# Need Help - Stage Effect: Trying to Lower Platform



## MJCochrane (Aug 18, 2012)

We are doing a new play festival and I am the scenic designer for it and for one of the plays the there are two actors standing in quicksand. The effect that we want to happen throughout the play until they get out of the quicksand which isn't until the end is for the platform they are on to gradually lower so they appear to be 'sinking' into the quicksand.

The platform I am currently planning on having at 4'x4' with it being 4' high as well. I'd be looking for the platform to start at it's normal 4' height and drop to around 3'.

I have been looking around at various ideas and equipment but am not sure how to do this, what equipment is out there that could help me with this? Anyone have ideas? 

Also the platform would need to be made stable to walk and play on for the plays before and after it in some way, it is the last show before an intermission so I have plenty of time to reset it to be walked on after. I am the scenic designer for the play festival but since it is a small company am essentially also given the responsiblities of TD and carpenter in trying to figure out how to do it and so on.

Thanks for any help, would love to be able to actually do this!


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## Footer (Aug 18, 2012)

How long is the play? Are they actually going to be using sand? 

You could always use a bottle jack in each corner of the platform.


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## MJCochrane (Aug 18, 2012)

It hasn't been fully rehearsed yet but looking at being a 10 Minute Play, so yes I realize it's trying to do a lot for such a short play but I'm looking at right now about $200-300 total for lumber for what we need with plenty of budget to spare and time to figure it out so currently the director and I are still trying to pursue it. The rest of the design consists of this platform I need help with and then four other platforms that are also 4'x4' and connected to this platform each by a ramp, with each of these platforms being 8" off the ground. There will also be one table, 4 dining room/office type chairs, 2 wood benches all furniture and platforms I'm currently planning on painting black with some gray and green in as well.
I have looked into both bottle jacks and floor jacks but all seem to go only from a few inches to about 24" max. And I'm looking to drop from 4' to around 1'.


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## sk8rsdad (Aug 18, 2012)

Do a search for "scissorlift table", or "stage elevator". There are a number of companies that will rent you a stage elevator. You can likely purchase or rent a suitable scissorlift table but they are not normally intended to lift people so understanding the safety issues like crush points, guards, and rate of descent would be prudent.


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## techieman33 (Aug 18, 2012)

MJCochrane said:


> It hasn't been fully rehearsed yet but looking at being a 10 Minute Play, so yes I realize it's trying to do a lot for such a short play but I'm looking at right now about $200-300 total for lumber for what we need with plenty of budget to spare and time to figure it out so currently the director and I are still trying to pursue it. The rest of the design consists of this platform I need help with and then four other platforms that are also 4'x4' and connected to this platform each by a ramp, with each of these platforms being 8" off the ground. There will also be one table, 4 dining room/office type chairs, 2 wood benches all furniture and platforms I'm currently planning on painting black with some gray and green in as well.
> I have looked into both bottle jacks and floor jacks but all seem to go only from a few inches to about 24" max. And I'm looking to drop from 4' to around 1'.




Your first post reads like you only want to drop from 4' to 3', I'm sure that's why kyle suggested the automotive jacks. I don't think you would have enough control for a 10 minute drop with a bottle or floor jack though. I was going to suggest a scissor jack on each corner since that would give you much more control, but I don't know of any that would give you anywhere close to 3' of travel.


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## MJCochrane (Aug 19, 2012)

Thank you all for the feedback! If you think of anything else please post it! 
I've been looking into the several kinds of jacks: floor jacks, bottle jacks, hi-jacks, hydraulic pistons, stage elevators and table scissor lifts; it looks like a table scissor lift would probably fit our needs well although I'm not so sure about for both our budget as well as the fact it is not meant for humans to stand on although looks like it should be safe enough, I'll be looking into that more.
I'll be having my next meeting with the director and design team this week and will probably be making the decision then or soon after whether to go through with it.
Thanks again!


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## chausman (Aug 20, 2012)

Can you explain again, how far is it supposed to travel, and how long is the drop supposed to be? I think we still have some confusion.


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## MJCochrane (Aug 20, 2012)

chausman said:


> Can you explain again, how far is it supposed to travel, and how long is the drop supposed to be? I think we still have some confusion.



Travel - Start at 4', drop to 1' over the course of around 8-10 minutes.


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## jonliles (Aug 20, 2012)

My 95 Ford Ranger used a Scissor Lift Screw Jack ... it's total travel was about 20". It's not the 3ft you want, but it would be easy to have a couple of stage hands lower the jack.


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## StNic54 (Aug 20, 2012)

You might be overthinking it - check with some old stagecraft books - you may find some design for a lift that doesn't need hydraulics, necessarily, and I'd be careful using anything like a standard jack that might be unpredictable. British Theatrical Patents, Special Effects in Motion Pictures, Secrets of Hollywood Special Effects, Technical Design Solutions for the Theatre

I would think there could be a way to design a threaded jack that a technician could manually lower, if budget is a concern.


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## BillESC (Aug 20, 2012)

Think threaded rods, sprockets and chain drive w/variable speed motor. That will give you an extremely smooth drop.


