Squares are important tools for setting accurate measurements and cuts for wood and metal, as well as for checking the square fit of glued joins and frames. For scale models and miniatures, where being off square can destroy a fine tolerance construction, squares are also essential for ensuring tool faces, blades, fences and sanding blocks are accurately square. Smaller, highly engineered, machinists' squares are often easiest to use with scale models as well as ideal for setting up machines. A narrow ruled combination square with a metal head is also useful. Prices range from under $10 up. Avoid plastic tools.
Milled to exact tolerances making them the most accurate of squares, these steel tools have a thickened stock and a thinner blade which joins the stock at a perfect right angle. The Engineer's square is used to true blades, fences and attachments on machines, and to check that tool faces and carpenters joins are square. The stock can be held against wood or metal and the blade used as a marking guideline. The engineer's square usually has a small notch in the stock at the join of the stock and the blade to accommodate small burs on the edge face of tools being sharpened. Engineer's squares are a good size for model work. Thin blade engineers squares are available designed with thinner stocks for marking thinner materials more easily.
The carpenter's try square is similar to a machinist's square although the stock is generally made from rosewood with a brass facing on the inside edge for accuracy and the blade usually has marked measurement guides useful for measuring miters and lines for joins. Carpenter's squares are usually larger than machinist's squares and so are less useful for miniaturists working with smaller models. The carpenter's square is not considered to be as accurate as a machinist's square, as the materials it is made from are more susceptible to bending and wear. It is useful for marking, but not for setting a true square on saws and other tools. Try squares are available with blades from 3 – 15 inches long.
This square has a steel ruler with several different heads that slide along it and can be set along the ruler. It is most often found with a squaring head (measuring 45 and 90 degree angles), but protractor heads which measure specific angles from 1 to 180 degrees and centering heads which allow center marking of materials are also found. Most combination squares contain small levels and can be used to check for level and plumb. They are useful for transferring duplicate measurements where one depth is set up on the ruler and transferred to all pieces of an assembly. If the ruler is thin enough it is also useful for measuring the depth of any notch the ruler will fit into, as well as for measuring level, height, and miter angles.
The Framing Square or Steel Square is a flat right angled steel ruler with measurements on both sides but no thickened stock. The framing square is much less likely to be at a true right angle and is primarily used for marking framing measurements for construction purposes. It is usually not accurate enough to set up power tool tolerances. Framing squares are available in smaller sizes (3 x 4 inch) which are more useful for modellers than the normal 16 x 24 inch framing square.