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Platforming, things to stand on, stage decks, etc.

Styrofoam

Buildingfacade

A relatively popular use of Styrofoam is to carve out intricate patterns and then apply the sheets of Styrofoam to walls and other flats. There are many methods of carving out Styrofoam, the simplest being with a utility knife. Extreme caution must be taken when using sharp tools, etc. Another handy tool is a standard kitchen electric knife; though these are more popularly used for carving regular foam rubber versus Styrofoam.

hw-sled

Custom cutting tools are also available for cutting Styrofoam. 

As you can see by the pattern of the cutting wire, this is being used to cut out crown molding. Using hotwire cutting tools are extremely efficient when cutting Styrofoam, but bring additional safety precautions to the table. First, they are very hot! Second, but more importantly, they must be used in well ventilated areas and may require wearing safety masks with specialized air filters. You’ll need to refer to the material data safety sheets as needed. http://www.hotwiredirect.com/products/hot-knife/

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Platforming, things to stand on, stage decks, etc.

Platforming Article #6

It may seem that I am making such a strong point for stud walls that they are the best way to leg platforms. While stud walls are indeed one of my favorite methods, they are far from the only one I use. There are conditions where stud walls are a poor choice. For example, In the layout shown in the next illustration, bolt on legs or parallel frames would be the most efficient for heights 2″ or less. In general, if your overall platform height is 2″ or less, stud walls are less likely to be time, material or cost efficient. Even at this low height, stud walls are still the best in overall weight bearing and weight transfer capability of all wood, shop built platform support systems. Each and every situation has it’s own solution for “best”. Best is the solution that fits your budget in terms of both materials and labor, fits your crew in terms of skills and time to build and works with your theatre in terms of storage, use and reuse.

One of the advantages of the stud wall system is the way it works in areas that are larger than single platforms. The following illustrations show you a 16″ x 12″ deck made up of 4×8 platforms. The first illustration shows the number and layout of legs for that deck. The rest show possible stud wall layouts for the same deck.

It is easy to see that a small number of stud walls can replace a large number of legs. At first glance, it appears that the stud wall method requires more lumber and more individual boards and thus more time to build. However, stud wall legging greatly reduces the amount of diagonal bracing needed. This translates into more “legs/studs” but less cross bracing and tends to equalize the lumber needed. The simplicity of the construction requires fewer construction steps and results in a very fast construction method. If the deck is to be moved stored or toured, it comes apart in very few pieces and packs flat in a truck or storage area.

Variations on the stud wall can be seen in tiered levels and rakes or ramps. In these platform setups, stud walls can be shaped to fit the stair step shape.

Ramp or rakes are the other half of odd shaped stud walls. Earlier I mentioned that it is rarely efficient in labor or materials to build stud walls for platforms less than two feet high. The exception is when a ramp slopes down to the floor. The ease of making a smooth, even slope is well justified. When you lay out the top and bottom plate on the shop floor, the angle and length of the studs can be marked off directly without measuring, math or trig. If you cut a stud a bit too long or too short, simply move it a fraction of an inch one way or the other until it fits between the top and bottom plate. Elegant? No! Effective, quick, strong and workable? You bet! Two Simple examples of sloped studwall support are shown below.

So far, we have looked a number of ways to use studwalls to support platforms. Next month we will examine some ways that stud walls can be used for more than just to support a deck, such as to bridge openings, support over hangs and other uses. We will also look into how to fasten platforms and decks to the stud walls.

For now, have a happy holiday season, don’t sweat the small stuff, and remember, Its ALL small stuff!

Michael Power

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Platforming, things to stand on, stage decks, etc.

Platforming Article #5

The standard leg uses friction as a major element of support. If you have ever seen a magician or “box-juggler” perform a juggling act with three or more cigar boxes (or similar size/shape cardboard boxes) tossing them into the air and catching them between other boxes, you have seen the friction part of the puzzle. If you have ever used a “C” clamp to fasten a temporary leg to a platform or to support a piece of work in the shop you have used this principle. The method of fastening the leg to the platform can add to the friction element. Bolts with nuts add the greatest amount of friction force, screws or lag screws a moderate amount and nails or pneumatic staples, the least.

The other half of the equation in the standard leg is the shear strength of the various fasteners. When the leg is fastened to the platform frame, there is a shearing action formed, much like the shearing action performed by common sewing scissors.

The shear strength of the fastener added to the friction force is the total strength of the “standard” type of leg. It should be obvious by now that fasteners which produce a compressive force will be stronger than those that do not. All fasteners produce some degree of compressive force, smooth shank nails the least, bolts and nuts the most, with screws, staples and ring shank nails falling in the middle.

What may not be obvious is that more fasteners do not necessarily mean a stronger joint. If wood is the construction material and a leg is between 2 ½” and 3 ½” wide and a platform frame is between 3 ½” and 5 ½” wide, there are a limited number of fasteners that can be inserted in any joint. At some point the grain of the wood will split or there are so many holes made for bolts that there is no wood left. What is the “right” number of fasteners, is there a specific pattern that is stronger? With nails, screws or staples, the maximum number is 8 if both leg and frame are nominal 6″ wide. With bolts, the maximum is 5. If either member is less than 6″ nominal wide the maximum number drops.

Any additional fasteners than shown above will either add so little extra strength as to be useless or they will actually start to weaken the joint.

The most common standard leg is the ordinary 2×4. It is cheap, strong and easy. Other standard legs are single piece legs made of 2×6, or 4×4. Manufactured legs, those made of more than a single piece of lumber, are almost always made in an “L” section. Other variations are the box tube and the “T” section. “L” section legs are the most structurally sound in terms of weight versus strength. The box leg is used where the bulk look is desired but weight is a factor. The “T” section leg is used when light weight is needed and for design reasons the “T” shape is either visible and more desirable or the bracing is easier to attach.

While wood is not the only material used for standard legs, it is the most common. Steel is also used as a standard leg. Square or rectangular steel tube is the most common form of steel leg. Other forms are angle iron, slotted angle iron, Tele-spar, Uni-strut and pipe.

