# Another Large Revolve on a Budget



## scrogers (Dec 9, 2015)

Hey all,

First, big thanks to all those out there who help post on these forums for all things tech theatre. CB has been an invaluable resource to me for years, and now looking for a little guidance...

I'm looking to build a 24ft turntable/revolve and I have experience building a couple different versions of a turntable, but am intrigued by a design I've recently come across.

http://theaterdad.blogspot.com/2011/06/how-to-make-revolving-stage.html

Before I found the above link, I was essentially planning for this sort of design. Two layers of ply oriented 90 degrees from each other to form the disk over a bed of casters on the floor in concentric circles. I'd love some input on a few things from this "theaterdad" method.

1- The above method is designed around a 16ft revolve, but, think it would essentially "scale up" to 24ft?

2- Theaterdad used two layers of 1/2in ply, and was all about keeping it light. I too am concerned about weight, for reasons mentioned next. I was planning to go 5/8in since mine will be larger. That said, it seems like eveyone does 3/4, but I'd love the weight savings of 1/2 or 5/8th. Thoughts?

3- What I really liked... was his manual operation method. The "cog rope cup" as he describes, basically takes a knotted rope and loops it around the edge of the disk, and catches on several "cogs" or grooved 2x4's (see his description). I really like this idea because- a) it's relatively inexpensive, b) appears rather simple, and c) is operable from off-stage, BUT, would it scale up to a 24ft table? Rope suggestions? Any huge risks?

4- I'm planning for rings of casters at 3', 6', 8'8", and 11'4" from the center. My questions is, if I use the commonly used pivot method described all over CB of two pipes with flanges set within each other with grease, will the center of the disk have enough support? I have used a car hub and bearing assembly before as well as a slightly different take on the sleeved pivot, but the sleeve doesn't provide any support (vs say a car hub). No one has had issues with not enough central support? I'm just worried with a central ring of 3ft of center (so 6ft diameter) from center and 5/8in ply. 

Basically, I really wanted to go full automation for this show, but after pricing our everything from rentals, to construction etc, motorized automation is just out of the cards for us this show. That said, again, this rope method looks slick... but will it just be impossible to move a 24ft table, let alone how about when I get a thousand pounds of scenery on it, and 20-30 people(?). The blog mentions how easy it was for "a 16 year old girl" to spin the empty table at ridiculous speeds, and still no issues for a strong person when loaded up... I just worry I do all this... and then cannot move it...

Again, thank you all in advance for any thoughts, but just trying to get some experiences or input on the above ideas before I'm deep into a design that's potentially problematic from the beginning.


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## BillConnerFASTC (Dec 10, 2015)

psychlorama" e the time to touch all the details but yes you can build a manually powered 24' turntable. I did 40 years ago for a summer theatre and it worked all summer - maybe 40 performances. It was wire rope and a shop built (wood) hand winch.

The support - at center and elsewhere - is about span. Your span between supports across center is 6' but 3' or less further out. Rethink caster spacing. Add another ring and use double or triple ply and skip the framing. (Think about cutting middle layer of 3 enough smaller so it firms a groove for running line.) And I'd use fixed, not swivel casters, for sure. 

And I have difficulty taking scenery advice from someone who uses the non-word "psychlorama" for a flat drop - just so many things wrong with that.


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## scrogers (Dec 10, 2015)

Bill,

Thanks for the reply!

Yeah... admittedly, I too was cringing a little to the cyc (and a few other) references...

About 15 years ago, I was involved in the construction (but not design) of a 16ft turntable similar to what you're describing, but we used 1/4in braided cable and a manual/hand winch (that we all called "the coffee grinder") to spin the revolve. It was a 3-layer sandwich design with the center layer/disk smaller to allow for a groove for the cable. The final product looked good in theory, but ultimately was incredibly heavy. The issue was we found the cable had to be under such high tension to make the table move reliably (and not slip) that we ran into all sorts of issues (cable stretch, splicing breaks, resplicing, super beefy tensioners.. etc). This also meant the pivot point needed to be quite sturdy.

Mostly, I liked the idea of these "cups/cogs" and a knotted rope, because it appears to allow for a relatively reliable (and slip free) method of spinning a table, without creating a central groove with a 3rd layer of ply (which adds cost and weight). The table is relying on the knots and cogs rather than tension around the disk. I worry that using rope or cable in the central grove method will land me back with the slipping issues(?).

