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Platforms

Discussion in 'Scenery, Props, and Rigging' started by Charc, Jun 9, 2008.

  1. Charc

    Charc Well-Known Member

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    Okay, okay, so my carp terminology is low, to say the least.

    I'm talking platforms here, and I'd love some clarification.

    So let's start with the basic parts, three main components, right? Lid, Stile/Rail, Leg.

    My main question is this, where do the legs go? I've seen legs both directly under the lid, along the inside of the stile/rail, and underneath the stile/rail, scabbed on. I've heard/seen some good points for both. Before I go into my explanations, I'd like to hear some of yours. Where do you guys put your legs? As a subtopic, diagonal bracing, what do you do there? What about thru-bolts, lag screws, or dry wall screws?
     
  2. curtg

    curtg Member

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    I prefer to place the legs under the frame, rather than just inside the frame against the bottom of the lid. The platform's frame supports the lid, the legs support the frame. Gravity will hold things together rather than nails or screws.

    Building is easier running the legs just inside the frame. But, the load is supported by the fasteners and the the lid.

    My legs are 2xs to match the frame with a second board, or metal gusset, that extends inside the frame to facilitate attaching the legs.

    You dramatically increase the strength of your legs by fastening them to both the ground and platform.

    Diagonals are needed to account for the lateral forces. I like using plywood sheathing or cross frames. These materials do not have to be heavy duty if they are applied in a balanced manner. By balanced, one support would handle a pushing force while another would handle a pulling force.
     
  3. HHBucket

    HHBucket Member

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    A lot of it comes down to application. I've recently been working mostly with raked decks so I don't use individual legs at all and have been building Stringers (basically a 2x4 mini stud wall) instead.

    If my platform is level I tend to put my legs inside the frame and through bolt them in place. The weight of the plat is carried on the bolts, just as the last post suggests, but it is more than sufficient for the job.

    Compression legs (placed under the frame, not inside) are great too but I work mostly with high school students now and until your platform is in place the scabs of a compression leg are easier to rip off than a bolted leg inside the frame.

    X bracing? I use pretty much whatever is around. Because I put my legs inside the frame I try to have as much 2x4 around as I can to plumb up the bracing to the frame, it makes facing plats much easier.

    What are you doing?
     
  4. Van

    Van CBMod CB Mods Premium Member

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    Legging the plats. I prefer using "compression legs" I use 2 pieces of 1x4 stapled and glued together, one peice runs to the top edge of the framing and receives the bolts, screws, or what ever you are using to secure the leg to the frame, the other just sits under the framing. Compression legs, when used on shorter elevations also help to eliminate the need for X bracing. Another good thing about compression legs, they present a surface which is flush with the framing and therefore make an excellent place to attach facing to. If one doesn't use compression legs then one needs to use " Box Framing"; the aplication of a 1X2 around the bottom of the legs, basically mirroring the framing above it, box framing present an excellent surface for attaching the bottom of facing < luan, masonite, foam> and can often be used as a place to sink a few screws for added stability. As HHbucket stated I also use " Pony Walls" or "Knee Walls" to assist in the creation of rakes, and larger decked areas. It's very easy to store a bunch of 7 1/2" tall by 12' long ponies then just pull them out whe you need a 1 foot platform. Using the Pony / stud wall system, where applicable is also much more stable for supporting taller platforms, it does, however require some form of diagonal bracing, be it in the form of a cover, luan or plywood, or a couple of applied peices of 1/4.
    one not on compression legs, when using them the inner leg should not touch the underside of the lid. This practice will help eliminate squeaks , and prevent the lid from being forced loose in the event that the outer leg is too short and not meeting the bottom of the framing.
     
  5. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Note that, although not explicitly stated, Van frames his platforms with 1x stock. This is fine for a pro shop, but considering the cost difference between 1x4 and 2x4, I would not recommend it for amateurs.

    I like compression legs of 2x4 for 2x4 framed platforms, often attaching the corner legs in an L shape, then two "keystones" of 1/2" or 3/4" plywood 3"x8" screwed or stapled into the leg and the platform framing. For internal legs, no L shape. For all, unless the facing is substantial, 1x2 stock for diagonal bracing, attached with staples as screws tend to split the narrow wood.

    Charc, the components of the platform are named after those of the flat, thus rails, stiles, and toggles (on 2'-0" centers).

    Attaching legs with 3/8" x 3.5" carriage bolts is passe, leads to swiss cheese corners for reusable stock, and I can't begin to count the number of threads I've chased with a 3/8-16 die. Plus, it's the method my nemesis advocates.:(

    [​IMG]
    These work well, but don't solve the problem of the leg not being flush with the framing, thus requiring extra blocking for facing, and still require cross-bracing of any leg 2'-0" or longer.
     