These are all fastened to the inside of the platform frame just as other “standard” legs. While through bolts are the most common form of fastening steel legs to platforms, screws and nails through predrilled holes are another method. One last method of fastening steel legs to platforms is by pneumatic “T” nails. These are specially hardened nails that can penetrate 16-gauge steel tube. Personally I only recommend through bolts to attach steel legs.

The second type of leg is the compression leg. It is called that because the actual support of the leg is in direct compression under the frame. If 100% of the force was straight down and there was absolutely no sideways force, a compression leg would support the load with out any fasteners or bracing actually connecting it to the platform. Of course we all know that the entropy of the entire universe would have to come to a halt for that degree of stillness to exist for more than a very brief moment. Once the leg is braced and secured to other legs, gravity can become the only actual attachment between the legs and the platform. The parallel platform is an example of this as are several commercially built platform systems.

The most common compression leg is the one shown above, a 2 x 4 leg with a ¾ ply cleat attached. For strength in attachment to the platform, the cleat needs to be only 10 ½” long, or about 3 times the width of the platform frame and the same width as the leg. However the best practice is to continue the cleat flush to the bottom of the leg. This allows bracing and stiffeners on the inside of the legs to all follow the same plane. In addition the full-length cleat adds a great deal of stiffness to the leg, especially over 30″ long. One variation of this leg is to use 2 x 6 as the leg but to keep the cleat only 3 ½” wide and flush to one side. This allows the leg to be placed at the corner of the platform and have the leg actually support both frame pieces at that corner.

Compression legs can also be used with platforms whose frames are one by stock or 5/4 stock, the leg material is simply the same thickness as the frame.

A very good variation on the compression leg is a combination of the “L” section leg and the common compression leg. The leg is made with “by six” stock for the leg, thickness to match the platform frames. The cleat section is also L” shaped. These legs provide a very stiff, strong leg that needs little or no cross bracing at 3″ tall or less.

All of the metal leg types can also be made in to compression legs. To make compression legs of metal requires welding corner brackets to hold the legs and support the platform frames. There many different methods of making the legs, some with a “universal” bracket that can be fitted with different lengths of legs to suit the show and others that have a permanent length of leg welded to each bracket. The brackets are all similar in that they have a flange that supports the frame and a face with predrilled holes for bolts or screws. The main difference between different types is whether the socket for the leg (or the leg itself) is welded on under the bracket or inside the predrilled faces.

The socket type of bracket can also be welded under the corner of the flange but then, if the bracket is left on the platform, it is permanently legged to the height dictated by the length of the socket.

The standard and compression legs cover a large number of the legging situations you will encounter, but by no means will they suit every situation.

The main advantages of the standard leg are:

It is the least expensive legging system for material costs on a one-time basis when using a simple leg such as a 2×4.

They are the quickest method unless you already have a large supply of legs of the desired height in stock, especially if you are using a simple leg such as a 2×4. This can also translate into additional $$ savings if your carpenters are paid by the hour.

Leg length is determined by the thickness of the platform lid, which tends to be very consistent compared to the width of framing members.

Requires the least amount of skill on the part of the carpenters.

The disadvantages are:

They tend to shorten the life of stock platforms by “chewing up” the corners with numerous bolt/screw holes.

They are not as strong as compression legs and are rarely suitable for heavy and/or prolonged dancing especially of the clog, tap or step styles.

The main advantages of the compression legs are:

They are far stronger and stiffer when properly braced.

They do not tear up the corners of stock platforms.

If they are built well, they can be used over and over again, more times than standard legs, which can result in a materials saving over time.

The disadvantages are:

They require greater skill and more time to construct.

The length of the leg is dependent on the width of the platform frame members which can vary from one lumber lot to the next even when purchased from the same lumber company. Not every stock platform is the same.

They require more storage space than standard legs.

As can be readily seen, there are many way of legging platforms and I have just touched on some of the major ways to do it. What is right for you depends on the skills of your workers and the tools you have available. It also depends on your budget both in terms of time and money. It can also depend on your available storage area, if you can’t store it, do you need to build it to last 20 years?

Next Month we will look at a method of supporting platforms that is very strong and stable but isn’t really “legs”. It is also very good for supporting raked or sloped stage sections. It is the “Stud Wall” method.

Until then, keep the green side up, don’t sweat the small stuff,.. and remember. It’s all small stuff!

Michael Powers

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Platforming, things to stand on, stage decks, etc.

Platforming Article #4

Before we describe specific legging systems we need to define just what a legging system does and how it does it. What is legging? Legging is: A system of raising a platform to a desired height, spaced to prevent sagging and with sufficient cross bracing to prevent lateral movement. The function of any legging system is to transfer the load on the platform to the structure it rests on, whether that is the permanent stage floor or other temporary stage platforming. To tell you just how legs and bracing perform that task will require some drawings, a brief explanation of the geometry of a triangles and the ability to multiply by 50.

First let’s look at the leg itself and that number 50 that I mentioned. Any leg will be very stiff in short lengths, but every leg will become flexible when it gets long enough. A piece of ¾” x ¾” pine will support 1,000 pounds when it is only one inch long. A 12″ steel I-beam will barely support it’s own weight at 100″ tall, a stiff wind will bend and collapse it. How tall or long can a leg be and be safe? A standard formula that works for theatrical use is a 50:1 ratio. That is 50 times the narrowest cross section of the leg is the maximum height that leg can be without some form of bracing to prevent buckling or bending. This formula will work for all materials used in general stagecraft, wood, steel tube, pipe etc. For example a simple 2″ x 4″ leg can be 45” tall before it needs bracing to prevent buckling or bending. The calculation is simple, the nominal 2″ thickness which equals 1 ½” times 50 equals 75″ or 6″-3″. If you nail two 1×4 boards together to form an “L” or “T” section, the narrowest dimension is 3 ½”. Fifty times 3 ½” equals 175″ or 14″-7″.