Yes, thanks for the recommendation about casters. After posting last night, and doing some more reading and discussing... I think at least another circle of casters is needed, and trying to get the gaps down to more like 2ft rather than 3ft between each. I'd also plan for all non-swivel casters. I actually currently have a bunch of rather nice ones purchased for the project 15 years ago, I just need to get more. I also totally agree with what others have said, buy the nicest caster you possibly can. They TOTALLY make a difference.

I would plan to use two layers (not 1) of 5/8in ply with the seams at 90 degrees. I feel like that's a decent blend of weight savings and strength. 

I do wish I could find someone else who's thought of, or used that rope knot cog method because again, it seems pretty solid in theory, but theories are just that.

Thanks again for any other thoughts!


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## BillConnerFASTC (Dec 10, 2015)

I should clarify that in my reference the wire rope was attached and wound several times around revolve - so you could only go so many turns one way before having to reverse. It worked for the two (of four IIRC) shows in rep. Avoids slip problem. I think I had a tensioning device - like two pulleys with a tourniquet between them.


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## microstar (Dec 11, 2015)

Research air casters. One source: www.aerogo.com
52 ton tank on an air caster revolve:


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## scrogers (Dec 15, 2015)

While the revolving tank looks pretty epic, I think the air casters are a little out of our budget at the moment.

Putting the drive mechanism aside for a moment- I'll admit I'm having a hard time settling on a final table design. I had initially been thinking two layers of 5/8 ply cut into a circle, then simply laid on top of each other with the seams at 90 degrees, and screwed together. I have actually seen this method done (with 3/4 ply though) and had a recommendation of this since it's rather straightforward, light, and will breakdown back into 4x8 sheets (or less with the edges).

Recently, I've gotten another recommendation of making stretch skin platform pie wedges, which I understand would be stronger in terms of "flex," however, I think I'd need thicker ply, and lots more of it (not to mention 5/4) to make this work. I feel like this will ultimately add more weight (and cost) since it's now essentially the same design as two layers of ply, but with 5/4 framing in the middle (cut into wedges etc). Not to mention design complexity and I'm building a 24ft revolve, so it'll be a lot of pie wedges if I want to try and keep it out of single sheets of ply.

I have done considerable reading here and elsewhere and see the sandwich method (three layers, pie wedge, interlocking), the "Yale method," as well the stretch skin/framed method (mentioned above). I guess, if I get decent quality ply (BC or better) and simply lay two layers of 5/8 together with 80+ casters (on the floor facing up) every 2ft or less... am I setting myself up for issues?

Thanks again... just feeling a little stuck...


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## robartsd (Dec 15, 2015)

If by "strectch skin" you mean "stressed skin" I think that would be a lot of work for little gain unless you are planning on using this revolve a lot. Stressed skin panels are efficient for lengthening spans while minimizing thickness, but that does not seem to be the problem you are trying to solve.


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## microstar (Dec 15, 2015)

I think your problems will occur not with the turntable empty but trying to turn it with the load you describe. That is why I brought up air casters, because the whole thing becomes frictionless when it is supported by the "air cushion".

The air casters I used over 40 years ago while in graduate school were the 8" AeroGo model, which was basically a vinyl or neoprene "doughnut" with an air inlet fitting. These were basically just "replacement" casters and not complete pallet assemblies. We used four of them on a large wagon that carried a set up and down a raked stage. There was a steel guide fin that rode in a slot in the rake, and a loop of rope was attached to each end of the fin and around floor-mounted pulleys at the upstage and downstage ends under the rake. One stage-hand sitting under the upstage end of the rake moved the wagon. He had to be careful because if he released the rope, the wagon would glide down the rake and crash into the orchestra pit!

As I recall (40 years ago) the air casters were quite inexpensive as they were just a vinyl/neoprene doughnut with a masonite landing pad /mounting block in the middle. The real trick was supplying enough air at low pressure and high volume, because it's the escaping air that "floats" the load. It was probably 20-25 PSI at maybe 10-15 CFM per caster. One of the shop staff had the bright idea to get an emission-control pump (remember this was the 1970's!) from a salvage yard and hook it up to a high horsepower electric motor (borrowed from the theatre's HVAC system) because under the hood it was driven off the car engine. It supplied the necessary low pressure/high volume air but was so noisy it had to be located in the basement under the stage with a large air hose coming up to the wagon.

