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Sharpening Tools

Like many of you I'm sure, I am often shocked when visiting someone who needs something fixed and ask if they have a plane or chisel. I generally find that I have screwdrivers that are sharper than most chisels and most planes are too rusty to even serve as cheese slicers. ;-(   Having sharp tools to work with will make any job with wood SO much more pleasurable and doable, so let's run through the basics.

Sharpening Planes and Chisels

There are typically just 2 or 3 steps.
First of all, we need to grind the blade back to the right angle. Then we need to sharpen the cutting edge on a stone and finally, in the case of the plane, correctly adjust the blade position.
This of course first assumes that we've bought a tool with a decent steel blade. You can usually tell right away when sharpening the edge on a stone, what sort of steel you have, just by the noise. When it makes lots of grinding noise then it's typically a soft steel that will not hold its edge for more than a few uses, whereas a hard steel makes far less noise but takes longer to sharpen. Pay a little more and avoid the cheapies—it's worth it.

But first to the initial grinding. The blade needs to be first ground back about 20°, so that the final honing is still not much more than 25°.

[Typical Western jack and smoothing planes (9"–14"), have blades set at 45° to the plane base. Because they mount against a cap iron designed to curl the shavings, the sharpened part is actually placed on the underside. So the blade shaves off from a constant 45° at the top, with the angle of sharpening (typically 25–30°), dictating the clearance under. From this one can see that IF the blade is not first ground to a fairly fine angle, then it's easy to get close to 45° for the final honing and at that point, the plane would only slide over the wood and NEVER cut! (See sketch farther down.)
By contrast, a 6" block plane, has no cap iron and the blade is set in the plane with the bevel on top—working more like a chisel. For this reason, the basic blade angle built into a typical western block plane is much lower (30°) as the upper cutting angle is 'added' to that—so in fact, works more like a fine surface scraper. But again, the sharpening angle must still be kept fairly fine, or in this case it could get too vertical.]

Although the best way to grind a blade is on a large diameter stone that turns in a water trough, most of us do not have space or time for this, and resort to an electric grinder. You'll need at least an 8" diameter stone with ¾" width for a good job. (With careful control and movement, I've occasionally had to manage with less; but the smaller the stone, the more concave hollow is cut into the blade and this removes rigidity at the cutting surface, which is not good).
Have a container of water handy, so that you can keep dipping the blade to keep it cool.
WARNING: Take the last line very seriously, as if the blade tip overheats, you'll lose the temper and significantly reduce its hardness. For this reason, do not grind the blade right down to the fine edge or it will CERTAINLY overheat.

Before starting the motor, place the blade on the stone to check what height you need to hold it in order to get the right grinding angle—as seen from the side. Take a note of where the blade tip comes to in relation to say, the protection guard. For this small grinder, it was about 1" below the start of the guard.


With the wheel up to speed, place the blade on the rest so that the tip will be at the right height and once grinding, work with your thumbs to slide the blade side-to-side on the tool rest, so that the blade is evenly cut across its width. Do not press too hard or you risk to overheat the blade and destroy its original hardness. Pressing too little will not work either, as then you polish rather than grind the surface. Experience will teach you.

Dip in the water and check your cut often.

The final cutting edge is achieved by honing on a good quality stone. Do not waste time with cheap, soft and rough grey stones (that we used to dub 'carborundums), but invest in a fine, harder, brown, 'India' or 'Arkansas' stone. As these are not so cheap, make or buy a holder for it of wood, so that you can grip it on your bench or in your vice without contacting and damaging the relatively brittle stone.
www.bestsharpeningstones.com/catalog/Hard_Arkansas_Stone.htm
www.bestsharpeningstones.com/catalog/Norton_1000_8000_Combination_Waterstone.html

I'd suggest a light oil on the Arkansas stone (even a honing oil) or water on the Norton stone for lubrication. An effective 'India' stone is also available from Norton and typically has a coarse and fine side—though I use the fine side almost exclusively. A mix of engine oil and kerosene works well on most stones and it's important to keep the stone oiled or it will dry out.

