Old carpenter's rule
I have LOTS of rulers, and I use almost all of them regularly. It's amazing how many different ones are "out there" and how each fulfills a unique need in my woodworking and miniatures. Below is an assortment of them I gathered up from my work room and toolkits. I thought that if you're trying to figure out what tools you might need for this hobby, then this could be useful to you (or if you're experienced, you may feel it's worth sharing with someone who is new to the hobby).The largest ruler (#1 above) probably gets the least amount of my use. However, when I was preparing to cut out large pieces of plywood to build Sara's dollhouse, this ruler, which serves as a four foot wide T-square, was a very useful tool. I also use it occasionally when I need to cut a wide piece of matte board.
The smaller T-square, #12 on the right of the picture, hangs at the ready in my workshop. I use it for drawing and for cutting dollhouse wallpaper or fabric in exactly square dimensions. The easiest way to use this T-Square for cutting is to lay one edge of the fabric or the wallpaper along the straight side of a cutting mat. Set the T-square down on top of the fabric or paper with the plastic T placed against the edge of the mat.
Your ruler is now perfectly set at a right angle to make a cut. All you have to do is move the T-square to whatever width you need, and slice along the ruler. (Hint: Being a right-handed person, I press down with the fingers on my left hand about midway down the length of the ruler to hold it firmly in place and slice on the right side of the T-square with my roller cutter or Xacto knife.)
The "ruler" marked #2 above is a matte cutting guide, which also has a ruler along its edge. This is an especially safe tool for guiding your knife cuts on matte board, which requires either multiple strokes with your Xacto knife or heavy pressure on the knife.
When cutting matte board, it's easy for the knife to slip up over the edge of a thin ruler, putting your fingers in great jeopardy of getting cut. This special ruler has a center ridge that sticks up almost an inch and goes down the entire length of the ruler. I can use this ridge to pick up and adjust it by purhins or pulling on that ridge. Once the ruler is exactly where I need it, I can put my hands behind the ridge, and they are safely protected from the knife blade slipping over the edge of the ruler and toward my very tender pinkies.
The carpenter's ruler (#3), is a terrific tool for measuring inside distances within dollhouse or roombox rooms. It has a brass slide-out piece that can give you an exact measurement of the room's length. I like it even better than a standard tape measure (#5) for doing inside room measurements. That's because once you've slid out the brass extender to measure a room, it holds the measurement. (It does require a little math, though, since the brass insert measurement has to be added to the length of the yellow fold-out part of the ruler to get the complete measurement length.
Tape measures (#5) are designed to accommodate for inside and outside measuring by incorporating a little play in the steel tip. So, when I remove it from doing an inside measurement, and then try to place it onto a piece of trim molding and do an outside measurement, I can get myself quite confused. The carpenter ruler eliminates that problem. That's why I always use the carpenter ruler now for measuring my dollhouse rooms.
The problem with a carpenter rule, though, is its big. It folds up to a length of just under eight inches. When you're trying to measure doorways or windows, it can get awkward trying to fit this tool into tight spaces to get an accurate measure. That's where the mechanic's ruler (#10) comes into play!
I use the little mechanics' ruler a LOT. It has a scale on one side that goes down to 64ths of an inch and 32nds of an inch on the other. PLUS on the back, the ruler has a list of digital equivalents to the ten thousandths of an inch starting at 1/64 and going up to 63/64. It has a pocket clip affixed to it so you can clip it to a shirt pocket. That "clip" also can be turned so that you can measure inside dimensions of a window. I consider this a must-have ruler for an active miniaturist!
The two rulers marked #6 are both clear plastic, centering rulers. One of our club members introduced me to this kind of ruler. It has a zero in the middle, and then counts out inch by inch in both directions to the ends of the ruler, and it also starts with zero on opposite ends and goes to 12 inches. Set the ruler down on something and in short order, you can find the center of an object. When you need to find the center of a piece of fabric or a center point on a railing, this tool works great!
I use the white, triangle-shaped ruler (#7) for doing scale drawings. With its soft plastic body, it is NOT a tool to use for any knife cutting. It has a wide range of scales, dividing the inches into six different scales. It's useful for helping me to "draw" room plans on my computer, because it has a 1/10 scale on one of its sides. Since PowerPoint allows me to "move" and size objects using decimals of an inch, this ruler is a good tool. It also has a 1:6 scale, which can be used for 1/12 scale work, if you're imaginative. This one is NOT a critical ruler to use/have, though.
I use a caliper when I need some precise accuracy. I like it especially for setting up a cutting width on my miniature table saw. A caliper can measure both inside dimensions as well as outside dimensions. My wife gave me the digital caliper, and I must say, it's SO much easier to use than a vernier caliper! The jaws of the caliper can be set to slide a little stiffly; thus, like the carpenter's ruler, once you've tightened the caliper down on the wood you're measuring, you can slide it off of the object and this ruler stays open to the exact width you need.
The ruler at left is sometimes called a try square (it's number 9 in the top photo). Depending on the manufacturer, I've also found references to it as being called a tri-square, a combination square or an adjustable square. The one pictured here is a small, 4" long "adjustable double square." It costs about $10 from MicroMark. The ruler itself slides in the black metal handle, which allows me to make accurate measurements of depth. It's also machined so that it is precisely a 90 degree right angle.
You can buy a miniature square, or you can buy a full-scale, combination square for just a little more money - around $15. They are one foot long, and handy as all get out for little OR bigger projects around the home. You can buy this kind of adjustable square at virtually any hardware store that sells tools. If you're just starting out, and don't have any tools, buy a combination square ruler. The hardware store version even includes a level in the handle so you can adjust pictures on your walls!
I hope the photo below helps you see another key way I have used this square. I found that most of the miniature miter boxes are designed for cutting pieces of small, wood trim. So, when I was building my fancy Victorian bookcase, and wanted a precisely cut piece of cherry wood I couldn't pop a four-inch wide piece of wood into my miterbox and cut off a length of the wood.
When I built the bookcase, I also didn't have a good quality, miniaturists table saw. So, I put a piece of plywood down on my work space, set the cherry wood on top of that, and then pushed the black part of the square against both the plywood and the cherry wood. This lined up the edge of both the plywood and the cherry wood with the fat base of the ruler. I then carefully tightened a C-clamp down onto the ruler blade of the square. With the clamp holding everything perfectly square, I was able to set a razor saw flush against the ruler edge. This process produced all of the larger square pieces of that bookshelf, and it turned out wonderfully! So, if you're serious about making dollhouses and miniature wood projects, get thee to a hardware store if you don't have a combination square!