The air casters typically lift a wagon about 3/4" off the deck and if the wagon framing is not rigid, there can be issues.
The smoother the floor, the less air loss as well. The only noise is the hiss of escaping air, and not the rumble of casters.

You will find it a fascinating experience should you decide to go this route. All of the air caster manufacturers have applications engineers who can offer advice for using their products and could suggest ways to supply the necessary air volume. Renting some kind of blower to supply the requisite pressure/volume is another possibility. I wouldn't be too quick to dismiss the air caster solution.

Here is another website: http://www.solvinginc.com/air_film_technology.htm[/QUOTE]


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## scrogers (Dec 15, 2015)

Haha... yes, thanks robartsd, I most certainly meant stressed skin (rather than stretched), platform wedges.

Yeah, I don't really care much about the thickness, but do care about the strength. I feel that two layers of sandwiched 5/8 BC ply sheets (seams at 90 degrees) will be plenty strong, but I acknowledge the risk (or more of a risk) of warping vs building the stressed skin wedges or platforms. That said, if the ply is badly warped to begin with, even a stressed skin platform won't help (the way I see it).

Thanks for this, I think I am leaning back toward two large 5/8 ply disks sandwiched... I know there are some assembly challenges as I'll basically have to lay it all out and then screw together on top of the caster bed... but, the construction and design feels more straightforward than some other options...


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## BillConnerFASTC (Dec 15, 2015)

Whether double 5/8 is strong enough is a function of the span between casters. 

Stressed skin does not require thick ply. Can do with as thin as 1/8" but easier to work with 1/4 or 3/8. Depending on core - 5/4 or other lumber or foam - it is more labor intensive but much lighter and can be thinner of similar spans.

Aircasters are great, if the noise is not a problem (farting us how some describe it) but must be higher cost.

A lot of analysis for structure and casters to find most efficient combination.

Keep in mind double 5/8 is half as strong as single 1 1/4 ply. I'd need to calculate but pretty sure 1/2 and 3/4 us stronger than double 5/8.


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## JChenault (Dec 15, 2015)

Bill

Can you clarify for me why a 1/2 +3/4 would be stiffer than two 5/8. I'm not understanding the physics. ( assuming they have a solid connection between the sheets )


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## scrogers (Dec 15, 2015)

Thanks again for the replies.

I spent a little more time looking at air casters. While I don't have exact figures, the basic casters do appear pretty simple, but I think the costs associated with the extra equipment etc needed to run/operate the caster still makes it a bit of a reach for us over a fixed caster. Additionally, I agree with Bill that at least in all the videos I've now watched with them, the hiss or "fart" produced by the caster ranges from a "slight noise" to quite a noticeable sound. I think it'd be an issue for some of my directors.

The stressed skin recommendation to me was 1/2in ply and 5/4 frame 2ft on center (~1'10" spans). I questioned that much of a span with 1/2in ply (since that leaves a nearly 2ft area of 1/2in ply unsupported), but then also read elsewhere the "gaps" could be filled with foam, or basically remove the interior 5/4 framing all together and use foam. That does seem strong (if foam filled) but I also question the weight. Does seem to make sense though if solid foam and thin skins. That said, I also agree with Bill that the stressed skins are more labor intensive, and I'm still not sure it's worth it for my project. I have no intention of ditching my ply/table when I'm done, but I think the individual ply discs will store better as 4x8 (or smaller) sheets than 8-9ft stressed skin pie wedges.

As for casters, I have 90 rather nice Bleutec (now Blickle) 4in rigid/fixed casters. Some are a older than others, but they are really pretty unbelievable how smooth and quiet they are. So, I've upped my casters from my initial design/post and am planning for rings at 1', 2', 4', 6', 8', 10', and 11' 4". This brings the spans as low as about a foot, up to about 2ft between casters in any direction.

I have only worked with 1 1/4 ply once (or it was something close to that, might have been 1 1/8 or something) as it's pretty hard to source (and expensive) in my experience, but it is pretty awesome stuff. Very rigid, but also crazy heavy. I'm not wedded to two layers of 5/8, especially if 3/4 and 1/2 are stronger, but from my calculations, they are basically the same weight, but unsure about "strength"(?).

