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DIY Chroma Key mount


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#1 Mike Nutt

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Posted 09 November 2005 - 10:20 AM

A pretty eccentric question, but:

So we recently built a mount for chroma-key paper in our studio. It's pretty simple right now: A ten foot steel bar is supported ten feet from the floor by pipe fittings that come off of the wall, attached by two flanges. At each end of the steel bar is a union so we can take the bar down easily to change the paper. However, now we have two related problems:

1. We have no good way to keep the paper from unrolling to the ground from its own weight (right now we're just using binder clips! Not good!).

2. We need a way to roll the paper up and down as it can't remain down all the time (students would destroy/trample/tear it).

Has anybody ever built their own chroma-key paper support? I'm thinking we need some kind of cam that fits inside the paper roll? Any ideas would be appreciated! Thanks, Mike
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#2 Tom Banks

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Posted 09 November 2005 - 11:53 AM

To solve the problem of it unrolling on its own weight, and depending on how big your role is, you can use clothes pins and clip the top of the roll on each side so that no more paper can be unrolled.

As for rolling it up, sounds like you may just have to do it the old fashioned way. If that isn't practical, you may be able to attach some sort of makeshift handle onto the inside of the roll that will make rolling it up easier.
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#3 Mitch Gross

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Posted 09 November 2005 - 02:27 PM

Spring clamps (aka pony clamps) are what I've always seen used to keep the paper from unravelling. Most pros don't bother to re-roll the paper, just slice it off and start fresh. I did see one rig where they cut a notch into the cardboard tube center of the roll and interlocked this to a crank pulley that they attached to the support bar. Some chain and a winch completed the rig. No clue where you'd go to get the parts, maybe automotive supplies?
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#4 Luke Prendergast

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Posted 09 November 2005 - 04:11 PM

Vertical blind roller could work.
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#5 Mike Nutt

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Posted 10 November 2005 - 08:24 AM

Yeah I guess pony clamps would work better than binder clips for the short term, but maybe I should explain a little more what we need.

This is mounted in a multi-use University studio. We have to be able to roll it up at least three or four feet after every use to access an electrical outlet that is unfortunately behind the paper (and to keep students from trampling it when it's not in use). So getting two faculty or staff members on top of ladders each time to roll it up and down and clamp it is kind of impractical.

Although the pros may cut it off each time, this is definitely not a "pro" situation. We're on a budget and this paper is not an expendable for us.

So yes - the crank pulley/winch system is what I'm thinking along the lines of. Has anyone ever made one of these or could you imagine what one might look like?
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#6 Mitch Gross

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Posted 10 November 2005 - 11:37 AM

Two quick & simple solutions. First, put an extension cord on that damn outlet so you don't have to worry about access anymore. Second, rather than an expensive pully system, screw a ring-bolt (a bolt with a large circular hole in the top) into the wall above the pole supporting the paper. Run some cord through it that splits off to two lines that then run to binder clips for the two front corners of the seamless. Now every time you want to get the paper out of the way you can just pull it up from beind the roll without having to bother to actually roll it back onto the tube. If you do it neatly then the paper shouldn't crease or tear, but if you are concerned then I'd suggest a thin strip of batten wood or hard plastic across the bottom edge of the seamless and then clipping to this. A simple $10 solution.
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