Now, this DOES NOT mean you can build a 6″tall platform with 2×4 legs or a 14″ tall platform with “L” legs and no cross bracing. The leg is actually fastened to the platform in a very small area and the length provides a very effective lever when the platform sways the least bit. Twenty pounds of sideways push will cause the 6″ platform to fold sideways and the legs to split or tear out the fasteners. It would only take about 5 pounds of sideways push to topple the 14″ unit.

Now it seems like I have contradicted myself. I said that you could build a platform with a leg 50 times taller than it is thick and then I tell you that it will collapse. The 50:1 leg will support the platform and the load, but only if the weight is completely still and there is no sideways motion caused by walking actors, dancers etc. Our next task is to brace the platform to stop any swaying or sideways motion and this is where the triangle comes into play. The triangle is the only geometric form that can not change its shape without breaking either a side or separating a joint.

Triangular bracing is what makes tall buildings, bridges, the Eiffel tower and other construction possible. Look at a bridge or a building under construction before the bricks and facing are added. What you see is a series of triangles in some form or after.

Categories
Platforming, things to stand on, stage decks, etc.

Platforming Article #3

All of us confront stress skin units everyday; the most common is the hollow core door. Other examples are plywood, steel I-beams in construction and many of the tabletops in folding business tables. If you do artwork or photo mounting you may have come across a product called foam core. All of these are examples of stress skin construction.

Now let’s look at the same units with a load applied.

The hollow core door has a very thin skin about 1/16″ to 1/8″ thick on each side. The outside frame between the skins is about 2″wide on the sides with 4″ extra in the doorknob position. The top and bottom frames are usually about 2″ wide. The interior of the door is usually filled with CARDBOARD! The cardboard is about 1/32″ thick and formed into a honeycomb with the cardboard on edge and each cell of the honeycomb is about 1″ to 1 ½” across. When the door is assembled, every edge of the honeycomb is covered with an adhesive; every edge and face of each component that comes in contact with another is coated with an adhesive. When the door is finished it is very stiff. Many of you have made drafting tables, shelves and benches with old doors. You may have noticed that even though the door can support a great deal of weight, it is lightweight and easy to handle. If you have ever lifted a solid core door, you know they are very heavy and awkward to handle.

To make a comparison that will be readily understood, a common stock platform, using 2×4 for the framing members and ¾” plywood for the lid, will sag noticeably with a 150 lb. weight in the center if it is supported only at the ends. A 4×8 stress skin unit with a 2×4 frame with 8″ members on 16″ centers and with a 5/8″ lid and a 3/8″ bottom will support almost 2,000 lbs. evenly distributed which is about 60 lbs. psf. or over 500 lbs. in the center before it deflects more than ¼”.

That is the essence of stress skin construction. A very high strength to weight ratio. In the construction industry, reduced weight usually means less materiel and less materiel means reduced manufacturing costs. In theatre the reduced weight means easier handling which can result in time savings or labor savings.

The Triscuit platform takes advantage of the stress skin principle to make a unit that is small enough and light enough for one person to handle yet is very strong. Because of its size and thickness, triscuits can be stored in smaller spaces. For comparison, four 4″x8″ stock platforms with a 2×4 frame, require a space 4″ x 8″ and 17″ deep. Eight triscuits (equal in floor area to the four 4×8 units) can be stored in a space 4″ x 4″ x 19″ deep, just an inch more than half the space.

Strong, light, store in less space, why don’t we all use triscuits? There are some drawbacks. First of all they take longer to build. Second they must be built with more care and skill than a plain stock unit. Third they rely on the stud wall system or similar system of legging and other legging systems will not work.

Are triscuits right for you? I can’t answer that because every theatre has different needs, space and personnel. Right or wrong depends on your mix of these things. Now here’s how to build a triscuit.

All framing is 5/4 stock @ 2″ true wide. Depending on the lumber dealers in your area, 5/4 nominal stock may be anywhere from 1″ to 1 3/16″ True thickness. Assembly of the frame is with one 4″ drywall screw, predrilled at each joint. Note that the screws at the corners must be off set to miss the bolt down hole. All joints are glued and the end grain pieces are coated with glue. After a 3 to 5 minute wait, they are coated again and then assembled.

The skin on both sides is 5/8 plywood. OSB would also work but add about 10% to the weight of the unit. The frame is completely brush coated with glue on the surface and the ply is then screwed down with 1 5/8″ screws on 6″ centers. The original design called for nails but I strongly advise screws. Great care must be taken at this time to insure that the unit is very flat and not skewed from corner to corner. Flip the unit over and repeat the skin attachment on the other side. When the glue has set, drill and counter bore the corners and your triscuit is done.

The Texas Triscuit

Due to problems with lumber supply of 5/4 stock in his region, Tim Francis, technical director at Trinity University developed what he calls a “Texas Triscuit”. Although the Texas Triscuit is not a stress skin unit, I include it here because of the close similarity of the units. In fact it should be obvious that one could very easily turn it into a stress skin by merely adding the second skin on the bottom.

The basic unit shares the same advantages of the triscuit. It is light, easily handled and stores in very little space. It has a few advantages over the original triscuit. It is actually lighter at about 56-lbs. total weight. It uses less material, thus cheaper. The frame is steel, thus virtually indestructible, the lid can be easily replaced when it is damaged or worn out. As might be expected there are also some disadvantages. The first is that the frame is made of steel and must be welded. If welding is beyond your means or skills, then you can not build a Texas Triscuit in your own shop. Although it will support as much weight, it is ever so slightly more “springy” under an active load. I suspect that adding a lower skin, even if it were only ¼” or 3/8″ instead of the 5/8″, and both skins were attached with a continuous bead of construction adhesive, then the unit would actually be stiffer than the original triscuit. Now to the point, here is the Texas Triscuit.