Thanks again for the guidance.


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## BillConnerFASTC (Dec 15, 2015)

I think you're on the right track.


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## robartsd (Dec 17, 2015)

90 casters is only about 1 per 5 square feet, so you'll need some more for that much area.


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## scrogers (Dec 18, 2015)

Robartsd,

Thanks for the reply. Just wondering your (or others') recommendation? In my initial plan/post here, I was certainly low on casters (more like 60). That admittedly left some gaps well over 3ft (not including the center span which was huge). After talking with others (and recommendations here), it was suggested to be more like 80+ casters, so I increased the number of rings and upped it to 90. With the rings in the above mentioned positions (2 posts up), I think that leaves a maximum gap of 2ft-ish (or just over) with some even less.

I can get more... but just trying to get a sense if I'm "a few short" or like another 20-30 short... (for cost... sorta hoping closer to the first option than the second.)

Thanks!


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## robartsd (Dec 18, 2015)

Here's my thinking on estmating how many casters you need:

A 24 foot diameter circle is 452.4 sqare feet. 2 feet by 2 feet is 4 square feet (if more than 2 feet between rings is too much, more than 2 feet between casters in a ring is too much). 452.4 square feet divided by 4 square feet is 113 casters (I'd probably round that estimate up to 120 since you aren't laying them out on a grid). So it looks like 20-30 short is more like it. That is unless you're building a frame over the casters to support the deck - but my impression is that the deck will be two layers of plywood supported directly by the casters.


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## scrogers (Dec 18, 2015)

robartsd said:


> Here's my thinking on estmating how many casters you need:
> 
> A 24 foot diameter circle is 452.4 sqare feet. 2 feet by 2 feet is 4 square feet (if more than 2 feet between rings is too much, more than 2 feet between casters in a ring is too much). 452.4 square feet divided by 4 square feet is 113 casters (I'd probably round that estimate up to 120 since you aren't laying them out on a grid). So it looks like 20-30 short is more like it. That is unless you're building a frame over the casters to support the deck - but my impression is that the deck will be two layers of plywood supported directly by the casters.



Yeah, as you've probably seen from the above posts, I was leaning back toward two 5/8in ply disks with seams at 90 degrees, rather than stressed skin or framed wedges/platforms. So, the casters would directly support the two layers of ply. 

While I think the actual point-to-point distance between casters for much of the table would be at or around 2ft, your math/logic is solid (and doesn't lie). To get all spans below 2ft, I need more like 110-120 casters or "points." I haven't had time to redraw out all my caster points in CAD from my initial (way under speced) design, so I need to sit down and do that... then I can feel more confident.

Makes sense though that with two layers of 5/8 (unframed), I really need to get all/ever spans below 2ft... Thanks... off to reevaluate some math...


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## BillConnerFASTC (Dec 18, 2015)

if doing casters up , lay some out and lay two sheets of ply on them and (very carefully) walk and jump around on the ply and see if 24" or 28" or whatever will be good enough. You'd really like to cut one sheet in half so grain is opposite and you can see the effect of a seam. Nothing like empirical testing.


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## scrogers (Dec 18, 2015)

Yeah, a little real-world mockup is a great idea. Unfortunately, I don't stock much 5/8in ply, but I may still give it a shot.

I still haven't placed them out in CAD yet, but I have run some more math, and... yeah... well, to get the arc distances below 2ft between them on the circle will require quite a few more casters. Here's what I'm seeing:

Ring Rad - Circumference - # of Casters - Distance Apart

1’ - 6.28ft - 4 casters @ 1.57ft
2’ - 12.57ft - 7 casters @ 1.79ft
4’ - 25.13ft - 13 casters @ 1.93ft
6’ - 37.7ft - 19 casters @ 1.98ft
8’ - 50.27ft - 26 casters @ 1.93ft
10’ - 62.83ft - 32 casters @ 1.96ft
11’4” - 71.19ft - 36 casters @ 1.97ft
Total - 137 casters

That is quite a bit more than 90...

Unfortunately, between these caster increases and the need for good quality ply as my bottom "rolling" layer, costs are getting up there. I won't cheap-out on casters either since I know how much of a difference good ones make.

Going to need to come up with a rather cost effective manual drive system for this thing...


