Rotating 4 Panels in Unison

[anomalus]

Hello! I am a budding technical director who has been tasked to attempt to rotate 4 tall (16'-0"x4'-0") portal panels at the same time, spaced evenly apart at 3'-6". They will be tied to the floor with a small "lazy susan" turntable, but i am not sure how to tie it to the portal header above. I assume I need some sort of flange bearings, gears and chains to get them to rotate together, but i'm not sure how to spec them out. Also, any advice as to how to run them off stage and out of sight would be greatly appreciated, or if just pushing on one to move the rest is fine too.

We do not do any automation here so manual is the only option.

Thanks!

 

[robartsd]

Hello! I am a budding technical director who has been tasked to attempt to rotate 4 tall (16'-0"x4'-0") portal panels at the same time, spaced evenly apart at 3'-6".

I'm reading this as 3'6" on center for 6" of overlap when closed; but this could also be interpreted as 3'6" clear when in the "closed" position.

 

[sk8rsdad]

If you choose to use panels then they could be suspended from the portal header with a simple pivot at the bottom, rather than a lazy susan. It could also be done by constructing free-standing periaktoi and using stage crew behind each unit. The periaktoi hides the stagehand.

One method of rotation would be to attach common cordage near the top corners of each panel, one cord per side. Look at a venetian blind for a smaller scale example. a separate armature could be built above the panel if sightlines are an issue. Continue the line out into the wings, one to each side. Pull on a cord to rotate the panels as a unit. More pulleys would allow both cords to be routed to the same wing.

 

[Footer]

Can you weld? Doing this with wood will be nearly impossible if you want it to appear automated. The flats and the header should all be steel framed.

You are looking for a pillow block. They make them that will take 1 1/2" Sch. 40. I would run a piece of schedule 40 the whole height of the flat. That would tie into a block on the deck and a set of blocks on the header. You can them mount your gears to that shaft and chain or wire rope it from there. If they don't have to spend contoniusly you could also build some kind of arm off of each one and run wire rope between. Lots of options here.

 

[robartsd]

One method of rotation would be to attach common cordage near the top corners of each panel, one cord per side. Look at a venetian blind for a smaller scale example. a separate armature could be built above the panel if sightlines are an issue. Continue the line out into the wings, one to each side. Pull on a cord to rotate the panels as a unit. More pulleys would allow both cords to be routed to the same wing.

A cord attached to just one top corner would be sufficient to be able to turn all the panels as long as you have access to pull either end of the cord. With two cords, you could operate it in either direction from either wing by pulling on either the front cord or the back cord or you could have the cords terminate at the far panel.

 

[anomalus]

Can you weld? Doing this with wood will be nearly impossible if you want it to appear automated. The flats and the header should all be steel framed.

You are looking for a pillow block. They make them that will take 1 1/2" Sch. 40. I would run a piece of schedule 40 the whole height of the flat. That would tie into a block on the deck and a set of blocks on the header. You can them mount your gears to that shaft and chain or wire rope it from there. If they don't have to spend contoniusly you could also build some kind of arm off of each one and run wire rope between. Lots of options here.

Thanks for the info! Unfortunately, i've been trying to get a welder for here, but it is not within the budget at the moment. I could possibly swing by a place around the corner to help weld some items. Would I weld the gears to the sch.40?

 

[anomalus]

If you choose to use panels then they could be suspended from the portal header with a simple pivot at the bottom, rather than a lazy susan. It could also be done by constructing free-standing periaktoi and using stage crew behind each unit. The periaktoi hides the stagehand.

One method of rotation would be to attach common cordage near the top corners of each panel, one cord per side. Look at a venetian blind for a smaller scale example. a separate armature could be built above the panel if sightlines are an issue. Continue the line out into the wings, one to each side. Pull on a cord to rotate the panels as a unit. More pulleys would allow both cords to be routed to the same wing.

The director and designer wants these units to move by 1 person, we do not have a stage crew, sadly, it is all done by 1 intern on deck.

 

[kicknargel]

I agree there are many way to get the skin off this feline. IMHO, the pipe/shaft and pillow block/bearing idea is good, but could be done cheaper. The bearings and sprockets/pulleys for the 1.5" sch.40 will be expensive. You could use your lazy susan at the bottom, and attach a small length of shaft at the top of each flat, extending up through bearings attached to your portal header (assuming it's structurally sound). You could then put sprockets and roller chain, or lever arms, or whatever onto the shaft. Nice thing about using actual shaft is you can used keyed attachments.

Poke around the power transmission section of McMaster-Carr for ideas.
http://www.mcmaster.com/#power-transmission/=wb3hoj

 

[anomalus]

I agree there are many way to get the skin off this feline. IMHO, the pipe/shaft and pillow block/bearing idea is good, but could be done cheaper. The bearings and sprockets/pulleys for the 1.5" sch.40 will be expensive. You could use your lazy susan at the bottom, and attach a small length of shaft at the top of each flat, extending up through bearings attached to your portal header (assuming it's structurally sound). You could then put sprockets and roller chain, or lever arms, or whatever onto the shaft. Nice thing about using actual shaft is you can used keyed attachments.

Poke around the power transmission section of McMaster-Carr for ideas.
http://www.mcmaster.com/#power-transmission/=wb3hoj

Awesome, I was looking around there and let me know if this sounds like it would work or not. If i were to use the lazy susan for the bottom, for the top, I use a 1/2" flange bearing, use a 1/2" shaft, slide a shaft collar in place, slide a sprocket in place, slide another collar in place (idea is to secure the sprocket this way because we can't weld here, possible?), then secure the other end of the shaft with a locking flange. Do this for all the panels, then connect them with a drive train from sprocket to sprocket. Spin one panel and the rest should spin evenly with. Sound bout right? Thanks for all the suggestions! Much appreciated!

