Sharpening Tools Used in Carpentry (Automatic & Manual)
Sharpening Tools
For sharpening, natural stones such as Washita or Arkansas produce the keenest edge, but they are very expensive. Man-made stones are produced from vitrified aluminium oxide or silicon carbide grit.
The resulting stone is harder than natural stone, but it does not normally have such fine grit or the close density which characterizes the very best of sharp edges. The grit is graded as coarse, medium, and fine. Coarse grit stones would be used to regrind a damaged blade; medium and fine grit for sharpening.
Bench Grinder
Size: wheel size- (125mm, 150mm, 175mm, 200mm and 250mm); power- (2950rpm to 3600rpm)
Material: various
Accessories: grinding, wheels, wire wheels, buffing mops
Use: to sharpen tools and clean up metal
A bench grinder can grind the cutting edge of tools square and sharp, remove burrs from the anvil ends of cold chisels, repair screwdrivers, drill bits, and the point of punches, sharpen scissors, and polish metal-work. Most bench grinders have an electric motor that drives two wheels simultaneously, so you can mount wheels of different abrasive or grain at each end, or couple a wire wheel or buffing mop with a medium grinding wheel.
The grinder must be bolted firmly to the benchtop and must be fitted with wheel guards, eye shields and tool rests at all times. Grinder size is specified by the maximum size of wheel it can take. Choose a 125mm to 175mm grinder for use in the home workshop.
Bench Grinder
Bench Grinder Wheel Assembly
Drill Bit Sharpener
Size: takes drill bits 3mm to 9mm
Material: various
Use: to sharpen twist drill bits
The electric drill bit sharpener makes the normally trick job of regrinding drill bits easy. Fit the bit in the appropriate hole in the top plate. Turn the bit clockwise until it stops. Holding it in this position, depress the starter switch and apply a light to medium pressure on the drill bit for 1 to 3 seconds.
Do not revolve the bit during the grinding. Remove the bit, revolve it half a turn so that the sharpened side faces the center of the top plate, and replace it in the hole. Repeat the grinding sequence.
Drill Bit Sharpener
Points and Wheels
Size: various
Material: aluminium oxide
Use: to grind metal
These small grindstones are mounted on a steel shaft that fits directly into the chuck of a portable electric drill or into the flexible drive. There are three kinds of shape; point, wheel, and ball, and they are used to open up holes and slots, round of edges, grind grooves and so on.
Points and Wheels
Oilstone
Size: (150mm x 37mm x 12mm); (200mm x 50mm x 25mm)
Material: natural stone, aluminum oxide, silicon carbide
Use: to sharpen tools
Oilstones are rectangular blocks of natural man-made stone, used to grind tool blades to a sharp edge. Stones are made with coarse, medium, or fine grit, or with a different grit on each side. For the home workshop, a combination stone with medium grit on one side to remove the metal quickly and a fine grit on the other to put the final edge on a blade would be ideal.
When the surface of a stone wears, regrind it as shown below. The surface itself may become clogged with oil, dust, and metal particles which prevent it from cutting efficiently. Scrub the surface with paraffin using a stiff bristle brush.
Oilstone
Brushing the Oilstone
Honing Guide
Size: to make blades 3mm to 59mm wide
Material: body- (steel), angle gauge/rollers- (nylon)
Use: to hold the blades at the correct sharpening angle
A blade should be sharpened at a constant angle to prevent it from being ground with a rounded edge. Although with practice this can be done by hand, it is quite difficult when sharpening spokeshaves and small blades from plough and combination planes. The honing guide makes it easy.
Honing Guide
Slipstones
Size: 100mm to 150mm
Material: natural stone, silicon carbide, aluminum oxide
Use: to sharpen irregular shaped tools such as gouges
Slipstones, like oilstones, are used to put the final sharp edge on cutting tools, but in this case, they are applied to the tool instead of the other way around. They are shaped to fit more irregular cutting edges, such as various gouges and parting tools, and machine cutters. The most common shapes are triangular, square, round, rectangular, and tapered.
Keep slipstones or oilstones in a box or well wrapped in cloth or newspaper to protect them from dirt and damage.
Slipstones
Common Slipstones
Scythe Stone
Size: (231mm to 300mm)
Material: natural stone, silicon carbide, aluminium oxide
Use: to sharpen scythes and sickles
Scythes are sharpened with long-shaped stones which are either flat tapered, ground tapered, or oval in section. Stand the scythe on the point of its blade. lubricate the scythe stone with oil or water and hone the scythe edge by stroking the blade from the end nearest the staff.
Sharpen both sides of the blade, finally holding the blade horizontally to hone the last few centimeters nearest the point. Keep the stone flat on the blade or the scythe's edge may become rounded over.
Scythe Stone
Hand Stone
Size: Diameter- (100mm)
Material: silicon carbide
Use: to sharpen axe blades
Once an axe has been ground on a grindstone, the edge is honed with a hand stone. Hold the stone in the palm of the hand with the fingers gripping the groove which protects them from the blade edge.
Hand Stone
Honing an Axe with a Hand Stone
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
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