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## robartsd (Dec 18, 2015)

The first place I'd look to save money on this project would be reducing the size of the turntable - more than 25% of your casters are in the outermost ring - but I don't know how the decision that this needs to be 24 foot diameter was made.


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## scrogers (Dec 19, 2015)

Yeah, some quick math does demonstrate the possible cost savings by reducing the overall revolve to 20ft. Unfortunately, there are some design decisions that have already gone into action that sorta require the 24ft span to move.

Obviously my costs have increased, but it sorta will be what it is...

As for driving the unit, I'm looking at some decent rope with knots at intervals that will be looped around blocks attached to the edges... and then people to pull... hard. I'm hoping with nearly 140 rather high-quality casters and some strong backs, I can get it to spin with at least some load on it...


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## BillConnerFASTC (Dec 19, 2015)

Look at cost of double 3/4 ply versus more casters. My instinct says that with optimal spacing of 90 casters you'd be fine. I'd star with a ring maybe 10 or 11" from perimeter and maybe an inner ring of 3 casters - guessing that is 27 - 30" diameter. A couple of pieces of umhw supporting center - donuts around the pivot - and inner ring jumps out quite a bit. Lots of CAD fun playing with layouts.

I didn't see caster load rating - do you know? I'd think 4" was up around 300-400 minimum but would have to look. I suspect span will still be limiting factor.


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## scrogers (Dec 19, 2015)

Well... I was starting to consider that as well. So, it looks like it's only about $125ish difference between getting two layers of 5/8 (one disk of AC facing down, one disk of CD facing up), and two layers of 3/4 (same deal, one disk of AC facing down, one disk of CD facing up). The only other reason I had been thinking of 5/8 over 3/4, is weight. By my calculations, two layers of 3/4 will be about ~450lbs more than two layers of 5/8. Since I know I'm going to be driving this thing manually, I was/am trying to keep the table weight down as well... but... maybe it's worth the extra 450lbs for the strength(?).

The Bleutec 4in rigid casters I'm using are rated to "330lbs" each, so I think (hope) I'm ok there...

Years ago when I was involved in constructing (but not designing) a 16ft revolve, I'm sure we only used about 50-ish casters. This thing was the 3-layer "bread-and-cheese-sandwich" method though, and was quite solid... but was REALLY heavy (still have horror stories about trying to load-in and strike the thing safely).

Yeah, after spending some more time with the math and CAD... if only 90 casters are used, there are a number of spans that are certainly over 3ft. I guess another option could be to get a few more casters to bring the total more like 100, and up the layers to 3/4 ply, and then play around with the spacing some more to sorta try and get the best of all worlds(?).

I'm having all sorts of fun playing with the caster layouts in CAD... and looks like there may need to be more.


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## microstar (Dec 19, 2015)

I recently built a 7' diameter turntable with double 3/4" ply disk and 3.5" rigid casters attached to the bottom. A ball-bearing weight-supporting center hub. 3/4" rope spliced in a loop going around 2x4 "spokes" attached to the underside. Idler wheels to keep rope tensioned. About 350 pounds of load plus the turntable weight. Took one medium-sized person a fair amount of effort to rotate 180 degrees each time. It will be interesting to see how much force it will take on a rope to turn your 24' turntable. You might consider a backup plan to the knotted-rope method.


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## scrogers (Dec 19, 2015)

microstar said:


> I recently built a 7' diameter turntable with double 3/4" ply disk and 3.5" rigid casters attached to the bottom. A ball-bearing weight-supporting center hub. 3/4" rope spliced in a loop going around 2x4 "spokes" attached to the underside. Idler wheels to keep rope tensioned. About 350 pounds of load plus the turntable weight. Took one medium-sized person a fair amount of effort to rotate 180 degrees each time. It will be interesting to see how much force it will take on a rope to turn your 24' turntable. You might consider a backup plan to the knotted-rope method.



microstar,

This sounds very similar to the drive system I'm thinking (hoping) to make work on mine. Basically- spliced rope loop with knots, 2x4 blocks (or spokes) on the bottom of the disk, a couple tensioners... and then strong people. You say 3/4" rope, but what type did you end up with? I'm planning to do 4in casters facing up (attached to the floor). I've read about someone making essentially the same thing we're talking about work with a 16ft turntable (made of two layers of 1/2in ply though), and "1/2in rope" but not lots of detail there either. That was described as "easy for a young girl to spin very quickly with no load on the table" and "very manageable for a couple people even with set pieces and 15-20 people." Granted, I'm talking a much bigger disk, and potentially lots of set pieces and people...

