Noise During Masking Change

[Harry Smolin]

I observed today in our largest auditorium that the bars appear to be making a loud hammer-like noise as they move during a masking change. Strangely, this noise only happens when the masking is changed from scope to flat and not from flat to scope. What would be causing this and is it something to be concerned about?

[Leo Enticknap]

It is almost certainly caused by a mechanical problem of some description. My guess would be that when moving from scope to flat, a counterweight is being pulled upwards, and that maybe the pulley motor is struggling and meeting resistance; whereas from flat to scope the counterweight is falling, meaning less pressure on the pain point.

The fix could be as simple as a lube job or retensioning some cables, but the worst case scenario if you ignore it could be along the lines of a steel cable breaking and whiplashing through the screen. If you don't feel confident troubleshooting yourself, my suggestion would be to schedule a service call with a firm of riggers that specializes in screens, masking, and curtains.

[Jim Cassedy]

While it's probably something mechanical, like Leo says it's a little trick to tell from the way
you described it in your post. (Unless I'm just really dense, which even my best friends would
tell you is definitely a possibility at times)

Do you have both horizontal (side) and vertical (top) movable masking, like I have at my
present venue, or does just the side OR the top masking move when changing formats?
I've worked at theaters that had 'common width' screens, which meant that the image on
screen was the same width for SCOPE & FLAT so only the top/bottom masking moved,
and I've worked at other theaters which had "common height' screens, where the FLAT
and SCOPE image was the same height, but the SCOPE was wider, which I think is the
way God, and 20th Century Fox intended it to be.
I have had maskings with 'counterweight clunk', as Leo suggested, buy the most common
problem I've had with masking and screens was usually just one of the pulley shafts that
needed a couple of drops of oil. That fix is easy, unless the squeaky wheel is waaaay up
near the top of your stage or proscenium.

[Leo Enticknap]

IMHO, screens with masking on all four sides are good for arthouse venues that regularly show everything from 1.19 Movietone to 2.75 Super Panavision 70. If you try to do this with a common height screen, narrower ratios than 1.85 look tiny. Good point, though: if there are two separate motor and pulley systems behind the screen, step 1 is to figure out which one of them is complaining.

Totally agreed on regular lubrication. I've always found that garage door lube works well, and the cans with a built-in straw nozzle enable you to put the lube where you want it and not where you don't.

[Ryan Gallagher]

Locating the source of the mechanical noise will no doubt be easiest with a friend unless you have masking control via VNC or remote near the screen etc?

But definitely something to address sooner rather than later, unless you identify it and rule it as harmless. Slightly less serious than screen damage, you could end up stuck in some in between format, with no easy way to compensate and have it not look stupid until it is repaired.