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Woodcarvings by Maura
A sharp tool is a wonderful tool and a point of pride. However, sharpening a knife can be a tough skill for
many to learn.
THE NO NONSENSE JOOLTOOL REVIEW (click here)
It is important to take safety into consideration when sharpening. You are dealing with sharp edges, flying
grit and high speed revolving wheels. Pay full attention to what you are doing. Safety glasses are recommended. Keep hands clear of all machinery and handle your tools with care.
There is a saying, that a dull knife has hurt more carvers than a sharp one ever will. A dull knife does not cut
in the manner intended and is more prone to slipping. A cut from a sharp knife will be a cleaner cut than from a dull one and will heal faster.
Sharpening supplies can include power sharpening systems, sharpening stones (natural and manmade), strops, honing wheels- leather, paper, felt or cloth (which you can attach to a hand drill, grinder or drill press) and buffing compounds. There is even a method of sharpening which involves attaching various grits of sandpaper to a thick piece of glass or ceramic tile.
There are some very nice and easy to use sharpening systems on the market and some of them you will pay dearly for, but sharpening supplies do not need to be expensive. A new carver should invest the time and energy into learning to sharpen, even before he learns to carve because if your blade is not sharp, it will make carving difficult and frustrate you . Sharpening is the one thing in carving that you will repeat thousands of times. Multiply that by the number of edged tools you own.
Sharpening for Dummies
Concepts you must grasp:
|Grinding, whetting, honing and stropping are not the same.|
|They are different steps in producing a sharp edge.|
|The entire sharpening process involves starting with a grainy surface and then stepping down to less|
|grainy surfaces until you reach a virtually smooth surface.|
|Compound is a chalky substance, which will add a bit of grit to the surface you are using. Generally,|
|the darker the compound, the more grit the compound will contain.|
|The current shape the blade is in will determine what grit you need to start at. Grinding should only|
|be done when the blade is chipped, malformed or extremely dull.|
If you look at the edge of your knife, chisel or gouge, you will see a bevel. The bevel is the angle which is on the edge of the blade, usually this bevel is between 10 and 25 degrees. bevels of 10-20 degrees are used for softer woods, 15-25 degrees for carving harder woods. Some tools will have 1 bevel, others will have 1 on each side and both bevels must be sharpened. when sharpening a tool with only one bevel, first you must dress the back (the side without a bevel) by keeping the blade perfectly flat against the stone, using constant movement. When the back of the blade is perfectly flat you can proceed to sharpen the bevel or bevels.
Grit, very simply is the number of hard particles per square inch of surface
36-250, Very Course........................Regrinding of damaged edges
250-400, Course................................Removal of nicks and slight damage
400-1000, Medium.....First stage of obtaining a fine edge, final stage for rough work
1000-4000, Fine........Second stage for fine edge, final stage for general purpose
4000-8000, Very/Super Fine..............Final stage for fine edge on carving chisels
Higher grits of sand paper can be purchased at auto supply stores, higher grit wheels and stones can be purchased at specialty stores that deal with woodworking or carving.
Using any hard sharpening stone (manual or mechanical), you are going to line your chisel up on the stone so that the bevel is laying flat against the stone. then you will use a slight downward pressure and holding the blade with the bevel correctly angled against the stone, constantly move the edge of the chisel or knife across it. For hand and machine grinding, you will push the blade into the stone as if trying to slice off a very thin sliver, repeat this movement over and over. For machine whetting, the blade is not being pushed into the stone, but will ride on top of the stone with the wheel revolving away from you at the top of the wheel. Hand whetting will require that you pull the blade back toward you over the stone. When using a mechanical sharpener, it is important that you monitor the edge of your tool making sure that you don't let the edge become overly hot. You can burn the edge of your blade which will destroy the temper (hardness) of the edge. This can be avoided by removing the tool from the stone and letting it cool a bit before applying it again. If you do burn an edge (you will see a discoloration of blue, black and brown), simply sharpen it again until you remove all the discolored metal. You can also use water on the stone to help keep the temperature caused by the friction, down. Some stones say to use oil but I find water works just as well or better and does not gunk up the stone.
As you sharpen, a small burr (very thin metal particles clinging to the edge of the blade) will start to form. A blade is sharp when the burr has formed along the entire edge of the tool or when you hold the edge up to a light and can not get a reflection off the tip when looking directly into the blade.
After you have sharpened your blade you will proceed to hone your blade. Honing is done on a softer material than stone. I have seen many things used, from cloth or felt wheels, to leather strops and pieces of flat cardboard. I prefer to use a cloth wheel which is mounted into my drill press. You apply a buffing or honing compound to the surface of the wheel and holding the blade against the wheel, with the wheel spinning away from the tip, proceed to buff the tip. Buff until you have removed the entire burr that formed in the sharpening process and until you have achieved a mirror finish on your blade.
If a blade is properly sharpened, you will not need to sharpen again for a long time, unless you have chipped the blade. I find that chipping of the blade is mostly caused by dropping a tool, tools banging against each other in your toolbox, a tool rolling off the bench or the improper use of the blade as in prying wood off, rather than cutting into it. A little care taken to see that these "accidents" don't happen will go along way in saving you from having to sharpen. Honing the blade often during your carving process will keep the blade sharp.
Sharpening rounded edges as on a gouge takes some time to get the feel for, but is done in the same manner as a straight edge. You rock the edge against the stone as you are sharpening so that the entire edge makes contact with the stone. Take care to keep the right angle of the bevel flat against the stone.
When sharpening a v-tool, keep in mind that there are three separate bevels to this tool, two main blades and a small edge in the center. Each edge must be sharpened independently.
The final step should be to polish the entire bevel and back of the blade on a soft cotton or cloth wheel. If you are using premium steels, you should be able to attain a mirror finish. This is important. Any irregularity in the surface of the bevel will translate into scratches in your carving.
There are different methods for determining if a tool is sharp. Some like to see if they can shave the hair on their arms and others drag the cutting edge over a fingernail. It will slide smoothly with no drag when sharp. The method that I prefer is to stand underneath a bright light, a bare bulb works best. Look directly down into the cutting edge. If any light reflects off the edge, it is not sharp yet.
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contact meMaura Macaluso Staten Island, NY 917-494-0008
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©2005 Carvin' in NYC