Screen drop from a dead / non moving bar

[TomHoward]

Does anyone have any advice on what could be used to raise and lower on a whole screen on a non-moving 48mm bar?
The screen is a 4m electric roller screen, weighs around say 40kg. Two hanging points on shackles / wire rope.

Currently the screen is on a winch bar but this is a pain as it takes up a bar that is often needed for rigging / tabs etc.

I am aware of the double-drop screens that essentially use a second motorised mechanism to drop the first, but as an independent point is there anything off the shelf that could run this and all be mounted onto the 48mm bar?

The drop to operating position is maybe 2-3m and the drop to the floor if it were to reach all the way down is around 6m.
Something like a small winch drum motor with 2x wires, a couple of pulleys, off the shelf with limit switches somehow, wired back to a 240v switch?

Or any recommendations of companies for such a small job?

[Dave m]

One issue with a winch type arrangement is that you come under LOLER?
so annual inspections etc?

does it drop during a show? Or you just need it to be up high and be pulled down for shows?

I was thinking pantograph suspension?

[bruce]

could you use a "normal" motorised screen where the screen has a 2m black section at the top. Effectively a big long screen that drops down from high...

 

There's a name for them - can't remember it.

 

[TomHoward]

I’d thought I’d seen those long drop screens before but I couldn’t find much either. Currently we could fit the existing screen too, either it could be something 48mm mounted under the roof or something mounted in the loft also where the winches for the existing bars are.

This would never move in a show or with anyone underneath and we have annual LOLER inspections already, as we have 10x electric hoist bars plus some manual bars and a collection of loose kit. The screen is currently mounted on one of these 10x winch bars but it always uses up an upstage bar where we are a bit short.  

[mac.calder]

Asm used to make a steel band hoist that was pre asembled on a unistrut-esq beam with 2 attachment points. Jands used to make a derivative here in Australia which we used to use to create large double deploys for screens. It even came with the option of lighting bar with cable management if desired. 

 

They may still make it,  it's worth a look.

Edited September 26, 2022 by mac.calder

[timsabre]

If you google for "double drop" screen or "double motor" screen you will find some standard products of the double drop type where the screen casing drops down on cables

e.g. https://www.sapphireav.com/Sapphire-Smart-Move-4m-43-Two-Motor-Electric-Projection-Screen-Approx-Case-Dimensions-L-4317mm-x-H-250mm-x-D-170mm_p_524.html

[Stuart91]

16 hours ago, bruce said:

could you use a "normal" motorised screen where the screen has a 2m black section at the top. Effectively a big long screen that drops down from high...

There's a name for them - can't remember it.

I put a couple of these designs into installations. We had them manufactured by ECT, but I think they stopped offering them altogether. 

The key difficulty is avoiding the edges of the fabric curling in, so "tab tensioning" is a must. 

We also had a "Smart Move" screen that failed badly. Chewed its own hanging wires despite them being rigged perfectly straight. I've been very wary of them ever since. 

[Bryson]

My typical solution to this is additional black drop, as you say.  You can (within reason) order as much as you like added to the top when ordering.  

Here's an extract from the Draper order form.

 

[Stuart91]

Interesting to note that they will do a maximum a drop of 12ft. 

We did two that were 18ft tall (an 8x6ft viewing surface and 12ft of blank space above). I believe they needed a custom screen casing built - essentially a shortened version of the casing for a far wider screen to accommodate the amount of fabric that needed to go on the roller. 

 

[Bryson]

I *think* that 12' limit is on the height of the screen (reflective) surface, not the black - I'm assuming any larger means you have to have seams.  It may also be unique to that particular screen model, that was a midsize (Access FitE) screen I selected.

 

 

[mac.calder]

Extended leader screens often suffer really badly from warping and rippling, as the leader and the screen area react differently to temperature. Something to be aware of.

[sunray]

Yes the curling becomes a big problem. We were asked to provide a powered screen for a week run, we were of course very late rigging and when we started rigging on hanging wires it became apparent it was too low for some moving scenery. The only thing we had to lift it out of the way was another electric screen and literally suspended one from the bottom rail of the other. We intended returning the following day to make changes, but...

[dje]

Hoist UK Mini Pilewind sounds ideal for this. Mount the winch and 2/3 pulleys onto your existing bar (providing, of course, the weight is OK. If not, you may have to put the winch on the floor, or bolt it to the roof by other means and divert). Get the pulleys up high enough and hopefully you can avoid losing too much trim height.

[TomHoward]

3 hours ago, dje said:

Hoist UK Mini Pilewind sounds ideal for this. Mount the winch and 2/3 pulleys onto your existing bar (providing, of course, the weight is OK. If not, you may have to put the winch on the floor, or bolt it to the roof by other means and divert). Get the pulleys up high enough and hopefully you can avoid losing too much trim height.

Thanks for this. I'd found a bit on the Hoist UK pile winds but this looks like who to speak to.

Above the grid is a loft space full of criss-crossing RSJs that the existing bars and motors bolt back to - moving bars back to diverter pulleys and pile wound hoists and dead bars the wires just fix back to the RSJs on eye bolts. I'm thinking more now having thought about it and looked at it that installing something like this in the loft above the grid with diverter pulleys and installing the screen as an independent drop between two existing bars might be the best option, rather than rigging off the bar.

[Fleeting]

Good afternoon,

                 I recently did a extended black top Sapphire Screen for a school chapel. I think it was a extra 1.5m. The delivery time on a slow boat from country of origin was 12 weeks.

 

 

 

Edited November 4, 2022 by Fleeting