I don't know, I'm now leaning more toward dual layers of 3/4 ply for strength, but do worry a bit on how well this "rope method" will scale up. I can easily throw people at the problem though, but, there's only so much room and so hard they can pull in sequence...

I know your table is much smaller than what I'm talking about, but any insight into how that worked out is appreciated. Thanks.


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## BillConnerFASTC (Dec 20, 2015)

How much does it have to turn, as in how many 360 degree rotations until it can go reverse? And how fast do you envision?


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## microstar (Dec 20, 2015)

scrogers said:


> microstar,
> 
> This sounds very similar to the drive system I'm thinking (hoping) to make work on mine. Basically- spliced rope loop with knots, 2x4 blocks (or spokes) on the bottom of the disk, a couple tensioners... and then strong people. You say 3/4" rope, but what type did you end up with? I'm planning to do 4in casters facing up (attached to the floor). I've read about someone making essentially the same thing we're talking about work with a 16ft turntable (made of two layers of 1/2in ply though), and "1/2in rope" but not lots of detail there either. That was described as "easy for a young girl to spin very quickly with no load on the table" and "very manageable for a couple people even with set pieces and 15-20 people." Granted, I'm talking a much bigger disk, and potentially lots of set pieces and people...
> 
> ...



I did not put any knots in the 3/4" natural Manila rope for my 7' turntable because with the small diameter, I figured the rope made sharp enough bends that it wouldn't be necessary, and we encountered no slippage. The idlers had to be strategically placed as well due to legs for the platforming spanning over the turntable unit. I think you will want the knots in yours. To me, one of your big problems (besides the friction of all the casters/getting all the weight moving) would be keeping enough tension on the slack side of the rope as all the pulling happens on the drive side. You also might have to bolt the 2x4 spokes in place as a lot of force will be applied, especially to the first one the rope knot makes contact with as it comes off the turntable. Unlike meshed gears, you really don't know how many knots will actually contact spokes as it's being pulled. The photos are from "The Game's Afoot".


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## dbaxter (Dec 20, 2015)

Well, since we're talking turntables and "The Game's Afoot"... Our 7' turntable is (currently running) made from 3/4 ply with 1x4 radial supports where the casters are mounted. There are 12 six 1/2 high casters. Since this only goes back and forth, I had the luxury of fastening the pull rope at one point. The rotating wall has a pivot at the top to keep it square to its surround. One person can pull it while two people ride. The problem of keeping tension on the non-pulled side was solved by running the rope through a tear-drop shaped scrub brush mounted to the end guide.


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## scrogers (Dec 21, 2015)

Thanks for the replies and sorry for the delay, I've been traveling.

So, as for rotations, the table needs to be able to spin a full rotation in a minute, at minimum. To be honest, I know my directors would like a full rotation in as little as 30 seconds, but they are also (slightly) aware this is likely unreasonable.

It certainly needs one full rotation in either direction, with preferably no restriction on direction or rotations. I've been involved with a revolve using a double-wrapped wire rope cable before, and honestly, the overlap/rotation issues with the cable... were huge.

Thanks so much for the Games Afoot pictures. The idea of the rope attached to the disk also good... but unfortunately not going to work for us with the multiple rotations likely needed.

I'm hopefully going to make tensioners out of boom-bases attached to the floor with short pipes. I actually read a similar description of this and then sliding PVC over the schedule 40 pipe like a pulley. I also agree that I'm going to likely need the knot method so it doesn't slip, and I may need to bolt, rather than screw the spokes/cogs to the disk due to the forces on the knots and blocks.

Unfortunately, I'm out of town and not going to be able to truly mock this up for a bit. I'm CADing this all out as much as I can for now and plan to put this all into action shortly.

Thanks again for any ideas and/or recommendations.


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## lwinters630 (Dec 22, 2015)

scrogers said:


> Hey all,
> 
> First, big thanks to all those out there who help post on these forums for all things tech theatre. CB has been an invaluable resource to me for years, and now looking for a little guidance...
> 
> ...


