Rules of thumb for set construction - TheatreFace

"Especially since we have no…

2012-08-01T04:20:28.488Z

"Especially since we have no storage space."

Ref: Shakespeare, William, "As you like it", Act II, Scene VII. That is because 'All the world is a stage'. Sad, but true, the first thing to go in a building footprint is the storage space. It is intangible to most people that someone might actually need someplace to keep the magic needed and produced in the cycle of teaching and show production. (Why not? If it 'magically' appears, then it can 'magically' disappear, too - Right?)

The result is junk piled on top of crud, on top of more junk; and all of it in front of an electrical panel or fire exit. The other evolution of storage space I frequently see is someone unfamiliar with the needs of a theatre plant commandeering the space for an unnecessary office or network server closet.

I would say that for a high s…

2012-07-31T15:56:30.361Z

I would say that for a high school setting, wood is the best way to go. The shows are so quick, that the time it takes to weld the fit things perfectly you can have a better product with wood, and most of the time, the kids can actually do the work. Right now, I would not trust a high schooler with welding equipment and I am not sure the school would appreciate it either. We needed a West Side story balcony that I Started to use steal, but by the time I analyzed the cost of everything it was going to cost a fortune. Wood held up and it was quick and easy to tear down. Especially since we have no storage space.

My main rule is Over build it…

2012-01-23T08:34:33.739Z

My main rule is Over build it. It can never be too safe, it will almost always be cheaper than having an actor get hurt.

As for Steel or wood, my rule is steel whenever possible; why, see the first rule

You know, this is a great que…

2011-06-09T16:43:11.308Z

You know, this is a great question that made me stop and think about why I gravitated towards steel for some pieces and wood for others. In short, I think there are three things that drove my decisions. Design, strength of the piece, and work flow in the shop.

Design. Did the designer design a structure that would be to bulky if made from wood. A bridge that had a long span but a thin (relatively) profile, or a circular staircasefor instance. Some things just screamed, "build me out of steel."

Strength. As many have already said in this posting, the question to be answered is, "does the scenic piece need to have the strength that steel provides?"

Work flow. One of the considerations that I took into account was how busy the shop was, and how far behind were we in the build. There were pieces that I might have wanted to build out of steel, but couldn't because to do so would overload the metal shop and bog down the shop process as a whole. If there are and scenic artists watching this post, you know how it feels to see the days tick by while you are not able to get your hands on the scenery and get it painted.

If you are fortunate to have a workforce who are all well versed in working in steel, this is less of a problem. However, steel can make some processes take longer, and you may simply not have the luxury of time to build it all out of steel. But workforce is only consideration. I always had more wood working tools than steel working tools in my shops, so I could make better use of my workforce by always keeping an eye on whether or not I was overloading on area of the shop, while under-utilizing another part.

In the end, I do not think I had any hard and fast rules. Each show, and each piece of scenery, created the constraints that helped me determine what tools and techniques to use.

thank you Rich, you beat me t…

2011-01-21T02:57:12.709Z

thank you Rich, you beat me to the punch. my working idea currently is to compare a fixed load over a varying length and compare standard dressed lumber to standard steel sizes commonly used by theaters. I'm am interested in peoples thoughts on everything. ( I know that is broad, but it is discussions like this that I hope to garner enough information to proceed)

As the instructor that first…

2011-01-21T02:28:58.165Z

As the instructor that first piqued Ian's interest in this question, I'd love to provide a bit more context. In a structural analysis course, we were comparing 2x4 #2 spruce-pine-fir with 1x2x16ga MT1010 steel and their ability to carry a uniformly-distributed load, simply supported across 8' (used the algebraic approximations found in the National Design Specification for sawn lumber and the Steel Construction Manual). In this situation, a 2x4 is stronger (albeit only marginally) and can carry a slightly larger evenly-distributed load before showing appreciable deflection.

After discovering this, everyone in class asked, "Why built it with steel?" This sparked a discussion about the merits of structural members beyond simply their ability to support a load; for example, connection points drilled into a steel member will not show nearly the wear that holes in wood members will display in the same amount of time, and, as Tim mentions, the steel-members are longer-lasting, though harder to secure with fasteners. The upshot of this conversation was that some shops and theatres tend to rely on habits, practices, and rules of thumb that sometimes are not the most appropriate. (For example, ye-old 2x4-framed 4'x8' platform is a relatively inefficient use of storage space, material, and (lifting) labor--but they're still fairly common.)

I'm guessing, Ian, that's what you're asking about, yes?

