Platforms

[Charc]

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?

[curtg]

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.

[HHBucket]

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?

[Van]

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.

[derekleffew]

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.


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.

[Van]

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.

[derekleffew]

Van, do you connect your triscuits with biscuits? Too many carbs.

[Van]

Originally Posted by derekleffew

Van, do you connect your triscuits with biscuits? Too many carbs.

Nope but I connect my Biscuits with Gravy !!!

thus the Journeymans belly.

[curtg]

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.

[gafftaper]

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