| All About Chisels |
From "Ask DIY"
episode ADI-305 |
|
|
|
advertisement
|
Q: I have a drawer of old chisels that my father gave me. How should I sharpen and care for them? Can you help? A: (from Bruce Johnson, Ask DIY Woodworking expert) Chances are, you've got some good-quality chisels in your collection. Many older chisels were made with a higher quality of steel than their newer counterparts. But before you start to sharpen and care for your chisels, you'll need to know a little about their various parts and general design. Here are some points to bear in mind: - Many new chisels like the one shown in figure A will have plastic handles. For wooden handles, you'll want to rub some tung oil on the handles to prevent them from drying out. Inside the handle, the blade's lower extension (figure B) should reach at least 1" to 1-1/2" into the handle's center. This will ensure a good contact between the handle and the blade.
- Some chisels will also have what's known as a shock washer (inlaid in the top of the handle shown in figure C) to absorb the shock between the blade and the handle.
- Other parts of a chisel include the following: the neck (the area indicated just above the handle in figure D), the shoulder (the angled portion of the neck that gradually widens into the blade), the back (distinguished by its beveled sides), the face (the entirely flat side of the blade) and the bevel, which is the blade's tip and cutting edge.
- When purchasing a new chisel, keep in mind that the price will be determined by the width of the blade, the quality of the steel and the quality of the handle. (If the handle falls apart, the chisel won't do you much good!) As with most tools, it's generally best to buy the highest-quality chisel you can afford.
- At the time of purchase, the chisel blade will be protected by a thin coat of lacquer, which has been applied by the manufacturer to prevent the chisel from rusting before it's sold. This lacquer must be removed prior to sharpening the chisel, however, or it will clog up your sharpening stone.
- To remove the lacquer, dampen a cloth will lacquer thinner and rub it firmly over the entire surface of the blade (figure E). Although you won't see much immediate difference, this step will ensure that the coating is removed for future use.
- Chisels require regular sharpening to keep them in top condition, so be sure to purchase a sharpening stone when you buy your chisel. Sharpening stones will generally have a two-color composition -- the light color usually represents the fine- grit side, while the dark-colored side is composed of a coarse grit (figure F).
- Before using your sharpening stone, you'll need to apply a fine oil to the stone's surface (figure G). This will prevent the small filings from becoming embedded in the stone and damaging the grit. Once you've applied a bit of oil, rub the face of the chisel in a circular motion on the oiled area of the stone's coarse, dark- colored side (figure H). This will ensure that the face is perfectly flat; most chisels have a slightly uneven face when they're shipped from the factory.
- Next, you'll need to sharpen the bevel. To do this, simply apply a small portion of oil to the fine-grit (light-colored) side of the stone and rub the bevel against the stone in a circular motion. This will ensure the bevel is at its sharpest -- ready to go to work!
- For older chisels that have been stored away in a drawer or toolbox for a while, taking the blade directly to the sharpening stone won't do any good. Chisels like these have incurred numerous nicks to the blade and will need to have the existing surface of the metal ground off before they can be honed to a sharp, fresh edge.
- To do this, you can use either a bench grinder or a stationary sander. (Important reminder: Be sure you're wearing safety glasses whenever you sharpen or use chisels.) If you're using a bench grinder, press the flat side of the bevel gently against the grinder wheel, moving it slowly back and forth (figure I). This will allow the grinder to reveal the metal just below the existing surface.
- If you're using a stationary sander (figure J), follow the same technique used with the bench grinder, but move the blade in a slightly circular motion instead of side-to-side.
- It's important not to let your chisel blades become too hot, as this will weaken the metal. If the blade does become overheated, however, don't immerse it in water to cool it -- this will create hundreds of small cracks along the edge of the bevel. Instead, hold the heated chisel blade against a cool chisel (figure K), which will draw out the excess heat.
- Once you've removed the existing surface of metal from a damaged chisel blade, you're ready to hone the edges on the sharpening stone as described above.
- To test the sharpness of the bevel, drive a 3/8" dowel into a block of wood, allowing about 1" to protrude. Then place the blade (face up) against the side of the dowel at the point it connects with the wood block. Firmly (but not too forcefully) strike the end of the handle with a rubber mallet; the end of the dowel should break off (figure L) after two or three hits.
- Before storing your chisels, replace the small plastic cap (figure M) that accompanied the chisel when it was originally purchased. If your chisel wasn't sold with a protective cap, you can use an old glove instead: just insert the chisel into one of the glove fingers (figure N). Placing a chisel in each of the fingers is a great solution for those who own several.
But whatever means you use to protect your chisels, don't forget to do it. With all the work involved in sharpening a chisel blade, it's worth taking an extra minute or so to preserve your efforts!
RESOURCES :
The Complete Manual of Woodworking
Author: Albert Jackson
Publisher: Knopf
ISBN: 0679766111
Woodworking Basics: The Essential Benchtop Reference
Author: William Perkins Spence
Publisher: Sterling
ISBN: 0806909412
176 Woodworking Projects: A Workbench Treasury
Model: 0806965282
Author: Workbench Magazine
To order this title from Amazon, click here.
|
)
)
)
)
)
)
)
)
)
)
)
)
)
)
