I sincerely apologize for my insistence that my explanation was correct- I had to find a theory that explained why we were seeing a bevel/angle change down the length of the blade but I got stuck on the idea that the explanation was purely mathematical, when in fact the explanation is due to the design of the system and how a particular person uses it. I was confused why the angle cubes were showing no angle change, yet images of blades were showing what appeared to be a linearly increasing bevel width on the straight portion (which means there
has to be an angle change). That made no sense to me.
At any rate, with that theory thrown out it still needs to be explained why we're getting a bevel/angle change down the length of a straight blade (in reality, not in theory). Others have already covered the basics, but here's my take.
Unfortunately, the real reason behind this is
still due to the design of the W.E. and how it allows user input to dictate the sharpening angle the closer you get to the tip of the blade.
Explanation:
In order to use the W.E. correctly you
should not apply any torque to the stones as you move toward the tip with a push stroke or back towards the hilt with a pull stroke. On the W.E. or E.P. if you torque the stones sharpening straight on, it technically doesn't matter- you'll still apply the same sharpening angle. Since the E.P. shouldn't be used off the blade table we'll stop there. But with the W.E. as you sharpen down towards the the tip any torquing of the stones will introduce errors in the sharpening angle (the stones will move out of the sharpening plane seen in the string projection models others have posted). Simulating a push-stroke let's say a person tends to roll the stone counter-clockwise when viewed from above. This will produce a smaller sharpening angle. If you try to counteract that by applying clockwise torque, you may over-correct and apply a larger, more obtuse angle. With no way of controlling for this save experience, practice, or luck, variable angles will be a reality despite the 'precision' nature of this machine. Ultimately, you need to be able to swipe the stone towards the tip while at the same time applying force
normal to the edge at all times. If you sharpen your own knives, this might not be a problem if your stroke remains consistent. It will become a problem when the same knife visits multiple W.E. machines with different owners.
Take for example the following scenario:
Person A takes their expensive and highly prized kitchen knife to a professional sharpener who sharpens it on the W.E. The sharpener sends back the sharpened knife to the owner and is courteous enough to write down and give the owner all the clamp and angle settings in case the owner takes the blade to a different W.E. sharpener. Over time, Person A dulls their knife again but now this time they know a friend who also has the W.E. sharpener. Person A takes the knife to the friend, who clamps it in the exact same manner and angle using the settings from the first sharpener. The friend sharpens the knife, but since they have longer arms, or a shorter sitting posture, or grip, etc, they happen to place
less torque (or none at all) on the stones. The knife is returned sharp, yet it's obvious the inclusive angle is larger and two bevels are now present, the larger original bevel and the new thinner bevel. Person A sees this, notes the knife is sharp, yet might conclude that their friend doesn't know what they're doing. So in the interest of 'doing it right' Person A buys their own W.E. They setup the knife exactly the same using the initial clamp and angle settings. This time, Person A uses a pull stroke (because they know it shouldn't make a difference). After a few pull strokes Person A is greatly confused- there's now a third bevel on the knife! Person A's pull stroke tends to torque the stone clockwise when viewed from above, causing a high angle/smaller bevel out towards the tip. Person A immediately stops using the pull stroke and goes to a push stroke. They observe that the effect is reversed. With that observation, they go about erasing the wide angle but wouldn't you know it- since the diamond stones remove metal so efficiently Person A is stuck with grinding off a whole lot of metal to get back to that nice acute angle they desire.
Meanwhile in a different universe, Person A takes their prized kitchen knife to a sharpener who uses the Edge Pro. After the knife dulls again, Person A takes it to a friend with an Edge Pro who quickly hones the edge back to sharp, retaining the original bevel. Person A, impressed, buys their own Edge Pro and continues to keep their knife sharp, all the while retaining the same bevel and edge angle. Simply because all three users had the benefit of a design that keeps the area being sharpened close or inline with the pivot point, reducing user-induced angle changes.
Unfortunately, while I was wrong in my original explanation, this means the W.E. is much more prone to user error than I initially thought. Which means it loses points in my book because the edge it puts on a knife will be influenced to a great extent by the sharpening habits of the user.
At any rate, I again apologize for my insistence that there
had to be an angle change due to the design of the system, when there is in fact
a higher risk of angle change due to the design of the system, and who in particular is using it.
P.S. Don't celebrate my early death just yet
cbwx34. I still had to take it upon myself to rationalize the observations, self-correct, and admit I was wrong. One theory dies, another takes its place. Both explained the observations. One was incorrect
.
