Blade Sharpening Demystified by Red Rock

There is always so much opinion about sharpening anything especially by people who own anything with a blade, but very few people really seem to understand what is going on with "restoring an edge" to a blade. In ice auger blade sharpening, you always hear that "that angle is hard to get right". But if you look at a brand new blade closely, you'll note that you have been looking at the wrong part and drawing all sorts for incorrect conclusions. Here are the facts. Click on a picture to see a larger version of it. Regardless of the style of blade, the principle remains the same for sharpening.

Shaver Blades

The bevel that I've highlighted with the little arrows is the slant that has been ground away during the manufacture of this blade. That is NOT the cutting edge of the blade. The angle of the bevel is maybe 15%. It could be some other angle as well. The only reason it exists as it is is because that's the angle they set up at the factory. My guess is that it allows the final step of sharpening to put the edge on blade that does the work. So, the big obvious bevel is not the bevel that cuts the ice. Oh it does eventually after the lead edge does wear down, but the leading edge on the very bottom side is what cuts. The bevel behind the edge backs it up to give it strength to allow it to plow through the ice without deforming. Imagin how much pressure is behind the final edge of the blade as it rams through the ice.
So, while every sales person in every sport shop talks with authority about the bevel and how hard it is to achieve, do you ever hear them talk about the part of blade that actually digs in and cuts? If you observe the circled part of the blade or anywhere along the edge, you'll note about a 1 to 1.5 millimeter wide region that comprsies the edge of the blade: the cutting part. The angle of this edge looks to me to be about a 40 degree angle which is pretty blunt relative to a 15 degree angle. Nobody notices that.
Here's a blow up of the 1 to 1.5 mm edge. All the rest behind it doesn't really pertain to cutting ice other than serving as a backup or reinforcement to allow the edge to be plowed through the ice. Everybody worries about the top side bevel. This is the important side of the blade. The bottom. The bottom most edge is what cuts through the ice. If the bottom edge is rounded upwards (called "dull"), it is not going to attack the ice. It'll ride around on top. The blade then needs to have it's edge restored.
   
   
Here's what's going on with the blade when we get a dull one and after has been resharpened. You can pretty much see what the goal is and how the bevel on top is not all that significant when compared to the edge that is formed on the bottom of the blade through grinding. The "edge restored" is what we want. Who cares what the bevel on top does?

The problem is that most people will sharpen the top but not enought to take the blade off to the "non-ski" portion. That's fairly hard to do consistently without a grinder set up correctly and an eye for the dull part. Then, after grinding away on the bevel, there is a bur that hangs down. Everybody flips the blade over and tries to peel off the bur with a grinder. They turn thier brand new edge back into a "ski" and we're back to square one. The blade is dull after all that dinking around.

Chipper Blades - Jiffy models and Strikemaster Mag 2000, etc.

Chipper Blades cut on the exact same principle as shaver blades only upside down. The business end of the blade is the top which is helad in place at an angle to the ice. The bevel that the chipper owners worry about is on the backside of the blade and does not come in contact with the ice. It serves the exact same purpose as it does on the shaver blade above which means it is ground off to expose an edge. The edge is what does all the work in cutting the ice.

Home sharpenings tend to make the same mistake in restoring that bevel on the non-cutting side of the blade. But then, they take the bur off of the cutting edge and dull it right back to square one. The bur has to be stropped only.

The biggest problem with single-blade chipper augers is that when they ice up or become dull, the owner of said auger impatiently picks up on the spinning machine and drops it in the hole to knock off the ice and make the dull blades catch. Doing this repeatedly makes the blade catch until the weight of the auger has finally pounded that single blade upwards in it's bracket. After it is completely dead in it's ability to cut ice because it is dull and tipped up from being pounded downward, the own decides to have the blade sharpened.

We sharpen the blade and send it back. The owner re-installs the nice sharp blade and

discovers that it just spins on the ice. Of course, he "never" pounded that auger into the hole prior to it having it's blade resharpened. Oh, no...not him. Plus, it cut just fine prior to being resharpened. That begs the question as to why he sent that blade in to sharpened? Because it wouldn't cut anymore and was just spinning on the ice. Funny, it got worse after he dropped the auger inthe hole repeatedly. He wonders why that is?

If the blade-mounting housing is bent even a little, then taking a little off the blade to expose a good edge (1-2 millimeters) would have an effect on the blades ability to cut after being resharpened. The edge would simply not bite the ice and it would spin around in circles just like it did prior to being resharpened. So, the owner, now all ticked-off at us, heads down to the local sport shop where they don't sharpen anything, but they know those blades have been resharpened and, of course, completely ruined. The first thing they point to is the "bevel" on the back side of the business end of the blade. They declare the blade "ruined" because the angle on the backside is not the same as the original. For some reason, this angle is more important than the cutting edge to everybody. As a result the owner needs to buy a new blade - which he does. He, of course, doesn't mention that the auger wouldn't even cut prior to sending in the old blade for resharpening and of course, the sport shop staff doesn't ask. They just want to sell him the blade and look like a hero, solving the man's problems and blaming the guy who wrecked that blade.

He goes home, re-installs the new blade and lo & behold, it works, sort of. The new blade is at it's longest length. It reaches the ice despite the bending upwards of the blade housing due to icing/not-cutting the old blade provided. It'll work, until it gets a little dull or has ice built up on it. A couple more poundings in the hole, and that new blade will miss the ice as well. It's inevitable.

Meanwhile, we catch heck for "ruining the blade" based on what the non-sharpening-anything-at-all sport shop said. You are not getting a new blade from us. We didn't wreck the old one and have a pretty good idea what happened. There is absolutely no way that we would be able to know if your auger was screwed up and malfunctioning. We haven't developed our 6th sense all that well. We hope it works, but in reality have no idea. For all we know, you may have driven over your auger with a tractor after using it for drilling post holes last fall. (Yep - we've actually seen that.)

Summary - We resharpen blades. We also icefish and use the blades ourselves. We observe LOTS of ice fishermen who are too cheap/lazy to take the time to get new blades on their machines and instead resort to lifting-dropping the auger in the hole. Pounding is almost a universal response to icing and a dull/bent blade when it's not working. Pounding/dropping the auger in the hole makes things worse. It's like ramming wood into your tablesaw blade because it doesn't cut.

Our sharpening is always on it's mark. Your auger may not be as such. If the angle is changed in the blade mounting bracket/region, it will not cut. Worrying about a percieved bur on the flat side of an auger blade is a waste of your energy. It does not affect a thing in cutting ice. We aren't sharpening surgical tools here. It's an ice auger and it either chips or shaves ice which is essentially the same thing. If the cutting edge does not dig into the ice, it will run around in circles cutting nothing. It's not rocket science.

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