 

[Robert]

I did Chorus Line and used 6 double sided flats 4 x 12. One side was mirror and the other black velour. We built the flats Hollywood style and had a pivot point on the bottom with roller bearings on each outside of the bottom rail. On the top we attached roto-drapers to a batten and that handled the rotation and carried the load. To turn them we made a long stiffener that ran along the floor behind the flats and attached with a small mending plate to one edge. The mending plate was attached with bolts and left loose so it could rotate easily. The offstage side of the long stiffener had a handle and with a little effort we were able to rotate all the flats at once.

 

[anomalus]

I did Chorus Line and used 6 double sided flats 4 x 12. One side was mirror and the other black velour. We built the flats Hollywood style and had a pivot point on the bottom with roller bearings on each outside of the bottom rail. On the top we attached roto-drapers to a batten and that handled the rotation and carried the load. To turn them we made a long stiffener that ran along the floor behind the flats and attached with a small mending plate to one edge. The mending plate was attached with bolts and left loose so it could rotate easily. The offstage side of the long stiffener had a handle and with a little effort we were able to rotate all the flats at once.

Unfortunately, we are in a small space with no pockets so having rigging on the stage is a no-go since they use the openings between panels as entrances and exits. Any way to rig that above? Thanks for this info though!

 

[Robert]

I think we choose the floor operation since the panels were more secure at the floor level. I think if you try to control them from the top you will need to anchor the battens to keep them from swaying when you rotate them. Probably need to do that with any system you come up with that is rotating the panels from a top position.

 

[Traitor800]

Awesome, I was looking around there and let me know if this sounds like it would work or not. If i were to use the lazy susan for the bottom, for the top, I use a 1/2" flange bearing, use a 1/2" shaft, slide a shaft collar in place, slide a sprocket in place, slide another collar in place (idea is to secure the sprocket this way because we can't weld here, possible?), then secure the other end of the shaft with a locking flange. Do this for all the panels, then connect them with a drive train from sprocket to sprocket. Spin one panel and the rest should spin evenly with. Sound bout right? Thanks for all the suggestions! Much appreciated!

Dont forget some sort of chain tensioner. You might even want a tensioner between each flat to make the system more responsive. Also cause your sprockets are horizontal your going to need some sort of support between sprockets to keep the chain level so that it doesn't walk off of the sprockets. And whatever you do don't forget to order a chain break tool.

 

[Thom P]

Belated, but hey. The problem never goes away, does it?
Because our theater has no fly gallery, I used three periaktoi in lieu of drops for "You're a Good Man, Charlie Brown" and the desire was for them to rotate together. The cues were tight so we had to rotate full 360° ...
Periaktoi were 4'x10' flats (1/8 luan on 1x pine frames, supported on 3/4" plywood triangles top and bottom. Base pivot is 1" pipe secured to floor flange, through UHMW (plastic cutting board) bushing on bottom triangle. Top pivot is 1" pipe through 2x strongback secured to building ceiling, also UHMW bushing.
Drive mechanism design was bicycle chain rings and 1/4" roller chain. Chain rings mounted to top of periaktoi, chain tensioners, support rack, to be operated by capstan in the wings. Pretty neat, huh?

Except:
We had no good way to secure the chain rings to the periaktoi. Bicycle chain rings are cheap, but (ahem) too damn thin. Used up a few pounds of screws, bolts, and all sorts of four-letter words and STILL the things wouldn't turn. Well, not consistently. Problem was the rings pulled out of alignment, and the chain flopped around on the thin chain rings. Engineering flaw: a 7"-diameter ring on a 48"-diameter periaktoi is a 1:6 lever arm. LOTS of torque. With opening night four days away, we gave up. Had a half-brain-dead stage hand turn the damn things one at a time. It worked, but it wasn't "elegant" ... sigh.

The fix? Dunno. I like the cable around big plywood disk (above), and actually considered something similar, but that precludes full 360°infinite rotation. Welding in our shop is not an option...we'd have had to --- well, chain rings are just too little for the design. Anyone know of a source for inexpensive 24"-diameter sprockets for #41 chain?

The lesson: Plan (and test) such a system LONG before the two-week window for building a set!

 

[BillConnerFASTC]

For easy and cheap, probably can pivot on a "pin" in a hardwood or metal "cup". The top could just be another pin through a board. Just keep contact areas small, and getting it balanced will be your best friend.

To tie it together, consider a rigid member - a 1x3 perhaps - pinned to top corner of each. Move one and they all move together. You might attach a line to each end and move from off stage. Did a lot of shutters like this - two occasions - with lots of lines to an operator under the set.

 

[Thom P]

... To tie it together, consider a rigid member - a 1x3 perhaps - pinned to top corner of each. Move one and they all move together. You might attach a line to each end and move from off stage. Did a lot of shutters like this - two occasions - with lots of lines to an operator under the set.

These methods certainly work ... as long as there is no need to continue turning the panels (or periaktoi) past 180 degrees. At some point the stick runs into the pivot axle. Or the line moves past the point of pulling, and another line is required to pull the assembly back. The lesson I learned from my recent periaktoi attempt is that light-duty mechanisms are probably going to fail. The effort it took to move one 4'-4'-4' x 10' periaktos by pushing or pulling on one of the corners was small. But then the force was applied near the axle, the force required increased by five or six times.

As an aside, I've built small periaktoi that were supported ONLY on the axle (such as you you suggest) and they worked fine. As long as there is no need to operate them all at once. These big ones, I supported on ball-bearing heavy duty fixed casters (caster axles on the radius of rotation). Really the only impediment to moving them was the random gob of gaff tape or wayward screw.

 

[BillConnerFASTC]

I did think these were more like flats than periaktoi, and overlapped so not 180.