There are a number of web sites that have detailed info and the history of this method, noted at the end of this article. After sifting through most of them and listening to instructors and fellow students at Palomar College's Cabinet and Furniture Technology Department about various different approaches to this method, I have put together this general guide to using the so-called "scary sharp" method. Throughout the discussion, I'll make references to alternative approaches to certain aspects. I don't think there is one right way. The end result is getting a really sharp tool with a minimum of fuss. I think this is one of the best ways to do it.
A number of aspects of this method appeal to me:
The supplies are cheap, easily replenished, portable and adaptable to your shop arrangements. It's real quick, not as messy as working with wet stones or oil stones. It works equally well with plane blades, chisels of all sizes, spoke shaves blades, etc. A variation of this method - using different grit belts on an expandable rubber lapidary wheel - can be used to do turning/carving gouges, draw knives and such.
Supplies You Need:
A hard flat surface:
I have a piece of 1/4" tempered glass. I think the thinner normal strength window glass would work just as well back up with a piece of MDF. Size? My 30 x 18 piece works out well as I have about a dozen 1/4 sheet pieces of wet/dry from 100 grit to 2000. You can also use a piece about 9 x 12.
Wet/dry paper:
I use 100, 150, 180, 220, 240, 320, 400, 600, 800, 1000, 1200, 1500, 2000. The coarser grits - the 100's - are only used for damaged edges or tools in really bad shape that haven't been sharpened this way before. At the other end, I think the 2000 is not necessary, the 1500 is sufficient for me. The finer grits from 1000 on up are available at auto parts stores where they deal with auto painting / refinishing supplies. On the back side of the glass, I attached different grades of emery paper for those really nasty honing/flattening jobs. I have used it most frequently to flatten the sole of an old hand plane before moving to finer grits.
Honing Guide:
There is no way to consistently hold a blade at the same angle while sharpening without one of these. There are many available. I have two:
(1) the plain-jane vise type (see photo) that will accept both chisels and planes blades from 1/8" up to about 2-7/8" wide. The blade is held very securely in the adjustable vise. It works well if you use it carefully. The down side is that the roller is only 1/2" wide, so you can tip it sideways fairly easily;
(2) the Veritas honing guide accepts blades up to 2-5/8" wide. Its roller is significantly wider at 1-1/4". A single large brass bolt secures the blade to the jig. I find you need to carefully align the blade squarely to the jig/roller and make sure the tool/blade doesn't rotate in the jig while you are sharpening or your edge will not end up being square to the tool. A plus for this guide is a feature that lets you quickly dial in a 1- or 2-degree microbevel at the end of the sharpening process. (Microbevel discussed below)
Adhesive:
3M brand Super 77 adhesive spray works the best for securing the paper to the glass. A very light spray is sufficient. Too much spray creates a soft layer between the paper and glass that causes ripples in the papers, makes the blade catch/tear the paper, etc. It also makes the paper hard to remove and replace. Just use enough to keep the paper down. Some suggest spraying the back of the paper with water rather than adhesive to create a film that will make the paper stick in place.. I find it doesn't work as well as the adhesive. But it you are using a piece of glass and don't have all the necessary grits applied at once, the water approach would be better for adding/removing different grits.
A quick overview of the process.
It will take probably longer to read this than it will to actually sharpen a tool.
The sharpening process involves honing the back and beveled edge of a chisel/blade through the various necessary grits to obtain a mirror-like surface and extremely sharp edge. I say "necessary" in the sense that the first time a tool is sharpened, you may need to start with at 100 grit to remove gouges/nicks in the edge and get the back surface flat. Once you've sharpened a tool, subsequent touch-up work can begin at an intermediate or finer grit, and it will go much faster.
It may to tempting to start at too fine a grit or skip grits to speed up the process. My experience is that moving through all the grits you have available is actually a faster process than skipping some, as you then end up spending more time trying to polish out the marks of the previous grit. Honing at each grit should only take about a minute or so.
It can be helpful to initially flat grind or hollow grind - your choice - the blade to approximately the desired bevel angle on a Tormek grinder or low speed grinder first. Do not use a high speed grinder or you'll surely ruin the temper in your blade. Grind with the blade oriented so the grinding wheel rotation from the tip toward the handle to minimize heat build up in the steel at the tip. Now we're ready to start.
1. Flatten the back.
No honing jig is required at this point. Start the process by stroking back and forth on the back of the blade to get it dead flat. Not the whole back. What I try to achieve is a mirror finish on the edge at least 1/16 - 1/8" back of the tip. So, start at about the 100 grit, hold the back flat on the paper and stroke back and forth until you can see that the striations in the steel go all the way to the tip and are at least 1/16 - 1/8" back. When they do, it's flat. Any un-honed portion is this area now will detract from your final sharpened edge. O.k., now that it's flat, you can move to the next grit. I try to stroke back and forth at a slightly different angle than the previous grit so that it is obvious that I'm smoothing the surface, as the striations of this finer grit will replace the striations of the previous coarser grit.
Continue this process to about 600. Honing at each grit should only take about a minute or two to complete. Next . . .
2. Set your blade in your honing guide for the desired bevel angle.
There are many recommendations for the "proper" angle to hone various type blades, be they chisel or plane blade. Some people claim they can tell the difference in performance with a degree or two variation.
From the Veritas honing guide literature:
Most chisels and plane blades are ground at a bevel angle of 25° as they come from the manufacturer. This may or may not be an appropriate angle for your work, depending on how the tool is going to be used. For example, a chisel that would only be used for paring and would never be struck with a mallet could have a bevel angle of 20° or less. At the other end of the scale, a mortise chisel that would be used continuously with a mallet would require a bevel angle of 30° in softwood and 35° or more in hardwood.To me, 25o to 30o seems like a good starting point for general work. In any event, it can be helpful to accurately measure and record the distance from the blade tip to the honing guide to you can get back to the same angle when it's time to sharpen or touch up the edge.
Bevel Angle Used on Various Tools:
3. Start honing.
This process is somewhat easier with a hollow ground blade, but the difference is not that significant. Similar to the process for flattening the back, start stroking the beveled side of the blade on the appropriate grit. I apply minimal pressure on the stroke as I push away from me (helps to keep the edge and tip from digging in the paper) and most of the pressure on the pulling/ back stroke. Continue stroking and checking the beveled edge for that consistent striation pattern all the way to the tip. When the edge is honed with that grit, move up one grit. Since the blade is in a jig, It is more difficult to vary the stroke angle to be able to see the finer grit smoother out the previous striations. I try to use somewhat of a curved stroke to help tell the grit striations apart.
Continue with this honing up to your last and finest grit. Your reflection in the blade will be as good as any mirror. You've got this thing so sharp now its . . . scary!
That's it!
Now, enjoy the experience of using a finely tuned hand tool.
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