    Last edited: Jun 9, 2008
  6. Van

    Van CBMod CB Mods Premium Member

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    I should also point out that I have mostly moved from the realm of "standard" platforms and ventured into the land of "Triscuits" or stress skinned platforms. triscuits virtually eliminate the need for legs and let you move completely into the realm of pony and knee wall construction, for the support of you platforms. BTW I've found an excellent way to manufacture triscuits. By cutting a piece of 4x8x3/4 ply dead center, you wind up with a piece of 3' 11-11/16" x 4 now trim it in the other direction so you have a 3' 11-11/16" square piece. use these as the tops and bottoms of your triscuits and you have a great "no squeak" platform layout. Just use a couple of pieces of 1/8" luan as spacers when you do the layout and Viola' perfect sub floor. Actually I should note that this technicque was perfected by CB Member SweetBennyFenton, my former MC/SF.
     
  7. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    [user]Van[/user], do you connect your triscuits with biscuits? Too many carbs. :dance:
     
  8. Van

    Van CBMod CB Mods Premium Member

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    Nope but I connect my Biscuits with Gravy !!!
    :lol:
    thus the Journeymans belly.
    :oops:
     
  9. curtg

    curtg Member

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    The original post also asked about our thoughts on fasteners. While I introduced drywall screws to the local community theater scene 20 plus years ago, I try to avoid using them today. They are not strong enough. I use nails and bolts where there is going to be a shearing force. My platform lids are screwed down with deck screws.

    I am a proponent of supporting platforms with knee walls. It is how houses are built. The problem with them is storage. If I take them apart, I bundle and label the lengths of the boards for reuse. It is nice not having to cut pieces to length.

    Triscuits have intrigued me for years. Chapter 15 of Ken Horner's More Woodworkers' Essential Facts, Formulas and Short-Cuts, Cambium Press, 2006 not only describes how to build torsion boxes, but also has the formulas use to calculate their strength relative to other wood products. I would like to know what the optimum sizes are for theatre stock.

    Finally, getting back to set construction, I use a lot of metal gussets and corner irons with high quality waffle head screws instead of wood scraps. I also use 12' sticks of metal lath to tie flats together. These pieces are easy to store and reuse. And, over the long run, they are less expensive.
     
  10. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Search is your friend! I put together a thread on the topic with step by step pictures a while back. There are many options. I like mine because it's strong, quiet, and easy to build for educational theater. It's also highly recyclable.

    Hey Van/Sweetbenny I'm interested in triskets but have a hard time visualizing how they work. Any chance you could post some pictures of how your construction technique and how you put them together some time. Perhaps we could combine them with mine into a Wiki thread
     
  11. curtg

    curtg Member

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    Great presentation. I have one suggestion that could solve your platform squeak problem. Instead of attaching legs to each platform and flipping the 'bad boy' over, put your knee walls in place first and and have your platforms straddle them. The platform edges would rest on the same edges.

    I really like the 'neatness' of your work. Too often in community theater you get slapdash construction where the parts do not fit together.
     
  12. Van

    Van CBMod CB Mods Premium Member

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    Gaff, I think that's a great Idea. I'd be happy to work on an article relating my experience with Triscuits. A quick search on google will also link you to Yales website, wherein you can find a ton of info. I don't build mine quite as beefy as they do. I''m going to look into the book curtg mentioned as I'd like to get some more technical specs and do some calculations on exactly how much load my version will carry.
    As for the question of optimum size; I prefer to build mine as stated above, a 4'X4' < Nom> triscuit is just on the edge of "easy to move around" for a single stagehand. I build a few weird ones for filling in gaps in a floor , but mostly I stick to 4x4. Standard platforms, it's 4x8 and at the Portland Opera, and Acme Scenic we used to use what have locally become known as "Raker Decks" which are a 6'x8' deck 3/4" top framed with 5/4 x 6" mahogany, toggles are every 18" oc and the sides of every platform have an interlocking T&G setup. I'll work on drawing of my triscuits, and raker decks whilst I'm on Vacation.
     
  13. thorin81

    thorin81 Active Member

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    The whole standard platform thing is great! However, I have a question - what about really tall platforms? I have to build an 8' tall structure for Beauty and the Beast that everyone needs to be able to walk on. Do the same rules and techniques apply to this situation? Since it is so tall, will the sound board in gaff's presentation really do all that much? How do I get rid of all the sound from people walking on an 8' tall unit?
     
  14. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    I don't have any scientific proof but think of it this way.
    If you wanted to keep a drum head quiet you would secure it in as many points as possible and put a bunch of material in there to soak up the vibrations right. Well that's all a platform is. I think the key to the sound deadening board is when you walk on it it gives it a deeper solid sound more like walking on a floor than without.

    As for height, it's all about strong legs and cross bracing. My feeling is you could build platforms with the "stud wall" legs like I use 16' high with no problem... I've never done it, but the principle is the same be it 8" or 8'. The only difference is adding more cross bracing.
     
