Maple syrup is made by putting taps into maple trees and letting the sap drip out into buckets or pipes. Because the sap is mostly water, it needs to be boiled down in order to create maple syrup--maple sap with most of the water removed. The boiling is done in an evaporator, also called an arch. Arches can take any number of forms, as long as they create a heat source underneath a container of sap in order to boil off the water.
One common method that is used for backyard operations is to cut a 55-gallon drum in half vertically, lay one half on its side and put legs on it. A fire is built in this drum and a large pan full of sap is placed on top of it. In order to improve the air flow, a chimney should be attached to one end of the drum and run up into the air at least 6 or 7 feet.
Many people build sugaring arches by welding together sheets of heavy steel. Evaporating pans can also be made by hand but are usually bought commercially. These pans are made in sizes up to 4 or 5 feet across and 10 feet long. The arch can be built to accommodate the size of the pan. As with the smaller arch, a chimney needs to be run out of one end. Ideally, the setup will be in an open area with trees around; guy wires can then be strung from the chimney to the trees for stabilization.
Whatever the size of the pan, the the bottom must be flat and as level as possible. If it isn't, when the syrup boils down to a certain point, it will begin to burn in some sections before it is ready in others. To avoid this, many people take the nearly finished syrup off of the large arch and do the final boiling on a stove in a smaller pan. With the syrup more centralized and not as shallow, it can be finished with less risk of burning.
Nearly all homemade arches are heated with wood. There are larger systems that use oil, but these are not practical for the small operation. A good source of wood for an arch is offcuts from a mill. When mills cut lumber from logs, they create long, thin offcuts that are mostly bark and outer wood. These are good for arches because they are cheap and because they are long enough to poke into the fire under the arch and have them burn along the entire length of the pan, an important process for even boiling.
Many traditional sugaring operations have a small building built around the arch, called a sugar shack. Sugar shacks have distinctive roofs, with the center ridge lifted, creating a vent along the length of the building to let the steam out. Beginning in March, everyone knows when the sugaring season has begun by the clouds of steam coming from the sugar shacks.