The frame is 1 ½”, 16 ga. square steel tube. The first step is to cut the steel to length and drill the four corner holes. Next all joints are welded with a 1/8″ bead all around. The most common problem in the construction is failure to maintain a square and flat structure during the welding process. The best way to achieve this is to build a jig of 2×4 flat on top of a worktable covered with hardboard. The jig should leave all the weld joints exposed. Next a series of tack welds will help to stabilize the unit. Tack the corners, top and bottom of each joint. Next complete all fillet welds on the inside seams, welding from the center of the joint out in both directions. The reason for this is to balance the stress and expansion/contraction that welding creates in all joints. Next weld the outside of the four corners, followed by the top surface. Carefully lift the frame from the jig, reverse it and finish the welds on the other side. Note that you can not be too accurate in building the jig. Every minute you spend on it will save you time in construction and help to insure accuracy. All the welds on the top, bottom and outside are then ground flush. Be sure to file or grind the insides of the exposed open tube at the corners to prevent finger catchers.

If you intend one lid to last the life of the unit the top may be fastened on with T nails and a construction adhesive. If you think you will replace the wood lid before the frame wears out, then drill point trek-screws are the answer. In either case, the fasteners should be on 6″ centers all around. The construction adhesive method will result in a slightly stiffer unit, but it is very difficult and tedious to remove if you want to change the lid.

As I mentioned earlier, both of these platform types are designed to be legged with a studwall system of supports. Later in this series I will be covering legging systems of many types.

As with all articles, if you are reading this in the archives, the illustrations will be missing. Drop me an e-mail and I will be glad to send them to you. Until next month, keep the green side up, don’t sweat the small stuff and remember.. It’s all small stuff!

Michael Powers

Categories
Platforming, things to stand on, stage decks, etc.

Platforming Article #2

The purpose of the lid is to support the point load of the actor or scenery, distribute it over as large an area as possible and transfer the load to the frame. The single most common lid material is ¾” thick plywood. While I have seen 5/8” thick and occasionally ½” thick plywood used for platform lids the amount of visible sag was unacceptable and safety was severely compromised. For normal theatrical use, non-dancing, the lid must withstand a bare minimum of 50 psf (pounds per square foot). For any kind of action, several actors close together, 100 psf is needed and for dancing 150 psf is an absolute minimum, 250 psf is better. For tap, clog, Riverdance etc. try to imagine the force of three or four dancers coming down at once. Dancers can generate a ten-fold force during a landing, stomp or tap maneuver. For example, three 110 pound ladies clogging in unison can create 110 lbs. x 3 dancers equals 330 lbs., 330 lbs. times ten equals 3,300 pounds of instant impact on a single platform. The exact load rating of any platform is a combination of all three components and is beyond the scope of today’s article. However, for the purpose of this discussion, an average platform will safely support about 100 psf in a static load situation. That means a standard 4’ x 8’ platform will support about 3,200 pounds evenly spread out over the entire surface. Of course that figure assumes that the legs and bracing and the stage floor below the platform are also capable of and designed to support that load.

The purpose of the frame is to support the lid and transfer the load to the legs and bracing. The type of frame material and its strength will determine the spacing between legs and braces. The frame should support the weight without bending more than 1/360 of the span between supports or a 1” sag in a 30’ span. This is about ¼” in an eight foot span or 1/8” in a four foot span. So, if you build a platform and it sags ½” when your actor stands in the middle, you need to cast smaller actors……opps…….what I meant to say was, you need to use larger framing boards or put the legs closer together.

The purpose of the legs and bracing is to transfer the weight from the frame to the floor under the platform and to hold the platform at the desired height and with little or no lateral movement. The methods of legging platforms are so varied that they can and will fill an entire article by themselves.

In the United States, the single most common size of platform is the four foot wide by eight foot long unit and the most common framing material is the plain old ordinary, SPF 2×4. Why are these the standard? It is simple economics and convenience.

Sheet goods are normally manufactured in the 4’ x 8’ size. While other sizes are available, they are more expensive per square foot and usually must be specially ordered. A 4’ x 8’ platform needs no sawing or cutting of the deck or lid material, it comes in that size to begin with. Strangely enough, even in countries using the metric system, sheet goods still are made to what they call “Imperial Measurement” and are 4’ x 8’. The measurement is metricized to 1220mm x 2440mm but it still equals four feet by eight feet. It might be interesting in a future article to investigate why sheet goods in those countries stayed at 4’x8’. Was it human scale, economics, convenience?

Now what kind of “sheet goods” are we talking about? Generally speaking we are talking about plywood but there are a number of products available with different advantages, disadvantages and cost factors. The following is a brief listing of some materials suitable for platform lids with some of their pros and cons.

Some Common Sheet Goods Used for Platform Lids in Theatrical Construction
Name Actual size Description Advantages Disadvantages Average Cost as of March, 2000 in US $$
Plywood, 3/4" AC
4' x 8' x 23/32" thick
5 to 7 layers of wood laminated to the nominal thickness. Layers have grain running 90 degrees to adjacent layers. "A" side is smooth and "finish" quality.
Strong, will support heavy loads if properly framed and supported. Available everywhere. Smooth surface can be painted and become the show surface.
Cost, March, 2000 price is about $32 per sheet. Moderately heavy at 75 pounds per sheet. May have voids inside that can allow point loads to penetrate.
$32.00
Plywood, 3/4" BC
4' x 8' x 23/32" thick
5 layers of wood laminated to the nominal thickness. Layers have grain running 90 degrees to adjacent layers. C side is plugged and rough, D side often has surface voids.
Strong, will support heavy loads if properly framed and supported. Available almost everywhere. Smooth surface can be painted and become the show surface. Price is usually $3 to $5 cheaper than AC Plywood.
Often very curved, usually has voids. 75 pounds per sheet May have voids inside that can allow point loads to penetrate
$28.00
Plywood, 3/4 CDX
4' x 8' x 23/32" thick
6 layers of wood laminated to the nominal thickness. Layers have grain running 90 degrees to adjacent layers. "B" side is smooth.
About 30% cheaper than AC Plywood
Rarely flat, large voids on D side. Must have some other surface for show side such as homosote plus masonite or luan.
$22.50
OSB, 3/4"
4' x 8' x 23/32" thick
OSB means Oriented Strand Board. Wood is shredded and glued up in a resin with the fibers roughly aligned in the direction of the board.
No voids, generally flat, structurally equal to or stronger than 3/4 AC plywood, but about the cost of CDX.
About 10% to 15% heavier than equal thickness of plywood, about 85 lbs. Per sheet. Must have a show surface of masonite or luan etc.resin dulls tools rapidly.
$22.50
Particle Board, 3/4" 4' x 8' x 23/32" thick, some brands 3/4" true.
Particle board is made of wood that is ground up roughly and glued up in a resin.
No voids, generally flat,but usually less than the cost of CDX.
20% heavier than equivalent thickness of plywood. Structurally weaker than 3/4 AC plywood. Very hard, screws must be pre-drilled for counter sinks to drive flush, edges and corners break off easily.
$19.75

