The most widely used tool for marking right-angles on wood is the try-square. For marking other angles, a sliding bevel or mitre square can be used. The sliding bevel can be adjusted to any angle -including a right-angle; the mitre square is fixed at 45 degrees. A combination square can be used to mark right-angles and 45 degree angles. All these tools can be used for checking angles and corners.
Try-square
This is a tool for marking right-angles and checking their accuracy. The traditional try-square has a steel blade and a wood stock - usually ebony, beech or rosewood with a brass edging strip. Nowadays, many try-squares have plastic stocks these are a better choice if the try-square is likely to be used and left in damp conditions. Many different sizes are available varying from around 100mm to 300mm. Before using a try-square, test its squareness by holding the stock against a straight-edge and marking a line on it. Reverse the blade, hold the other edge of the stock firmly against the straight-edge and check that the edge of the blade coincides exactly with the line marked. Any error in squareness is doubled and should be fairly easy to sec.
When using a try-square for marking a right-angle, make sure that the stock is held firmly against the face side or face edge. When checking squareness, hold the wood up to the light with the try-square firmly against the face side. Light coming under the blade will show up any unevenness.
Square template
This is a useful device for marking wood which you want to cut through. It is basically an elongated L-shaped piece of wood or steel about 150mm long. When a piece of wood is put in the L, two adjacent sides can be marked.
Squaring rod
It is almost impossible to check the squareness of a large rectangular framework - the framework for a built-in wardrobe, say accurately with a try-square. To do this you need a squaring rod - a length of wood with one end sharpened to a chisel edge. To square a framework, the chisel edge should be pushed into one corner of the frame with the squaring rod held across the diagonal and the opposite corner should be marked on the rod. The rod should then be placed across the other diagonal and the framework adjusted until both diagonals are equal.
Sliding bevel
This has a steel blade passing through the end of a stock of ebony, beech or rosewood. The steel blade has a slot cut along half its length which allows it to slide through the stock and to be locked at any required angle. To mark a particular angle, the blade angle should be adjusted with a protractor. A sliding bevel can be used for marking dovetail joints.
Mitre template (or block)
This can be used for making mitres across small pieces of wood for picture framing, say. It is often made of beech or boxwood, about 100mm to 150mm long and L-shaped. It usually has two slots at 45 degrees and one at 90 degrees. You hold the wood in the crook of the 'L' and use one of the slots to guide your saw. Because the slots do not come down to the bottom, the workpiece has to be supported on a piece of scrap wood.
Mitre box
This is similar to a mitre block but U-shaped. It usually has two sets of 45-degree slots but rarely a 90-degree one. An advantage is that the saw is guided on both sides of the wood. Good quality mitre boxes have protective metal guides fitted over the slots. For serious mitre cutting (if you are framing a number of pictures, say) a mitre cutting machine, with its own saw, would be useful.
Combination square
This can be used for marking right-angles, checking internal and external right-angles and marking 45-degree mitres. It is more versatile than a try-square but it is also more cumbersome to use. The metal stock generally has a built-in spirit level and removable scribing pin. A combination square can also be used as a depth gauge for mortises.
| Price : Too low to display | Post Date : Dec 26, 2011 14:36:22