  15. Van

    Van CBMod CB Mods Premium Member

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    In Streetcar which we just closed I had a 16' long platform which was 10' in the air, supported on one edge by a 1x3x.089 steel frame, and the first 4 feet of the other end was supported by two steel "stud walls" it was sortof built like a 3'x16' tricuit with 6 pieces of 2x4x16 running the length of it sandwhiched between 3/4" ply. the rest of the set was all 3/4 ply ontop of ponywalls and stringers. we solved the drum problem by installing homosote ontop of the 3/4 then adding a layer of 1/4" MDF on top of the homosote. This works really well for sound deadening. You can also install a layer of 1/2" OSB ontop of the homosote then the MDF as a finished top if you are going to be having high point loads on it ie heavy loads on few casters. You can also use R15 interior insulation underneath a standard platform to help quiet them down. The most important thing to remember about sound dampening is that it's essential to think ahead. You can do lots of thing to quiet down a deck ahead of time but once the deck is installed it's very difficult to deal with noise. Oh BTW if you do install MDF ontop of Homosote, take a tip from me and by an industrial sized bottle of babypowder. you'll want to put a light dusting down on the homosote. This will keep the MDF from squeaking when it rubs against the homosote. The baby powder trick works well for squeaks between standard plats as well.
     
  16. lieperjp

    lieperjp Well-Known Member

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    That's true dedication right there, folks!!!
     
  17. malex

    malex Member

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    Hi Everyone,

    This is my first post on CB, I've been perusing all the posts for a few days and have to say that there is a LOT of really valuable experience in here. Thanks for the help so far.

    I am really interested in creating a whole lot of Triscuit Plats for my theatre. I've designed a show that has an excessive amount of plats on different levels. I created the multi level design for the express purpose of replacing the ancient, poorly built units that we have in stock.

    To get a grip on the triscuit theory, I made a prototype from scrap materials. My test unit is made from 1/2" CDX ply with ripped 1x4s for the guts. These came out to be 1 5/8" x 3/4" true size. I also didn't screw any of the frame members together; I just stapled them to the sheets of ply, using lots of glue. I had no intention of this unit being very functional, but to my surprise, when tested, it held my 190 lbs. with nearly no deflection.

    Here's the question: In light of finding success with greatly reduced materials, time and effort, are my triscuits still going to be effective and safe? If I keep this method, I would definitely move up to 5/8" ply and probably use stock 1x3's or 1x2's to cut out the ripping process.

    Please let me know what the community thinks and if anyone has built Tricuits with lesser materials than Yale suggests, please let me know of your success or failure.

    Thanks,
    Alex Amyot
     
  18. Van

    Van CBMod CB Mods Premium Member

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    Here At ART we build our triscuits with a 1/2" CD skin. We cut a sheet in half then rip a side off so we winfd up with a 4'-11 7/8" square, this makes layout of foors a lot easier, and less squeaky. For the interiors Yale suggests the use of ripped 5/4" stock, we used ripped 2x4 and wound up with 1.5x1.5" interior framming members and I have found them to be very sturdy. I have to say I would be extremely hesitant to go any smaller than 2x material however, especially depending on the species. I feel the real advantage that 2x gives you is in dynamic loading. I'm sure the 1x framed triscuits you mention are capable of holding your weight, my hesitation would arise when you begin to discuss dancing, fighting, or rapid movement on top of them. Thes are the factors that are going to truly test you loading capacities and 2x stock handles a shock load < ie much springier> much better than a 1x stock does.
    While we did not invest the R&D money that Yale did we did build several prototypes before settling on the model we now use. A CB member Sweetbennyfenton , my former Master Carpenter and present TD at Lewis & Clark College, is responsible for most of that work and has posted a couple of drawing here. While I say "Goodonya" for the move to triscuits I would caution you to upgradr your framing. I'm saying this, of course , assuming you maintained the traditional 18" interior framing layout, If you moved to 8" or less centers than You probably won't have a problem, however, I still feel the grading issues with 1x material usually lead to them being from younger, more brittle, and poorer quality wood.

    Hope that helps. Stop by the New members forum and Intro yourself, post a link to your website, we're nosey.
     
  19. Footer

    Footer Senior Team Senior Team Premium Member

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    I have built "Yale" triscuits for days on end, and they are nearly indistructable. For those, they suggest you use 5/8th ply but I usually go with 3/4 ply.

    All you ever wanted to know about triscuits.
    Tiny URL - create a shorter link

    I personally love them, they make dropping down a deck so much faster. However, before you go building them you have to completely rethink the way you go about a technical design for a production. You are no long building platforms and legs, you are building stud walls. You will also need to invest in 3 1/2" screws. If correctly made and maintained, a triscut and last close to ten years, twice the life of a standard 4x8.
     
  20. Footer

    Footer Senior Team Senior Team Premium Member

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    Totally possible, especially if you want an elevated deck. With stress skin platforms though, everything needs a stud wall, even a 1' riser.
     

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