Main Curtain Traveller Track vs. Fire Curtain Lattice work: FIGHT!

[Chris Chapman]

History on this one: Back in the day when this facility was being built it was about $3 million over budget. The consultants "wisely" shrunk the building to save money, but did not change any of the lineset spacing or what was to be hung where. Lineset 1 was Valance, 2 was Main, 3 E1, etc. A folding orchestra shell is in place. With the original design intent, it is impossible to close the main in front of the deployed shell. Answer: Swap Valance with Main and success. Success for 15 years. Jump ahead to this week when we replaced all of our rags for fire code compliance. We shifted from 25 oz. natural fibers to 20 oz. synthetics. NOW what happens is as the main flies in at speed, and clears the proscenium, it encounters air flow draw from the house, and ever so slightly drifts downstage as it comes in. Problem #1, the draw is significant enough that the traveller track now impacts the lattice work of the fire curtain arbor. At rest, the track has literally the thickness of my hand (3/4 of an inch?) clearance.

What is a good approach to solving this problem?

We could cut out the offending lattice work... (Bad idea)

We could install a guide wire that draws the offstage end of the main slightly upstage as it flies? This could enduce a twist into the lineset which could eventually be more problematic. (Dirty solution.)

We could rehang the curtains back to the original design with the Main on #2 and not fly with our orchestra shell in anymore. (Ugly solution.)

See attached pics and comment away...

 

[kicknargel]

If what changed was the weight of the curtain, maybe that's where to fix it. Could you add weight (perhaps a bottom chain) to the goods?

I'm not totally clear on what the "lattice work" is, but if the problem is the track bumping something as it flies, could you add some kind of bumper so it's not damaging anything?

 

[Sony]

Do you have access to your grid and the associated sheaves? I assume you don't use lineset #2 now since the Valence is behind the main curtain. If you know what you are doing and you have enough space you could kick the sheaves on lineset #1 an inch or two back, giving you a little more clearance. If you don't know how to properly do this, or don't have safe access then DON'T DO IT! You need to make sure you keep proper fleet angles as well as proper alignment...if you don't know how to do this then this is something you shouldn't try. However if all you need is an inch or two, you may be able to adjust the lineset just slightly upstage to gain the clearance you need. Again...if you have no idea what you are doing DO NOT ATTEMPT THIS you could seriously screw up your system and hurt someone if you do not do this properly. Call an experienced rigger, I'm sure there are experienced companies in your area that could do this work.

Kicknargel's suggestion is also a good one, you could create some type of scenery bumper that guides the pipe past the lattice. This would be the better solution if you don't know how to adjust your lineset spacing. Something like a strip of thin 1/4" Luan or plywood that goes vertically down the front of the lattice. You would need to however attach this in a way that doesn't interfere with the operation of your firecurtain.

 

[Footer]

There are several options here... Mpowers will probably have the right one... but...

• Put a bumper on the fire curtain arbor track
• Have the bottom of the curtain weighted heaver, lead tape is usually good for this
• Put guide wires on the pipe. These two cables attached to the deck and grid and UHMW guides ride on the wire and are attached to the ends of the pipe. They keep the pipe from guiding off course.
• A heavy backer can be sewn on the back of the rag which will help it from billowing.

My main rag has the guide wires which really does help. Odds are a combination of all of these things will be the answer. Do you have any issue with the bottom of the rag catching on the top of the shell?

 

[Chris Chapman]

There are several options here... Mpowers will probably have the right one... but...

• Put a bumper on the fire curtain arbor track
• Have the bottom of the curtain weighted heaver, lead tape is usually good for this
• Put guide wires on the pipe. These two cables attached to the deck and grid and UHMW guides ride on the wire and are attached to the ends of the pipe. They keep the pipe from guiding off course.
• A heavy backer can be sewn on the back of the rag which will help it from billowing.

My main rag has the guide wires which really does help. Odds are a combination of all of these things will be the answer. Do you have any issue with the bottom of the rag catching on the top of the shell?

