Saturday, August 31, 2013

How Do You Go About Your Sharpening Now It's A Year On?

This is the question posed by Mark Rhodes last week in the comments section of my post Hollow-Ground DuoSharp Sharpening. That post was motivated by what I had read on his website and his postings to the UKWorkshop Hand Tools forum, where I wanted to try out his method. Wow, it's been a year already?!?

The quick answer is that perhaps 90% of the time now I do my sharpening freehand on Norton oilstones, either forward-and-back forming a slightly convex bevel, or side-to-side forming a double bevel. For most of the remaining 10% of the time, I use Ohishi or Norton waterstones or DMT Duo-Sharp diamond plates. I do the last little bit very rarely on my hand-cranked grinder or sandpaper on glass or polished stone tile.

In all cases I finish up with a leather strop dressed with green or yellow compound. I've been doing most of my back preparation using the sandpaper on tile method.

So while the bulk of it is with the oilstones, I'm actually using a whole bunch of different methods. This is for several reasons.

First, I'm sharpening for 3 situations: doing my own woodworking, doing woodworking demonstrations, and teaching classes.

Second, I'm dealing with a range of tool shapes, from long narrow chisels through wide plane irons to stubby wide spokeshave irons, plus a variety of specialty plane irons.

Third, I prize versatility for its own sake. I want to be able to sharpen no matter the tool or the sharpening setup.

Those are the rational forces that come into play, that also get mixed in with a few irrational considerations.

Each of these methods is effective, producing a sharp tool. While each has its quirks, I don't find that any of them stands out appreciably in terms of results, time-efficiency, or cost, particularly given the range of situations I'm trying to cover. The time overall for any of them is only a few minutes.

For my own work, my interest is in learning traditional methods, which in this part of New England is based primarily on traditional English methods. For me oilstones represent that tradition. Sure that's a bit of foolish romanticism, but if they could do it this way 200 years ago, I'd like to as well. The historical connection is probably murky, given that I don't have a traditional large grindstone and modern manmade oilstones are probably more advanced abrasives than the old ones.

When I do demonstrations, people are invariably drawn to the oilstone method. They recognize it as old-school, remembering a grandfather doing that. It's that same nostalgic and romantic connection to the past and to the craft. They're also fascinated that even in the modern high tech era with all the latest space age materials and gadgets available, the old method still holds its own. That's what makes demonstrations fun and engaging, bringing people back to the satisfaction of working with their hands.

Teaching is a much different situation. Students have a variety of motivations. They often come to class with a particular sharpening setup they want to learn to use. Some have no set idea and want to try different ones. So I adapt my lesson to their needs. For that I need to be proficient in all of them. I try to digest down the common principles, then apply them to each one.

As a practical matter, I find the oilstone setup well-suited for portability, especially once I built my portable sharpening station. I find the waterstones least portable, particularly the type that require pre-soaking; waterstones seem to be messiest. Diamond plates are also quite portable, but are furthest removed from that traditional connection, one of those irrational considerations.

Tool shape doesn't really dictate which sharpening setup I use, but it does drive the decision to sharpen freehand, and which sharpening motion to use. Freehand sharpening allows me the most adaptability to the situation, as opposed to jigs and guides, which are optimized for specific ranges of shapes. Some tools and specialty irons get quite awkward to hold, so using a different motion works better.

For most tools, I use a forward-and-back motion with a slight convex motion. I originally wrote about that in The Grimsdale Method, and continued to work that way based on Paul Sellers' book. Usually I go for just a subtle convexity. All I need to do is extend and retract my arm while holding the tool consistently throughout the motion; that mechanical extension is just enough to vary the angle, leaving a slight rounding in the overall bevel profile.

I usually demonstrate it with a more exaggerated convexity, pointing out that trying to keep it flat will still usually end up slightly convex. Rather than fighting that tendency, the convex bevel method embraces it. The key is to cross the edge at the desired sharpening angle. I use a visual sight block to align the tool to the angle.

For some tools, I use a side to side motion with a double bevel. I find this motion makes holding a particular bevel angle a little easier. With narrow blades it can be hard to prevent sideways rolling, but for stubby spokeshave irons, wider than they are long, it's ideal. When I'm working the primary bevel, I'm not too concerned about what actual angle I end up with. When I'm working the secondary bevel, honing the actual cutting edge, I take more care.

So using multiple methods allows me to cover a wide variety of situations. If one's not working out for me, I can switch to another.

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