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## FatherMurphy (Aug 20, 2012)

A low-tech solution might be a long, sloped wagon underneath the 'quicksand' pit platform. Roll the ramped wagon slowly from one side to the other, as the actors equally slowly walk/crawl down the ramp. The actors would appear to be sinking behind the facing of the platform, and the construction and operation would be pretty cheap and simple.

What's the sightlines to the surface of the pit platform like? Will anyone in the audience be aware that the actors are dropping into an open hole in the platform deck, or do you also need to work out some sort of slit in spandex to make the illusion work? Or are they completely hidden behind a groundrow?


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## Van (Aug 20, 2012)

I really like Father Murphys Idea but I think you may be missing the point of using a bottle jack. Just because the jack has a throw of 20 inches doesn't mean you are limited to a 20" throw. Constructing a lever system that moves the fulcrum point closer to the point of travel is a realativly simple prospect. Since you are only talking about compensating for the mass of two actors the mechanical advntage lost by the movement of the fulcrum really should impact the ability of the jack to perform. Rather than attempting to run the trick with the stock relief valve I would look at removing and replacing it with something which has a finer control OR using a pnuematic over Hydraulic jack which allows for a regulated realease through an easily obtainable air valve.


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## MarshallPope (Aug 20, 2012)

A similar idea to Father Murphy's might be to build the sloped wagon that would roll from the high end to the low end, but to add a castered platform to the top of the wagon with a bottom edge angled to match the top of the bottom wagon. That way, when the wagon was rolled to the side, the top platform would roll down the ramp while staying in it's original x/y position.


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## sk8rsdad (Aug 20, 2012)

I still prefer the idea of a scissorlift table. There is no danger of it ever resulting in an uncontrolled descent, as the wedge design, and piston with bleed valve could. If the motor or crank isn't turning then the table stays where it is.


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## kicknargel (Aug 22, 2012)

How would you get a scissorlift table to descend over the course of 10 minutes? Also, they cost around $2500, before the necessary safety interlocks.


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## sk8rsdad (Aug 22, 2012)

kicknargel said:


> How would you get a scissorlift table to descend over the course of 10 minutes? Also, they cost around $2500, before the necessary safety interlocks.



I was considering the kind where the scissor is operated by a rotating threaded rod, and not a hydraulic version, which may be where our difference of opinion is coming from. With the threaded rod, it only moves when the rod is turning. Turn the rod slowly to go down over 10 minutes. 

Even with the hydraulic ones, the material handling cart versions can be found for $250 to $500 depending on capacity. However, these would have similar issues to the bottle jack proposals since the descent is less controllable. I'm not sure what sort of interlocks would be required for this application. I would have thought a guard skirt around the moving bits would be adequate.


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## MPowers (Aug 22, 2012)

BillESC said:


> Think threaded rods, sprockets and chain drive w/variable speed motor. That will give you an extremely smooth drop.



Bill's idea is excellent, if you go this route, use acme threaded rods, they are designed for weight bearing positioning uses. Drive can be a hand crank and stage hand.

McMaster-Carr

Method: 
4 rods, one just beyond each corner of the unit. Captive at top with flange mount pillow blocks, at the bottom with a clamp on shaft collar and a closed shielded thrust bearing. # 40 roller chain sprockets on each rod. Roller chain to a hand crank or motor and all rods will spin in perfect unison.
McMaster-Carr
McMaster-Carr
McMaster-Carr
McMaster-Carr


Platform: extend opposite side frame members 4" to 6" beyond the platform in each direction. Drill vertical holes through the frame members and attach Acme flange nuts.

The flange nuts support the platform and when the crank is turned, the platform rises or drops.


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## kicknargel (Aug 23, 2012)

sk8rsdad said:


> I was considering the kind where the scissor is operated by a rotating threaded rod, and not a hydraulic version, which may be where our difference of opinion is coming from. With the threaded rod, it only moves when the rod is turning. Turn the rod slowly to go down over 10 minutes.
> 
> Even with the hydraulic ones, the material handling cart versions can be found for $250 to $500 depending on capacity. However, these would have similar issues to the bottle jack proposals since the descent is less controllable. I'm not sure what sort of interlocks would be required for this application. I would have thought a guard skirt around the moving bits would be adequate.



I guess I've not seen one of these. Have a link or a vendor? Could be useful.


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## sk8rsdad (Aug 23, 2012)

I haven't found a vendor on-line but I did find a couple of links that might lead to a vendor.

Scissor Lift Jack Equations - Engineers Edge

The above link references an engineering/fabrication firm that does theatre work. Their website won't render in Chrome, Firefox, or IE.
SHOW CANADA - Theatrical Equipment,Specialized Architecture,Architecture Spcialis,quipement de Scne

Then there's this patent that might help locate a company.
Patent US20110037039 - ELEVATION MECHANISM - Google Patents


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## Van (Aug 23, 2012)

Personally I think you are going to find that obtaining a gear motor that has enough torque at an appropriately slow speed to turn Acme Threads < or any other kind for that matter> with a significant load on them to be prohibitively expensive. I like the idea of 'screw jacks' for raising and lowering platforms, it's just for a one-off festival rig you need something quick, dirty and safe. I'm not saying there aren't a million ways to do it but building a four-screw jack system with apropriate drive motors and control interface, is going to run somewhere North of $1k. It will also require Welding, metal-working, electrical electronic and engineering skills.


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