The in position of the shell is below the out position on the main, and it is below the in position of the track as well. The shell has a sweet spot trim that is perfect. So that's not an issue.

The bumper on the fire curtain arbor track isn't an option due to access and allowing a clean run of the arbor.

Footer, can you shoot me a pic of the UHMW guides you are using?

Kicking the lift blocks upstage on the grid isn't an option due to spacing as well. Linesets 1 & 2 would be closer than 6" to each other, and if 2 crept upstage as well, then I'm too close to my first electric.

 

[MPowers]

This is really quick and off the top of my head, so bear with me if it sounds strange (it's late and I've had a loooong hard day - working on a good stiff adult beverage!) Because of the very tight tolerances, the best solution would, at first thought, be a captive guide, i.e. "like" a track. If I understand correctly, the spacing and positions of the various elements in this mix would allow it to work, IF, the moving element did not drift in either direction while in motion. Is this correct? Think about a guide rail that is beside the lattice guide, not between the guide and the traveler track.It does not have to protrude past the lattice at all. Think about a guide rail, offset from the rear of the proscenium in a similar manner to the knee braces that hold the "T" bar guides for the arbors away from the side wall. The guide rail would, perhaps, (lots of room for different ideas here) be a single "T" and the guide shoe mounted to the track would close around the single "T" instead of between two "T's" like the arbor shoes. Probably have to have bit of vertical height to the shoe mounted to the track it prevent grabbing and tilting. Probably need to track both ends to get a smooth travel without oscillation on the opposite side if it were free.

There are a lot of design issues to work out. Does the track follow all the way to the ground if the batten needs to lower to floor working height or does it disengage at some point and need to be guided back in as the batten is raised? What is the budget for the "cure"? Is there a time frame when the stage is dark long enough for the work to be done. Would the track work better on the side of the lattice arbor or at the ends of the batten or braced off the rear of the proscenium? Is a guide needed on both sides? Is there a height which the batten would never be raised past on the up end of travel?

Bottom line, some sort of guide seems to be in order. However there may be other solutions. Getting a skilled rigger on site to assess the situation and propose solutions is the only real answer. Maybe it is as simple as adding a 3/4" thick, 2" wide strip of UHMW on edge to the outside of the onstage side of the lattice track, protruding only 1/4" to 1/2" beyond the track to simply act as a rub bar, allowing the track to simply slide up and down right where it normally would without the influence of the "wind effect". As mentioned before, there might need to be a similar rub bar installed on the opposite side of the stage to keep the batten parallel to the plaster line. Hmmmm, the more I think about it the more a rub bar sounds like a possible solution. Just thinkin'. A rub bar could extend pas the lower edge of the lattice track a few inches and with a slight angle or roll-off, would allow the track to glide past if bringing it to the ground and would not need anything attached to the floor.

Anyway, hope these quick thoughts help you to find a solution, whether mine or not. At any rate, keep us up to date on the problem and what trials and tribulations you go through to reach a solution. This is an interesting problem.

 

[derekleffew]

... I'm not totally clear on what the "lattice work" is, ...

Rather than a T-Track where the counterweight s are perpendicular to the wall, a lattice track (usually used for the fire curtain if full-height flyspace and sometimes for the main rag) has the weights parallel and just a short distance away from the back of the proscenium wall. Thus lots of track support brackets upon which to foul.

There are several options here...

• Put guide wires on the pipe. These two cables attached to the deck and grid and UHMW guides ride on the wire and are attached to the ends of the pipe. They keep the pipe from guiding off course.

I think I like this solution the best--guide cables running from grid to deck, but would add to make the bottom attachment removeable (possibly a shackle into a threaded eyebolt, or something like a floor block socket plate) so the vertical guide wire ropes (one each end of batten) can be temporarily removed when not needed and in the way, at least at the bottom. You may also need rings on the offstage edges of the goods. I saw a Tiffin installation like this years ago. Now that I think of it, the main in that case was built as an elaborate framed drop. I might be thinking of the Ohio Theatre, part of Cleveland's Playhouse Square.

