Trapdoor hinge

jds10011

Member
Our usual trapdoor involves the hinge set flush with the deck so that nobody trips when it is closed. Of course, this means the door itself can only go as far as vertical when open. The director is eager for the door to open fully in a particular scene, so it can lay upstage on the floor in a particular moment. (Obviously, care will be taken not to trip over the door or fall down the hole until it is closed again.) However, I'm not sure how this can be achieved without the hinge pin sitting above the stage deck and everyone tripping on it when the door is not in use. Suggestions? Thanks.
 

RonHebbard

Well-Known Member
Premium Member
Our usual trapdoor involves the hinge set flush with the deck so that nobody trips when it is closed. Of course, this means the door itself can only go as far as vertical when open. The director is eager for the door to open fully in a particular scene, so it can lay upstage on the floor in a particular moment. (Obviously, care will be taken not to trip over the door or fall down the hole until it is closed again.) However, I'm not sure how this can be achieved without the hinge pin sitting above the stage deck and everyone tripping on it when the door is not in use. Suggestions? Thanks.
@jds10011 Consider Soss (Brand) hinges.
Ron Hebbard
 

almorton

Well-Known Member
You want a hinge as often used on bars which have a double pivot. Sometimes called a counter flap hinge.
 
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bobgaggle

Well-Known Member
how about no hinge? just a man hole cover with a finger hole to lift it, and make sure no body is wearing stilettos lol...
 

Van

CBMod
CB Mods
Premium Member
+1 for Soss hinges!
 

jonares

Member
Along the lines of Soss (brand) hinges, you're looking for heavy-duty concealed hinges. I have a collection of them I've used for trap doors. Last time was for "Black Comedy" - I looked back to see who/what I bought, and found it was from Rufkahrs Hardware - but looking at their website that looks like 1992, I can find this (for reference) - http://www.rufkahrs.com/hardw4/hinge2.html
What I have can do a full 180 degrees, and lay flat on the floor once opened.
 

Benjamin Fink

Active Member
I've found some other results by searching for a flush mount 2-pin hinge, including this one on Amazon. It looks like most of the hinges available for sale are designed for light use for table tops or boat hatches, so I'm not sure how large of a trapdoor you could support with them.

If you have a stock of hinges and want to make a set instead of buying new, the Technical Design Solutions for Theatre Volume 1 has instructions to build "A Simple Flush-Mount Hinge" on page 195. (I would highly recommend purchasing all three volumes of the series, as there are a lot of great write ups of various solutions.) If you don't have the books, you can find some scans of the relevant pages online. You will take two matched hinge halves and bend a pin into a u-shape to go through them so they're aligned similar to the ones Jonares, Beachbum, and I linked. That way you could size up to a beefier hinge without going up to the full SOSS price.
 

MPowers

Well-Known Member
I always built drop and slide trap doors. They open faster, are completely out of the way both on stage and under stage. For those not familiar with drop and slide doors, the "door"rides in a frame the is hinged to the underside of the deck at one end and is long enough for the door to slide completely clear of the opening. The frame only swings down enough for the door to clear the underside of the deck around the opening. My go-to actuator was a rodless pneumatic cylinder for the slide motion and De Staco cam lock pistons for the drop and rise. The cam lock was secure in the closed position even with a loss of air pressure.
 

bobgaggle

Well-Known Member
For those not familiar with drop and slide doors, the "door"rides in a frame the is hinged to the underside of the deck at one end and is long enough for the door to slide completely clear of the opening. The frame only swings down enough for the door to clear the underside of the deck around the opening. My go-to actuator was a rodless pneumatic cylinder for the slide motion and De Staco cam lock pistons for the drop and rise. The cam lock was secure in the closed position even with a loss of air pressure.

Do you have a drawing of this you could share? I've never had the chance to do one of these and always wanted to figure out a simple solution. I just keep staring at the moon roof in my car, trying to figure out how to do that on stage. I'm also interested in the cam locks failing safe, how's that work?
 

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