Framing materials for stock platforms are also varied. The most common is the standard SPF 2 x 4. SPF means that the species of wood varies between spruce, pine and fir. The actual size is 1½” x 3 ½”. The reason it is the most common framing material is that it is the least expensive. Two by fours also are very durable, capable of handling a lot of use and abuse. They are heavier than most other types of common framing. Other types of framing materials are 1 x 6 pine and 5/4” by 4” or 5/4” by 6” SPF. Although 1 x 8 and 1x 12, 2 x 6 and 2 x 12 are also used for platforms, these are usually used for specialty or one of a kind units rather than “stock” units to be used over and over again.

One by six is the stiffest, lightest material. Five quarter is the strongest most expensive material. Two by four is the most durable. One by six makes a rather light but strong platform. However it does not stand up well to repeated banging about into and out of storage. The corners are particularly susceptible to being crunched and fasteners are prone to rip out. Two by four frames are very durable, hold fasteners well, rarely can be the finished frame the audience sees. Five quarter tries to get the best of both worlds, light, strong, and durable but it costs the most.

Framing patterns are the next item in a stock platform. The single most common is the 8’ stile with toggles on 2’ centers. The plan view is the same regardless of which material is chosen, see Illustration #1.

l1.jpgl2.jpg

Occasionally you might come across a platform built with only one or two interior braces but they have a noticeable sag or bounce as an adult walks on them and is totally inadequate for dancing or active theatrical blocking. The reason the particular framing pattern shown in illustration #1 evolved is because it is relatively strong, easy to build and uses the least amount of lumber of any acceptable framing method. While the method serves well, distributes the load evenly, it does have a drawback. The drawback is that it is not the most efficient method of supporting weight. A much stronger and stiffer framing method runs interior member along the long length of the unit instead of across it, see Illustration #2. This style of framing is not as common but is actually superior in most respects. The difference in strength is most noticeable when using 2 x 4 for the framing material. The standard method shown in illustration #1 requires a leg or support at 4’ intervals along the sides or 6 legs per unit. The method of framing shown in illustration #2 requires legs at 8’ intervals or only 4 legs per platform. It does use four more feet of framing material than the “common” method shown above.

l3.jpg

 

Another variation is a frame with only one toggle in the center at the four foot mark. While this variation will support 90% of the loads in theatre use, it will visibly sag or deflect between framing members. I do not recommend this framing method and when using 2 x 4 as a framing material, saves only about $2 per platform.

Methods of fastening the frame materials together are varied depending on the type of lumber you are using. Two by fours have been fastened together with 16d common nails for years. One by six or five quarter stock are usually fastened together with 12D nails. A slight variation is to use ring shank or spiral shank nails. The textured shank nails hold much better than the common nails, are just as easy to drive, are available in strings for pneumatic nailers but are about 10% to 15% more expensive. The main drawback is that they are very hard to pull out when you make a mistake. As battery powered screw guns become more common and available, fastening platform frames together with deck screws or drywall screws has become more and more the norm. Screws are roughly 4 times the cost of nails but hold much better, don’t work loose and can be easily removed if necessary. A skilled carpenter with a 16oz hammer can drive nails faster than he can drive screws but most ammeter, small or beginning workers can drive screws faster. Fastest of all, of course, is the pneumatic nailer. The nailer is a great equalizer in that the smallest 90 pound woman can drive nails as fast as the largest football linebacker and you can pick your workers for the muscle between their ears instead of in their biceps.

Although some people will swear by the use of glue when building platforms, don’t waste your money. It really does little or no good in the frame construction. Soft woods like pine, spruce or fir have very open end grain and end grain is a very poor glue surface. On the other hand when you fasten the lid to the frame, glue can increase the platform strength by as much as 20% depending on the number and spacing of nails or screws used to fasten the lid to the frame.

The last part of this month’s article is a brief description of the “other” stock platforms. Along with the standard 4’ x 8’ unit there are a number of other stock sizes; they are, in no particular order as follows. 4’ x 4’, 2’ x 8’, 2’ x 6’, 2’ x 4’, 3’ x 8’, 3’ x 6’ and the two triangle half platforms, the 4’ x 4’ and the 4’ x 8’ left and right. Framing techniques for these units is simply variations of the 4’ x 8’ stock unit, see illustration # 3.l8.jpg

l4.jpgl5.jpg

 

 

 

 

 

 

 

l7.jpg

 

 

 

 

ll6.jpg

 

 

 

l9.jpg

 

 

 

 

 

l10.jpg

 

 

 

 

l11.jpg

 

 

 

 

By using the group of stock platforms shown above, a wide variety of shapes and sizes can be assembled. With the addition of a few special built units the possibilities are endless.

One word of warning however. Stock platforms are not the end all be all of theatrical scenery. There are times when the use of stock platforms will cost more in time or money than building units to fit the size and shapes needed.

Now that we have looked at the basic platforms, the parallel and the “stock” unit, it is time to move on to more sophisticated and or special use units. Next month we will look at the Triskit and the Texas Triskit.

Until next time, keep the green side up, don’t sweat the small stuff …….. and remember…… it’s all small stuff.

Michael Powers

 

Categories
Platforming, things to stand on, stage decks, etc.