A key element in the selectio…

2011-01-20T23:33:52.966Z

A key element in the selection of materials should be the quantifiable structural strength properties they possess. Set pieces that will carry the weight of performers and/or crew must be strong enough to safely support the live loads imposed upon them. This involves both the bracing and flat materials as well as the fasteners that hold them together. A solid steel bar supported by a ¼” wooden dowel is just about as useless as an oak beam supported by a #6 sheet-rock screw.

Platforms, ladders, stairs, and other creations that carry live loads must be designed to meet relevant building codes regardless of the length of time they will be in use. Unlike a dropped potato chip with a ‘five-second rule’, a structure must carry the expected working load regardless of its time in-service be it a five minute vignette or a five year Broadway run.

If weight is a concern, then consider lightweight materials of appropriate strength. Aluminum or fiberglass beams in lieu of 2x4’s, space frames in lieu of post & beam structures, and aluminum tubing and SpeedRail fittings in lieu of the more conventional 1½ schedule 40 steel pipe. Fasteners can be lightweight, too. High strength aluminum and titanium bolts are available and for mission-critical objects that must be lightweight they can provide significant holding power.

Structural adhesives can be very useful, too, but be sure to live-load sand-bag test the final results before climbing on them or hanging from them. Be sure to check them regularly for de-lamination failures, just as you would check metal for fatigue cracks and wood for splitting and cracking.

Bolted joints can be as strong as welded joints and do not require the welding skills of steel and aluminum. They also offer the benefit of disassembly after the set-piece is out of service. Become familiar with the SAE and ASTM fastener (nut, bolt, & washer) strength grading systems and how they are represented on the components. Using a hardware store pot-metal nut on a Grade 8 Bolt does not make a Grade 8 rated assembly. It is also important to understand the difference between the axial loading strength of a bolted connection vs. the shear loading strength. Wood screws have very little axial loading strength (they are mostly 'nails with tread'), and typically not very good shear strength, either (the wood can sometimes split before the screw bends or breaks).

With a coat of paint, any material can be made to look like any other material (well, except maybe clear items). Another point to be considered is that all materials used for scenery must be treated with fire retardants or be inherently incombustible (Ref: NFPA Life Safety Code 101, Sections 12.4.5.11). The cost of intumescent paint must be added to the cost of wood and plastic materials, where metal structural elements can remain untreated.

Lastly, the cost of recycling the materials should be considered. Wood and plastic typically just goes to the dump (sadly, no one will buy your used wood, and used plastic is of extremely low value), where metal parts can typically be reused and / or recycled.

In summary, the 'rules' used should include the Building Code Rules (UBC, ANSI, NFPA, ADA, OSHA), sound Structural Engineering, and other well documented formulae that are well researched and documented.

For another viewpoint on set piece design see: http://www.theatreface.com/profiles/blogs/hard-floors-vs-hard-heads

Well said David.

2011-01-20T20:35:04.710Z

Well said David.

There is an old saying: "FAST…

2011-01-20T20:28:24.741Z

There is an old saying:

"FAST - CHEAP - GOOD, pick any 2"

If you go for fast and cheap you won't get a good result.

If you funds ae lacking but you want good, then it will probably take a while to pull it together.

If you need it in a hurry, but you need quality too, expect to spend serious money.

Here is one of the rules that I try to keep in the back of my head when I'm building anything.

Design in such a way that if you put all of the pieces together, gravity would hold it up with no fasteners or glue. Of course that doesn't account for lateral forces so you really do need fasteners (screws, staples, etc.). If you design with this in mind, then the fasteners are not supporting any weight, they just keep the piece from falling apart.

I know that most of us are still using drywall screws even though their shear strength is so hot. That is why you can grab a stripped screw with a pair of pliers and break it right off. If you can design with the above concept in mind, the screws won't have to support any shear load.

If you are building cheap, fast, and dirty, 2"x 4"s will often get the job done. They are very forgiving. However, if you are a craftsman and you are building pieces that will be around for years and you want to be proud of what you built, a flat of step unit built out construction grade 2"x 4"s or strapping doesn't cut it. However you don't get cheap and fast if you want a quality piece.

Cost + purpose + length of us…

2011-01-20T19:35:15.659Z

Cost + purpose + length of use, are some of the factors I use in determining what to use. Wood is good to use for basic construction. Steel works well in situations where you need support and strength. Steel platforms will last longer an are not as thick and easier to store but more expensive to make. Wood goes together faster then steel and you don't need a skilled welder. There are a lot of factors that go into the decision but, in the end it really just comes down to what will work best to do what you need.