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window Plastic is a malleable and versatile material for construction at the scale we will be working in this class. It cuts as easily as wood most of the time and is as machinable as aluminum. It is non conductive and lightweight. Acrylic: This strong, stable material has excellent optical clarity and good tensile strength. Acrylics are generally very weather resistant. For this reason they are often used in windows, lab fixtures, and outdoor signs. Thin sheets cut easily with a matte knife. Polycarbonate: Most polycarbonates are very strong and have excellent optical clarity. Clear polycarbonates have glass-like clarity but have 10 times the impact strength of any other clear plastic. They are used in many window applications, as well as safety face shields and outdoor signs. Also known by the tradenames Lexan, Hyzod, and Tuffak. Nylon: Nylons typically resist chemical corrosion and have a slippery surface. Cast nylons are lightweight but can resist considerable wear. Common applications include pulleys, wear pads, and hydraulic systems. Acetal: These rigid materials have a slippery surface and withstand wear well. Common applications include valve components, gears, and bearings. Also known as Delrin. PVC: These materials are excellent electrical insulators with good impact strength. PVC plastics also resist chemical corrosion well. Applications include chemical processing, food applications, and waste treatment. Cutting - Soft plastics may be cut with a utility knife. Before you cut place a sheet of cardboard or another material on the table. We dont'want to cut into the table surface. Make sure to use a carpenters square or a metal rule to make sure you get a straight line. Thin harder plastics below an 1/8" can also be cut with a utiliy knife. Use a square and rule to ensure a straight line. You will also need to use clamps to hold down the rule. Keep the protective peel on your plastic when cutting. Thicker plastic will have to be cut using a saw like the band saw or a hacksaw. A special blade is required by some tools to cut plastic. Check before you proceed. You cut plastic on the band saw at a slower rate than wood. Forcing the plastic or using a dull blade heats the plastic causing it to deform and melt. If you use a hacksaw or coping saw you will need to use a fine blade. Make sure the blade is rated for plastic. Drilling - You will want to leave the proctective layer in the plastic when you are drilling. You may use wood bits to drill plastic. Try to avoid using higher end metal bits. If you work woth a lot of plastic it may be wise to purchase a plastic bit. When drilling always use a wood backing block so the drill can follow into it. Without the wood the plastic will most likely crack. When drilling holes over 1/4" you should always drill a smaller hole first, or pilot hole. Fastening - Of course you can use nuts and bolts to put your plastic together but there are other options as well. Threading - Some thicker plastics will allow you to run threads into them, meaning you can fasten straight to the material. More on threading in the metal section. Glue - It is possible in many cases to use a cement or glue to bind you plastic together. Know your plastic though. Most plastics require special cememts. Acrylic - to itself - acylic solvent - other plastic - epoxy - metal - contact cemet PVC - to itself - pvc to pvc solvent - other plastic - pvc to ? solvent- metal - contact cemet Common Types - Sheet Round Hollow Tube Angle Channel Resources - Small Parts McMaster - Plastic Types Explained and Sample Packs Industrial Plastics - Canal Street Wood is the most accessable material out there. Ranging from plywood to planking and dowels. Plywood - Most commonly available at shop grade, the kind with all the knot holes. Not practical for our uses. Other than shop grade wood is rated by letters. A being best down to C. On the preffered side we have A-A. But usually A-C ply is more available. For most of our uses we will be using 1/4" or 1/2" ply. Planking - Hardwood. Rather than using 1/4 ply you should look into planking. Available at the art supply store but a little more pricey, planking makes up for its price by giving you a flat and strong piece of wood. Use ash or birch. Most hardwoods come in small pieces, ususally 12 to 15 inches, Ideal for our scale of work. Look out for warped or bowed pieces when investing in this higher end wood. Dowels - Wood dowels, round wood rods, come in diameters from 1/16"to 1 1/2". Usually about three or four feet in diameter. Great and versitile piece of material. Cutting - Metal Aluminum - Aluminum alloys are strong, naturally soft, lightweight, ductile and malleable. They are easy to machine, fabricate, join and work. Aluminum is non-toxic and electrically and thermally conductive. Steel - Steel is iron that has been combined with other elements such as carbon, manganese and silicon. It falls into one of two families: carbon steel or alloy steel. Carbon steels are basic steels which harden only with surface (case) treatments. Alloy steels contain added elements that cause the steel to exhibit enhanced properties when heat treated. Stainless Steel - Stainless steels are alloys of iron to which at least 10% chromium has been added to impart corrosion resistance. A 10% chromium steel will not rust when exposed to weather. To obtain greater corrosion resistance, more nickel and chromium are added to the alloy. Along with iron and chromium, all stainless steels contain some carbon. The carbon is added for the same purpose as in ordinary steels- to make steel stronger. Other alloying elements are added for improved corrosion resistance, fabricability and variations in strength. These elements include nickel, molybdenum, copper, titanium, silicone, aluminum, sulfur and many others. Copper - Copper is corrosion resistant and highly ductile. Great for electrical applications. Brass- Brass resists atmospheric corrosion, water, and many salt water solutions. A high percentage of zinc makes it stronger and more durable than copper and bronze. It is easy to manufacture and maintains higher electrical characteristics. Nickel - Nickel features outstanding oxidation and chemical resistance. Commonly used in chemical processing, marine components and heat exchangers. Includes Monel, Inconel, and Hastelloy alloys and mu-metal foils. Tin - Tin is inherently soft and is readily alloyed with lead, antimony, silver, copper and other metals to form solder and babbitt materials. Cutting - Our horizontal bandsaw is set to cut metal, wood and plastic. The trick with all material will be feed rate. Metal should be fed slower than wood. Of course feed speed will depend on the thickness of the material that you are cutting. All metals when being machined will require you to use cutting fuid. If you are cutting steel you will use a different fluid than when cutting aluminum. Drilling - Use metal bits when cutting metal. Do not mix the wood bits with the metal bits. Metal bits need fluid which fight friction. If you get sawdust into the metal or machining process you will make your work harder for yourself. Fastening - You can use machine screws for thinner fastening and for thicker material you may want to cut your own threads. Cutting your own threads requires taps and dies. Common Types - Sheets Round Rod Tube Angle Channel Resources - Small Parts McMaster |