Platforming Article #1

It is difficult to say exactly how the Greek theatre used platforms as few descriptions of performances still exist. We can surmise that some appearances, disposal of dead bodies, etc. Availed themselves with rolling platforms. During medieval times Miracle Plays were performed on platforms that were basically wood planking laid over the beds of real wagons. I can not say if that is where our present term for rolling platforms originated or not.

In the renaissance stages were often set up as temporary structures in large ballrooms. When winter weather chased Shakespeare and his contemporaries indoors for the season, some of their stages were permanent and some were once again set up on temporary platforms in large halls, taverns and other places.

Today we continue the use of platforms in many ways. We use platforms to build sculptured unit sets, rolling platforms to bring on special pieces of scenery or even entire sets. We use platforms to build the very stage we act upon and sometimes we use them to set our audiences on.

Today we continue the use of platforms in many ways. We use platforms to build sculptured unit sets, rolling platforms to bring on special pieces of scenery or even entire sets. We use platforms to build the very stage we act upon and sometimes we use them to set our audiences on.

There are many different types of platforms and methods of building them. Which one is the best way or the right way? There is no such thing as best or right, only what is best in any specific situation. Right is determined by being the look the designer wants, the cost the production manager wants, the building method the technical director needs in relation to the time, tools, and kind of skilled labor available.

All platforms have a number of things that are in common. First is the “lid” or the surface that is walked on or that supports other scenery. The second is the frame or the structure that supports the lid. Finally there are the legs or the method by which the platforms’ height is achieved. Because theatre is notoriously short of space, time and money, platforms also have several requirements in common. They need to be able to be reused more than once, if possible. If they are to be reused, they need to store easily and in the least amount of space possible. If the platforms are used in a touring show, they need to be light and strong and easy to move. In repertory theatre or touring shows they need to be quick and easy to setup and takedown.

The first type of platform we will look at is the old standard parallel. The parallel platform has been around for over 300 years and it is still one of the most useful, overall, platforming techniques devised. The parallel is so named because the lid is removed and the frame then folds up, all the sides remaining parallel as they fold. There are three types of parallels: The standard parallel or closed corner parallel, the open corner parallel and the continental parallel.

Parallels are made up of a series of frames built very much like a standard theatrical flat without a cover. Notice however that the corner blocks are not held back from the sides of the frame as would be done on a flat. This is to provide a flat surface for the hinge to sit on. Some times the frames are simply cut out of a solid piece of ¾” plywood. The frames are then hinged together so that they create a square or rectangular foot print when opened out and fold flat for storage or travel. The hinging method is what determines the type of parallel.

Although I have drawn a 4’ x 8’ x 2’ tall parallel, parallels can be as short as 6″ or as tall as 20’. The very short ones can simply be made of hinged planks and very tall ones will have to be made of heavier and or thicker lumber, but the principal is exactly the same. A parallel can also be shorter or longer in either direction, 2’, 10’, 12’ 16’, 20’ or any other size that fits the specific need of the production.

As I said earlier, the thing that determines the type of parallel is the way it is hinged. Shown below is the method of hinging a standard or closed corner parallel.

The second type of parallel, the open corner type is built the same way except that the side frames are shortened in length by the same amount as the thickness of the end gates. This allows you to place all the hinges on the interior of the unit. It is much easier to construct but not quite as sturdy as the closed corner, relying more on the strength of the hinge to provide corner stiffness than the tight fitting wood to wood contact of the closed corner type of parallel. Hinging of the open corner parallel is shown below.

The third type of parallel is the “continental” type. The name came about because European theatres supposedly used this type exclusively. The continental type is the least sturdy of the types, the most difficult to construct, requires more middle gates and hinges. Why would someone build this type? The reason is that it folds up in it’s own length. Notice that both the other types, when folded, are as long as the length plus the width. There times when packing size is all-important. I most recently experienced this when sending out a USO tour to Guam and the Philippines. We were a small troupe going to small, out of the way bases so our total amount of gear plus personal luggage had to fit into 36″ x 36″ x 72″ crates. The Air Force gave us 40 shipping crates but everything, repeat EVERYTHING, had to fit into those crates. The platforming was all continental style parallels because it could be designed to fold and fit into those crates. The parallel frames were made of square aluminum tube rather than wood and the lids were an aluminum honeycomb stress skin, but they were still the good old reliable parallel. The hinge placement for a continental parallel is shown in the next illustration.

Parallels without lids are only flimsy frames. The lid is what completes the picture. The lid stabilizes the structure so that it will not fold up in use. It provides the horizontal stability to the entire unit. Before the development of plywood lids were made of planks laid parallel to each other with cleats or battens of wood fastened across the planks at right angles. The cleats also were spaced to make a tight fit inside the frame and gates of the parallel. Depending on the action of the performance, these lids often did not have to be fastened to the frame except by the snugness of the fit. This made setup and takedown on the road extremely quick. Today lids are usually made of plywood. Plywood is notorious for having some degree of warp, curl, or twist. It will rarely stay flat on top of the frame. As a result lids today usually have to be fastened down by some additional method such as loose pin hinges, bolt and wing nuts, drywall screws etc. One of the main mistakes made today is to eliminate the cleats or blocks on the under side of the lid as these provide considerable lateral stability in addition to any other method of attachment.

Other types of lids today include shop built stress skin, commercial stress skin, Triskets, the Texas Trisket and standard framed platforms all of which will be covered in this series in their own right.

This series of articles on platforms will continue for several months but I am always open to suggestions for other subjects.

For now, don’t sweat the small stuff and remember …………….. It’s all small stuff!

Michael Powers

Categories
Platforming, things to stand on, stage decks, etc.

Rotating Platform

What’s needed for a turntable?

  • A platform, any shape.
  • Wheels.
  • A pivot point.
  • A method of keeping it from wandering off the pivot point.
  • A drive. This can be hand driven or motorized.
  • A method to stop it from turning. A brake and/or locking device.

