What good is MSE anyway?
Delrin is a low-friction plastic that is extremely machineable; Delrin parts can be made on a laser cutter or mill. For small, precise parts, the Othermill is a great way to machine Delrin. Delrin is fairly strong, although it will deform substantially under higher loads.
Acrylic (in the form that Jacobs Hall sells) is a fairly brittle material that we recommend avoiding for use in flight parts. Acrylic is occaisionally useful for enclosures or signs. Polycarbonate is recommended as a substitute for acrylic unless the material must be laser cut.
This is the material we are currently using for our thrust chamber. Otherwise, generally avoid brass as there are better and cheaper substitutes available (usually aluminum).
Jacobs Hall sells plywood in several sizes and thicknesses for laser cutting. Common thicknesses are 0.25 in and 0.125 in. It is important to note that wood is anisotropic; its material properties vary significantly according to the direction of the forces applied. Wood can be used for structural parts, but it may be better to consider Lexan and aluminum first. Jacobs plywood is often used to make non-structural jigs, holders, etc.
Lexan is extremely strong, although it will flex slightly under load. Most of our Lexan parts are produced with a waterjet cutter, although they can be milled, bored, etc. afterward if needed. We are unable to cut Lexan with lasers; if laser cutting is desired and strength is not a priority, consider using Delrin instead.
PLA is a bio-based plastic commonly used for 3D printing. It is slightly more brittle than ABS, but it can absorb more energy before failure. See the "Acrylonitrile Butadiene Styrene (ABS)" entry for a comparison of PLA with ABS. It is also more readily available than any other 3D printing materials in the Jacobs Hall Makerspace. PLA is a good candidate for parts with complex geometry that are non-structural in nature. It is important to note that printed parts, like wood, are anisotropic; they fail much more easily in some directions (along layer lines) than others.
ESRA guidelines say we pretty much can't use stainless steel for anything important. That being said, other projects or non-critical parts might be allowed to use stainless steel; check the regulations! Many low-strength fasteners are made out of 18-8 stainless.