I am attaching some drawings that I received from Van but his links do not seem to be active, and other sources (can't remember which). I was going to build Les Mis revolve but ended up doing a different layout. I hope these help. Note fixed casters will work best.


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## scrogers (Dec 28, 2015)

Thanks for all the PDFs and images. I had come across these plans before here on CB. While this does help with some numbers of casters etc, I think I have decided to go with the two large disks out of two layers of ply rather than the pie wedge method.

I have finally gotten to spend a lot more time in CAD, and I think I have finally settled on two layers of 3/4in ply (seams at 90 degrees) up from the 5/8in I was thinking. I have also upped the casters from 90 to about 120 (and now nearly double from my first post here). As noted from the posts above, to really get EVERY span below 2ft, the total number of casters is nearly 140, however, with a few adjustments, and allowing some spans to go only a few inches over 2ft, I can get the casters down to just about 120, and still feel very comfortable with the spans (I think the largest span is like 26-27in, and it's only in a few places).

So, I think with two layers of 3/4in ply (one AC one CD), and 120ish casters, this thing will be pretty sturdy.

As for moving the table... there will have to be some trial and error, but I'm planning to attempt this "rope knots and cup" method described here in this post and see where it gets me. Like I said, I can easily throw a couple strong back at this, but I can't really make motorized automation fit into the budget... so manual operation it will be. Hopefully, with the high-quality fixed (not swivel) casters placed regularly, with decent ply, and strong rope (and people) I can get this to move...

Thanks again for all the help and comments, and I always welcome more thoughts and ideas. Actual construction will begin early next week... and hopefully things come together...


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## dbaxter (Dec 28, 2015)

Looking forward to the post-show report.


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## scrogers (Jan 13, 2016)

Post installation update-

Well... The table is in. 122 casters on plates to make them at 7.5in so the final deck height is 9in off the floor. Two layers of 3/4in ply (AC lower CD upper) seams at 90 degrees. The thing is a beast, but from the brief initial testing.... it appears to work pretty well.

Issues? Plenty, mostly around the fact that the ply, while decent quality (and from a good lumber yard), was not PERFECTLY flat (especially the upper CD layer). This meant that every seam basically had to be "sewn" up with 1-1/4in screws every 3-6in throughout the entire table. I knew there would be lots of screws, but honestly, it took thousands to make the bottom smooth, which just took a considerable amount of time. We eventually got the process down using leveling blocks underneath, cut at the correct height, then placed on seams and 4-corner junctions with people standing on the deck while screwing everything together.

The caster assemblies were monotonous to assemble, as was the placement and alignment. The greased-pipe-sleeve-center-pin method seems to work well and most of those processes went according to plan.

Then... the maiden spin was a glorious thing. It is heavy, but one person (just pushing the edge) could easily spin 6-8 people, and two people could get it moving dangerously fast. The hardest part is getting it started while loaded down, but once moving, it doesn't take much to keep it moving and it actually takes quite a lot to get it to stop once moving fast. I have yet to really load it up, but all in due time.

Next big thing (aside from all the other rolling stair units, set pieces, and things that go on the table and set) for the table, is the movement. I am going to attempt the "rope and cup" method mentioned before, done by mounting 6in grooved 2x4 blocks spaced every foot or so with rope threaded through and knots every 3 ft or so spliced into a loop. I'll then make some tensioners and a return loop... and hope.... I'm thinking some nice 1/2in polyester rope since it doesn't have much stretch(?) As always, I welcome any suggestions...

Anyway, thanks again for all the interest, help, and support. I have some pics which I'll try and get up of both the process and mostly final unit... Crossing my fingers on the rope drive, but will also update down the line as that comes together...


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## bobgaggle (Jan 14, 2016)

once you get it going can you post some photos of the drive system? I've heard of the knotted rope method but never seen it in practice...


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## microstar (Jan 14, 2016)

I think I would opt for 3/4" instead of 1/2" as it would be much easier to grip when pulling.


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## scrogers (Feb 22, 2016)

Well... it happened and ultimately, was a huge success. We succeeded in building a 24ft revolve with an off-stage manual rope drive system that was actually incredibly reliable, smooth, quiet, and relatively easy to operate (with strength). The drive system was ultimately about 120ft of 5/8in multiline rope spliced into a loop, with knots tied about every 6ft. I then made a series of notched blocks (really a beveled 2x4 sandwiched with ply), or "cups" as some have described, bolted around the edge of the table, and then two sheaves coming off the table and a third large return sheave providing tension. There were initially a number of issues with keeping the rope from slipping off the sheaves, but with the proper alignment, tension, and various guides in place, the system became rather reliable.