Let’s start with a basic, round turntable. The pivot point is in the center and the round platform doesn’t need to move anywhere else on stage. On paper, we start with a drawing of a circle. We add the required framing for the platform. We need to figure out the locations for all the wheels. We would use straight casters for this. The shaft of the caster must be aligned with the pivot point. This is very important! Each caster will be traveling on a continuous curved line that doesn’t change.
If you were to use swivel casters, it would be harder to get the turntable to turn in the reverse direction.

When you want to have a platform revolve around a single point, using a center pivot point is the way to go. This is easy to do. you can use flanges from you theater supply house. Or, you can also use a flange from your local plumbing supply house.
The one seen here is called a Key Clamp flange. Why is this a better choice? The pipe is locked into place via a set screw. This flange does NOT need threaded pipe. The plumber’s flanges does need threaded pipe.

The pipe is locked into the bottom flange via the set screw. The set screw of the top flange, mounted on the bottom of the platform, is left loose. This allows the unit to turn freely.

We used black tie line to turn this small unit. for larger turn tables, a metal cable would be used.

How do we figure out the angles for making this circle of wood? Think about geometry. A circle has 360degrees. Let’s say that our wood circle has 20 sections. 20 little tri-angles. 360 divided by 20 = 18. So, the bottom of each triangle has 18 degrees between the two bottom corners. We now need to divide 18 by 2, one for each side, and we get 9 degrees. (Actually, we will get 90 degrees minus the 9 degrees. Therefore, we must make a 9 degree cut at each end of our piece of wood.)
Do you want to double check our figures? 20 seams, 2 sides each seam. That’s 40 sides. 40 x 9 = 360.

In the photo, you may have caught that the sections are a little off. Well, we goofed. We cut the sections a bit too long. Since we had just two hours to make this platform turn, we had to be creative right there on stage.

Categories
Platforming, things to stand on, stage decks, etc.

Turn Tables

It’s very important to spread the glue out evenly.

Clamping with even pressure will assure a good grip. The turntable itself is made up of three layers. The top is 3/4″ ply. So is the middle, but this layer is 4″ smaller the the top & bottom. The bottom layer is 1/4″ ply.

Christina is laying out the casters in a circle. The base is a 6’x6′ platform framed with 2×4 and covered with 3/4″ ply. The casters are being placed on the base with the wheels facing up. The round turntable will sit on top. In the center will be a hole for a guide center pin.

Christina is laying out the casters. Notice she is using a long straight edge (a 6′ level) to make sure the wheels are parallel to each other and thus, perpendicular to the pivot point. You can also do this using a simple piece of string and lining up the center bearing pin of the wheel to the string.

I’m not sure this will work, but the photo here is a link to a MPEG video file. It’s just under 3 megs in size and you’ll need some sort of video player plug in working…

Rico is fitting the drive wheel to the turntable’s base platform. This will have a handle attached and will be connected to the turntable via 1/8″ cable.

The casters are placed to help guide the drive wheel. Otherwise, the drive wheel would keep popping up out of the hole drilled into the platform below.

The cable would keep slipping on the wooden wheels so we had to add some tension. The turnbuckle and pulley allowed us to vary the tension as needed.

Categories
Platforming, things to stand on, stage decks, etc.

Caster Corner & Plates

It is made of 1/4″ steel plate & angle iron. As you can see, it fits the 2×4 nicely. Countersink the holes and the platform lid sits flat.

The holes in the angle plates are to screw into the bottom of the platform’s frame. A hole is drilled into the side to allow another platform to be bolted to this one.

Here it is in action. This particular frame is part of a tree base being built for Into the woods . The lid is being left off so a technician can be inside the tree to move it on & off stage. See the page “Trees”, Drilling holes in the sides of the metal holds these 2×6 pieces square.

Categories
Platforming, things to stand on, stage decks, etc.

Platforming

To see a larger version, click on the board.

In other words, where do the wheels go?

More questions to think about:

  • What is the elevation of each level of platforming?
  • What is the height of the caster we’re using?
  • Do we use straight or swivel casters?
  • How do we get the platform to rotate and not go where ever it wants to?
  • How do we stop it from rotating? (Lock it in place)
  • How do we get it to turn?

This is what the full stage looks like.

A curved platform is pretty easy to build. The curved front is cut from a single piece of plywood. the framing members were cut from the scrap that was created. The front is covered with a  thin plywood that is bent, gently. The top was then covered with a sheet of ply and the front edge was trimmed.

Categories
Platforming, things to stand on, stage decks, etc.

Homasote

homosote.jpg

For info about homasote: www.homasote.com. DON’T write to our site. We don’t sell, manufacture, supply, etc… this stuff.

Homasote is a gray board that is made out of paper. It comes in 4’x8′ sheets and is 1/2″ thick. You’ll find it in almost any school being used as bulletin boards. you can push pins into it with ease. So, why on platforms? If you cover the platform with Homasote and then cover that with muslin it can be painted very nicely and it becomes very quite to walk on.
Note: We are NOT suppliers! I’ve gotten a few emails asking me for prices and such. Call your local lumber yard/building supplier. I don’t think Home Depot has it.
 

Categories
Platforming, things to stand on, stage decks, etc.

Plywood

I'm only going to get into the plywood we use most often.
Plywood comes in standard 4'x8' sheets and is always square. The thickness we use most often are: 1/8", 1/4", 1/2" and 3/4"

  1. 3/4" plywood.
    used most often for covering platforms. it is very strong and is fairly rigid.
  2. 1/2" plywood.
    We use 1/2" for building a lot of props, boxes, furniture parts. It's lighter then 3/4" ply. Cheaper too.
  3. 1/8" & 1/4" plywood.
    Great for making hard covered flats. The thickness depends on how rigid you need the flat to be. you must also take into account how much you need your flats to weigh. If you're flying your flats, you may wish to use the 1/8". That is if you're not going to soft cover them.

Grades of plywood.

Plywood comes in several grades. The grade refers to the surface covering. The better the grade, the nicer the surface. The grades are represented via letters, A, B, C, D, X.