If it's a chisel, then I recommend a grip as shown in the photo at left (below).


If it's a plane iron, then I suggest the alternative grip in the other photo.
Either way, the idea is to maintain a constant angle as you move the tool up and down the stone and also, to move the cutting edge in circles or figure-eights, so that the stone does not get worn down only in the center of it. Moving your elbows somewhat with your hands can help to keep the angle constant.

If you really have a problem with maintaining a constant 25° angle, then I recommend you buy a sharpening guide. Here's one for Western style blades for just $17.
www.japanwoodworker.com/product.asp?s=JapanWoodworker&pf_id=11%2E209%2E22&dept_id=13113

Once you have honed for a while and start to feel a small burr on the back of the blade edge, turn the blade over and with it pressed totally flat on the stone, take that burr off. The blade edge should then be almost as sharp as a razor blade—but if there is no real 'edge' to it, repeat the last two steps, until you do get an edge. If the stone is too coarse or soft, the cutting edge will never be satisfactory in my experience, so first, get yourself a good stone and look after it. It's VERY important to move narrow chisels around on the surface or you'll soon have a dip in the stone and then 2" wide plane blades cannot be sharpened straight again.

Once a plane iron has been sharpened, you need to remount it with its shaving curler or cap iron. For fine planing work, the cap iron needs to be set fairly close to the cutting edge (less than 1 mm)—for more aggressive cutting, it can be a little farther back (say 1.5 mm). After installing in the plane, turn the bottom uppermost and hold up against the light. This way you can see how far the cutting blade is projecting and whether it's parallel to the plane bottom surface. Use the lever to straighten the blade and then the thumb screw to have just a VERY small projection of blade. Then try some shavings and if it's too hard to push, lift the blade out more. If it's not cutting, you either do not have enough blade out or the blade is not sharp. OR the final cutting angle is greater than 45°. In the latter case, this would mean that the heel of the blade is sliding on the wood, as shown in this sketch.

How often you sharpen will depend on what wood you use it on and whether there are knots, lots of end grain etc. but I rarely use a plane for more than an accumulated 30–45 minutes without resharpening. With the blade removed, get accustomed to feeling your thumb over the blade edge and you'll soon get to know what sharp really is.
Do not have too much blade projection. It will take too much physical power to push it .. and NEVER park your plane with the blade down on the bench! Always, lay it on its side so that the precious sharp edge is protected from foreign things on your work bench. Also, never use your chisels as scrapers or even worse, as screwdrivers!

Small blades like those for spokeshaves, are best fitted into a small holder for sharpening. You can make such a holder from hardwood, with a snug slot in it for the small blade. You'll then be able to sharpen it as a chisel.

Sharpening Drills

For sharpening drills there are special tools and holders to assure the right angle, but for many years now, I've done this quickly and successfully without the aid of such things.
Here's how. To learn the feeling, I suggest you start with a drill of at least ¼" (6 mm) diameter. A typical drill has two cutting edges that need regular attention.
Locate them and start the grinder. Use the finer of the 2 stones. Approach the stone with the drill at around 45° to the stone. Keep your index fingers under the drill and rotate the drill so that one of the cutting edges is uppermost and close to the stone. As you slightly lift the drill tip across the grinder stone, rotate it about 90°. This will take practice, but when done correctly, the side view of the drill should look like this, with the point meeting in the center with a short, sharp ridge.


There should be a slight slope at the drill, with the left edge of the drill, now being slightly more cut back than near the lead edge. Remove any burr at the cutting edge with a small fine file used vertically, and then repeat the other side of the drill, making sure that the grinding is equal both sides.

While it's hard to explain in words exactly the movement required to get the result shown, I note that I do most of the twist with my left hand and most of the lift, with my right hand. Perhaps that will help.

Practice with a drill of ¼" or larger and then graduate to the smaller ones. Once you learn the right feel of 'turning and lifting', you will be able to quickly sharpen drills as small as 332" diameter.

Always take the time to create 'sharp tools'—makes work MUCH easier and more enjoyable.


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