I'll "3rd" Leonard Lee's book...and failing that, I'll highly recommend his DVD! A picture is worth a thousand words...a video is the next best thing to a hands on tutorial.
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I'll "3rd" Leonard Lee's book...and failing that, I'll highly recommend his DVD! A picture is worth a thousand words...a video is the next best thing to a hands on tutorial.
I'll take a shot at this. Trying to make it as simple as possible, I’m bound to over simplify in some places, but take it for what its worth. Sharpening is a natural companion skill to woodworking. You won’t be any good at woodworking without being able to sharpen your own tools.
There are two main things you are trying to do in sharpening.
First make the cutting edge of the tool the right shape. Usually you can tell what shape it is supposed to be by looking at the tool. Most of the shape will be there. You remove steel to restore that shape. This can be done with a grinder, file or rough sandpaper. At this point, you are restoring the shape by grinding out any flaws in the blade such as nicks or places where it is misshapen. When using a grinder you need to be especially careful to avoid heating the steel enough to change its color. If you change its color the steel will loose its temper and be soft. Also at this point, you need to watch carefully to make sure the edge is even and straight. I find a honing guide and a small square to be very helpful.
At this point, you have something which from a few inches away looks like what you are trying to achieve. If you look at the edge closely though, especially under a magnifying glass, you will see that the edge is a jagged mess of scratches and if you drag it along your finger nail, it will feel rough. It might work for some purposes, but it’s not a fine woodworking tool. What you want is for the edge of a blade to be the intersection of two smooth surfaces. Those two smooth surfaces meeting at a line make a sharp edge.
Your second task is to smooth those surfaces while maintainng the shape using successively finer abrasives. Many different options are available. I use the Scary Sharp system because it's cheap, effective and flexible. Before you move to a finer abrasive, be sure that all the marks from the earlier abrasive have been ground out. I find it helpful to occasionally examine the surfaces I’m grinding with a 30 x magnifying glass to make sure I’m progressing through the grits properly. Eventually, you will have two mirror surfaces meeting at an edge so fine that it parts wood with little effort.
You may want to put on a micro bevel to strengthen the edge. That’s just a little secondary shaping of the blade which makes it slightly blunter but more durable.
There’s a lot more to it than that, and a big part of it is technique and muscle memory which allows you to move the tool against the abrasive with the right force and the right angle. A wide variety of jigs and fixtures are available to substitute for or assist technique, energy and time, but the basic principles stay the same.
Luke,Quote:
Originally Posted by Luke McFadden
I <<whatever number we're up to now>> getting Tom Lie-Nielsen's and/or Leonard Lee's sharpening books; both excellent. Ian Kirby's book on sharpening with water stones is also very good.
It does not take very long to learn how to sharpen, and as others have already commented, it's an essential woodworking skill.
Quick and dirty:
Spokeshave and draw knife -- go back and take another look at Bob Smalser's tutorials on sharpening them. They're the best and most straight forward I've seen anywhere.
Plane irons: There are numerous ways to do this; all of them work. Here's mine:
I sharpen freehand with Japanese water stones. If you use any type of sharpening stones, make sure that they are flat before you begin.
Square (90°) the leading edge of the iron with the sides, if necessary; you can use a grinder, a file, or a coarse stone to do this. If you use a grinder, be careful not to burn the steel and draw the temper.
On the flat side of the iron, start with your coarsest stone and work your way up through the grits to your finest stone. You want to polish the non-bevel side of the iron for about an inch (more or less -- it doesn't have to be exact) back from the cutting edge. You're looking for a mirror polish here. You usually only have to do this once. A few honing strokes on your finest stone on the flat side of the iron will maintain the mirror polish in future sharpenings.
(One reason that you want the back of the iron mirror polished is to match the mirror polish that you'll be putting on the bevel side of the edge. This polishing largely eliminates the tiny/microscopic serrations that would otherwise be there, and which are prone to break off in use, hastening the dulling of the iron. If both intersecting surfaces are polished to the same degree, there are fewer and smaller serrations to break off; this helps the edge last longer, all other things being equal. You want to polish at least to the approximate equivilent of 6000 or 8000 grit on Japanese water stones, regardless of the method you use.)
Once the flat of the iron is polished, flip it over to the bevel side. Again starting with your coarsest stone, work your way through the grits up to your finest stone. Again, you're looking for a mirror polish.
I like my bevels honed flat, and generally don't use a micro-bevel; others prefer a hollow grind and some also a micro-bevel or back bevel. All of these variations work, so it's mostly a matter of personal preference, more than anything else. None of these methods or end results are "wrong" as they all cut the wood.....so there's really no need to get wrapped up in whether a micro-bevel is superior to a ..... and so forth. Find one that you like and works for you and stick with it.
Anyway, back to the subject at hand.... One technique that makes it easier to keep the bevel flat on the stone at a consistent angle is to lock your arms -- that is, lock your wrists, elbows, and shoulders with your arms extended. The "lock" you want is a "relaxed" lock, not the muscle-tense-hands-shaking, white-knuckled, death-grip lock. Then step back slightly and position your feet like you're walking. Now, rock the bevel forward until it is flat onto the stone, lock your arms, and move your belly button forward and backward (from your hips, using your legs to move) about two or three inches. Your iron should remain flat and at the same angle throughout this motion. After doing this for a couple of minutes, you'll get the feel for the bevel on the stone and will be able to relax a bit and use a bit more arm motion if you want to.
Once you have the basic sharpening completed, then you can add a micro-bevel and/or back bevel and camber the iron if desired.
How sharp is sharp enough? There are many answers to this question. My answer is that if it will pull shavings off of end grain pine, then it's sharp enough for almost any woodworking operation.
It will take a few tries to get sharpening down, but don't give up. Once you learn how to sharpen, you'll find that your woodworking improves substantially -- because sharp tools work so much better and easier than dull ones, and you can concentrate on guiding the cut instead of trying to force the (dull) tool to work. And, if you find that freehanding it just won't work for you, then get a sharpening jig and learn to use it; once you become proficient with the jig, you can give freehanding another shot if you want.
Good luck!! I hope that this long-winded explanation is of some use to you.