  1. AA is great stuff. It is smooth on both sides with no knot holes. It's used to build nice furniture type objects. Book shelves that are open, thus allowing both sides of the plywood to be seen

  2. AC is more common. One side is the good stuff and the back is ok. We used AC for flooring that is going to been seen by audience members. That is, seen up close and that is not going to be covered with carpet, etc.

  3. CDX is ugly stuff. But it's cheap and works. The surface has big unfilled knot holes on the back (D side). Keep in mind that since this is just the surface ply, it doesn't show through as a knot hole in a piece of wood would. This is perfect plywood to use on platform tops when the platform is also getting covered with something like Homosote.

  4. I'm starting to use OSB. It's ugly and heavy. But it's cheap and strong. As strong as AC ply and as cheap as CDX. It will dull your saw blades faster because of the resin used to glue the Oriented Strands to form the Board (hence OSB) together.

Some do's & don'ts.

  • Anything that is taller then you are can be hard to handle. This stuff can be heavy.
  • Do ask for help when moving heavy plywood.
  • Always have assistance when cutting full sheets with a power saw.
  • Be careful of splinters! Ply tends to give them easily.
  • Ply is much stronger along the grain.
  • Store it either flat or as close to vertical as you can. If you lean it against a wall, at an angle, it'll warp.

The spreadsheet below is copied from thePlatform article written by Michael Powers. Check them out. They're good stuff.

Some Common Sheet Goods Used for Platform Lids in Theatrical Construction
Name Actual Size
Description
Advantages
Disadvantages
Average Cost as of MArch 2000 in US $$
Plywood, 3/4" AC 4' x 8' x 23/32" thick
5 to 7 layers of wood laminated to the nominal thickness. Layers have grain running 90 degrees to adjacent layers. "A" side is smooth and "finish" quality.

Strong, will support heavy loads if properly framed and supportedvailable everywhere.Smooth surface can be painted and become the show surface.

Cost, March, 2000 price is about $32 per sheet. Moderately heavy at 75 pounds per sheet. May have voids inside that can allow point loads to penetrate.

$32.00

Plywood, 3/4" BC 4' x 8' x 23/32" thick 5 layers of wood laminated to the nominal thickness. Layers have grain running 90 degrees to adjacent layers. C side is plugged and rough, D side often has surface voids. Strong, will support heavy loads if properly framed and supported. Available almost everywhere. Smooth surface can be painted and become the show surface. Price is usually $3 to $5 cheaper than AC Plywood. Often very curved, usually has voids. 75 pounds per sheet May have voids inside that can allow point loads to penetrate
$28.00
Plywood, 3/4 CDX 4' x 8' x 23/32" thick 6 layers of wood laminated to the nominal thickness. Layers have grain running 90 degrees to adjacent layers. "B" side is smooth. About 30% cheaper than AC Plywood

Rarely flat, large voids on D side. Must have some other surface for show side such as Homosote plus masonite or luan.
$22.50

OSB, 3/4" 4' x 8' x 23/32" thick OSB means Oriented Strand Board. Wood is shredded and glued up in a resin with the fibers roughly aligned in the direction of the board. No voids, generally flat, structurally equal to or stronger than 3/4 AC plywood, but about the cost of CDX.

About 10% to 15% heavier than equal thickness of plywood, about 85 lbs. Per sheet. Must have a show surface of masonite or lauan etc. resin dulls tools rapidly. $22.50
Particle Board, 3/4" 4' x 8' x 23/32" thick, some brands 3/4" true. Particle board is made of wood that is ground up roughly and glued up in a resin. No voids, generally flat, but usually less than the cost of CDX. 20% heavier than equivalent thickness of plywood. Structurally weaker than 3/4 AC plywood. Very hard, screws must be pre-drilled for counter sinks to drive flush, edges and corners break off easily. $19.75
Categories
Platforming, things to stand on, stage decks, etc.

Recycling

How to recycle for safe and efficient use of materials?

  • Forget about the sledge hammer attack method!
  • Use your tools to take the set apart. Sorry, I know that breaking stuff is a perk.
  • Practice common sense when building the set.
  • Remove all metal from all wood. (Nails, Screws, Bolts, Staples.)
  • Create an efficient storage system. I know that most schools have a problem with storage. Click on Storage for some ideas.
  • When making soft covered flats, don’t use glue on the toggle. Then cut the cloth from the center and save it to make another smaller flat.
  • If the ends of lumber is just too damaged from nails or screws, simply cut the end off and keep the good stuff from the middle.
  • Save all bolts, nuts and washers.
  • Toss all bent nails and used screws.
  • Screws can get burrs when driven and these can cause injury when the screws are re-used.
Categories
Platforming, things to stand on, stage decks, etc.

Lumber

 

Name

Actual

Use

1"x3" 3/4"x2 1/2" Used for framing flats.
1"x6" 3/4"x5 1/2" Used for framing door flats where extra rigidity is needed. Also can be used for framing light weight platforms. Platforms using 1"x6" need more legs and extra bracing then platforms using 2"x6"
2"x3" 1 1/2" x
2 1/2"
We often use this for stair railings, furniture parts, diagonal bracing and more.
2"x4" 1 1/2" x
3 1/2"
Platform legs, railings, heavy duty flat construction, medium duty platform framing. These are also used for framing houses, wall studs, heavy duty diagonal bracing…
2"x6" 1 1/2" x
5 1/2"
Platform framing, narrow stair steps (treads), stair risers.
2"x10"
2"x12"
1 1/2" x
9 1/2" &
11 1/4"
These two are most often used for stair risers (sides) and for heavy duty beams under platforms. Let's say we wished to have an open span of 12 feet. You could use a few 2"x12" beams, with proper legs at each end, to hold up your platforms

The Actual dimensions may vary from wood to wood. You should always double check the actual size before finalizing your cut lists. Let's say your cut list calls for 1×3 to be cut to 3'7" for the toggle of a 4×8 flat… If the 1×3 were to be 2 3/8ths instead of 2 1/2", the flat would be just a bit narrow.