 

[Footer]

I think I like this solution the best--guide cables running from grid to deck, but would add to make the bottom attachment removeable (possibly a shackle into a threaded eyebolt, or something like a floor block socket plate) so the vertical guide wire ropes (one each end of batten) can be temporarily removed when not needed and in the way, at least at the bottom. You may also need rings on the offstage edges of the goods. I saw a Tiffin installation like this years ago. Now that I think of it, the main in that case was built as an elaborate framed drop. I might be thinking of the Ohio Theatre, part of Cleveland's Playhouse Square.

My main rag is a Tiffin rig, it actually used to be automated way back when... traction block is still up there. I'll take a few shots, it works rather well. We are on 6" centers so things can get rather tight.

 

[MPowers]

So, why is it no longer automated? How is it operated now?

 

[Footer]

So, why is it no longer automated? How is it operated now?

It is a standard v groove head block with a purchase line and all that gack. There is a motor and clutch connected ton the head block. To control the rag you had a speed knob and up down... that is it. Top and bottom limits only. This system was disconnected way before my time. Right now the clutch is disengaged and we operate it like any other line.



Sent from my Galaxy Nexus using Tapatalk 2

 

[Malabaristo]

I think I like this solution the best--guide cables running from grid to deck, but would add to make the bottom attachment removeable (possibly a shackle into a threaded eyebolt, or something like a floor block socket plate) so the vertical guide wire ropes (one each end of batten) can be temporarily removed when not needed and in the way, at least at the bottom.

I'm not sure this would work. If we're talking about a grid high enough to fly out a full-stage drop, then I doubt you'd be able to prevent 3/4" of sway with cable guides. I regularly work in a space with wire-guided arbors on a 60' grid and see way more movement than that.

 

[MPowers]

I'm not sure this would work. If we're talking about a grid high enough to fly out a full-stage drop, then I doubt you'd be able to prevent 3/4" of sway with cable guides. I regularly work in a space with wire-guided arbors on a 60' grid and see way more movement than that.

All the major rigging manufacturers discourage wire guide system over 30', strongly discourage systems over 40' and we have the cleint sign a "Hold No Harm" waiver for wire guide systems over 50'. At that distance a wire guide can do little except prevent the arbor from twisting more than about 90 degrees and the amount of sway is difficult, if not impossible, to limit to less than 6"-8" depending on the strength of the attachment points. and the diameter of the guide line. At those extended lengths, the tension needed to hold a straight line grows at an expotential rate. Even a 3/8" cable at, say, 7,000# of tension would not provide a ridgid guide.

 

[Footer]

The in position of the shell is below the out position on the main, and it is below the in position of the track as well. The shell has a sweet spot trim that is perfect. So that's not an issue.

The bumper on the fire curtain arbor track isn't an option due to access and allowing a clean run of the arbor.

Footer, can you shoot me a pic of the UHMW guides you are using?

Kicking the lift blocks upstage on the grid isn't an option due to spacing as well. Linesets 1 & 2 would be closer than 6" to each other, and if 2 crept upstage as well, then I'm too close to my first electric.

Here ya go:

Keep in mind this was installed in 1978...

 

[MPowers]

.........The bumper on the fire curtain arbor track isn't an option due to access and allowing a clean run of the arbor..........

Chris, I don't think you're picturing a bumper or guide strip the way it would be configured and installed. First, access is not an issue except during installation, and that's not really a problem. Any rigging company that can install the lattice arbor in the first place can easily figure access for a small retro-fit. Second, any bumper or guide strip would be on the outside of the lattice and would not interfere with the arbor travel in any way.

As to that really nice wire guide footer shows, it looks like he has considerably more space to work in than you do. It looks like an ideal solution for his situation. On the other hand, if you have a walking grid, installing a wire guide would be extremely fast, easy and dirt cheap. It could easily be installed by your in-house technicians. So, you could well afford to try that first and then go on to another solution if the guide wire didn't work.