grand scheme of things. I just write down the position I clamp my knives at and the angles. Then I just sharpen without giving it another thought.
Click to expand...

Some people like their edge bevels to look the same from the heel to the tip. If the blade isn't positioned correctly in the WE vise, the edge bevels can look skinnier or thicker on the curve of the belly going to the tip. You just use a sharpie on the edge bevels and adjust the blade till the stones hit the center of the edge bevels from the heel to the tip. Then record the position of the blade for future sharpening's.
 
000Robert said:
I'm not sure about other knife sharpening systems, but when using the Wicked Edge, you move the blade forward or back in the vise until the stones track properly along the edge bevels.
Click to expand...
That is correct, I forgot to mention it.
The problem only applies when using the Edge Pro not correctly (not moving the blade) or with systems similar to the Edge Pro, but with the blade position fixed by a clamp.
 
Diemaker said:
... Those rods that hold the knives are all poorly supported so you will get inconsistent angles when used. ...
Click to expand...
That is no problem at all, the rod are stiff enough to guide the blade with a constant angle.
Diemaker said:
... But using threaded bolts as pivots is a bad/hack shortcut. ...
Click to expand...
Because there is no play, when fixed with the two brass nuts it is no problem.
I was not able to feel play in the joints with the threaded bolts.
 
000Robert said:
Some people like their edge bevels to look the same from the heel to the tip. If the blade isn't positioned correctly in the WE vise, the edge bevels can look skinnier or thicker on the curve of the belly going to the tip. You just use a sharpie on the edge bevels and adjust the blade till the stones hit the center of the edge bevels from the heel to the tip. Then record the position of the blade for future sharpening's.
Click to expand...
Also, it's not just a factor of the stone angle. Most knives don't maintain the same thickness behind the edge from the heel to the tip of the blade. If the stock is thicker towards the tip (it usually is) and you maintain a consistent angle, the bevel will be wider towards the tip. You actually have to maintain an INconsistent angle to keep a consistent bevel width, which is going to be a tough nut to crack for any guided system.
 
3D Anvil said:
Also, it's not just a factor of the stone angle. Most knives don't maintain the same thickness behind the edge from the heel to the tip of the blade. If the stock is thicker towards the tip (it usually is) and you maintain a consistent angle, the bevel will be wider towards the tip. You actually have to maintain an INconsistent angle to keep a consistent bevel width, which is going to be a tough nut to crack for any guided system.
Click to expand...

With the Wicked Edge it's just how it is designed. But yeah, you have to take everything into consideration.
 
There are cheaper versions available:

Some guys even build such a system as DIY project.
Some of them use 3D printers.
 
3D Anvil said:
That Katocut system is VERY cool! Unfortunately, it costs about $2,000!
Click to expand...
The Nowi Pro is around $2.000 but there is also the Nowi Home for around $1.000.

Knife Sharpener NOWI Pro | katocut.com

High quality stainless steel and aircraft aluminum base to minimize unwanted inertia.
katocut.com katocut.com
katocut.com

Nowi Pro Complete Set | katocut.com

Nowi Pro offers you the advantages of free choice of abrasives, angular stability over the entire blade length and a customizable cutting edge angle, as well as the advantage of delivery in an optional impact-resistant, airtight transport & storage case with milled high-quality foam insert to...
katocut.com katocut.com

Knife Sharpener NOWI Home | katocut.com

High-precision components ensure a perfect result, which for the first time gives the possibility of individual sharpening.
katocut.com katocut.com
katocut.com

Nowi Home Complete Set | katocut.com

Nowi Home offers you not only the advantage of a free choice of abrasives and angle stability over the entire length of the blade, but also the advantage of a choice of three fixed sharpening angles, which have been carefully adapted to your area of application. You can choose between a 30Ā°...
katocut.com katocut.com
 
Titanium said:
The Nowi Pro is around $2.000 but there is also the Nowi Home for around $1.000.
Click to expand...
Problem with the Home edition is that you are stuck with a single bevel angle. Also, I'm not sure their clamping system generally would work for many pocket knives.
 
3D Anvil said:
Problem with the Home edition is that you are stuck with a single bevel angle. Also, I'm not sure their clamping system generally would work for many pocket knives.
Click to expand...
As far as I know, it is possible to order the rod with the adjustable angle for the Home version too.
That piece is pretty expensive though.

It can be an advantage to have a fixed angle.
You can't screw up with adjusting the device to the correct angle.šŸ˜‰
 
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