With nothing on the table, it was rather easy to move with one person. I credit this to the high quality (and number) of casters we used in the construction. This also made the unit nearly silent to operate. Once you loaded it up, the hardest part was getting it to start... and then stop. Ultimately, we had two strong backs operating it the entire show. While a little difficult to calculate, we estimate it was moving between 7000-8000 lbs at it's peak (2 times in the show- about 30+ people, plus 8-10 rolling pieces of scenery, wagons, and staircases, plus the weight of the disk itself). With that much weight, it didn't move very fast, and it took a lot to go, but go it did, and it was honestly slick. The final locking/brake system was constructed out of a 1.5ton scissor car jack placed 2-3 feet under the disk that was operated via a long shaft to a drill (to raise and lower the jack). This made it extremely stable when not moving.

The whole thing was dismantled yesterday back into 4x8 (or smaller) sheets and is safely stored until the next time we need it...

Thanks to all who guided, suggested, and chimed in here, it's a great place. I'll put in a couple pics below and am happy to chat more with anyone... It was quite the process. Thanks again!


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## microstar (Feb 22, 2016)

Thanks for the wrap-up! Glad it worked out well. Great pictures.


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## BillConnerFASTC (Feb 23, 2016)

Nice work!


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## jwh78 (Feb 24, 2016)

Do you have a pic of the car jack break mechanism?

Sent from my Nexus 7 using Tapatalk


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## scrogers (Feb 24, 2016)

jwh78 said:


> Do you have a pic of the car jack break mechanism?
> 
> Sent from my Nexus 7 using Tapatalk



It's sorta hard to see it exactly, but basically there is a low-profile scissor jack slid underneath the disk, and then a long shaft to a drill. This would raise and lower the jack in a couple seconds. In these pics (below) the unit is pulled out rather close to the edge, however, when we were actually using it in the show, the jack was probably more like 1.5-2ft under the disk. I actually took a little bit of sticky-backed sand paper and put it under the base on on the top of the jack to increase the friction when expanded. Not sure it did much, but couldn't hurt.

It actually worked amazingly well, and the only issues we had were the makeshift drive shaft coming apart at the point where the hook attaches (a drill press and bolts fixed this), and then one bit of operator error where the jack hadn't been lowered all the way and a passing block caught on the driveshaft while the table was spinning and sucked the whole unit under... This actually bent/mangled things up a bit, but we were able to hammer it all back into shape, no harm... Things were running smoothly by the time we hit the shows.

Hope it helps.


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## jstroming (Feb 26, 2016)

Just out of curiosity, how do you trace and cut out a circle that big? Some kind of a wooden arm bolted to the center of the deck, then a pen on the end that rotates around center? Cut it with a jig saw?


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## scrogers (Feb 26, 2016)

jstroming said:


> Just out of curiosity, how do you trace and cut out a circle that big? Some kind of a wooden arm bolted to the center of the deck, then a pen on the end that rotates around center? Cut it with a jig saw?



You basically hit the nail on the head. I first laid out the two layers of ply on top of each other in a 24ft x 24ft square, then put a few screws in every sheet just to keep it together during the process. I then took a 14ft piece of strapping and drilled a hole just a little smaller than a sharpie, and screwed it in the exact center of the square. Then spun it. A couple of sharpies later... I had a rather perfect circle.

I then took a jig saw (or really, two) and starting cutting (one from one direction one from another). We had helpers slide 2x4's under the edges as we went around the circle so the blade didn't collide with the floor while cutting. It admittedly took a while since I wanted an accurate cut, which is why I added a second person and saw.

I actually snagged a some pics of the cutting, but we'd already made the circle when these were taken...


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## jstroming (Feb 27, 2016)

Very nice. I own a 4x8 CNC router so it could make a pretty accurate turntable in no time! But interesting how to make it without one.


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## scrogers (Feb 27, 2016)

jstroming said:


> Very nice. I own a 4x8 CNC router so it could make a pretty accurate turntable in no time! But interesting how to make it without one.



Oh nice! Yeah, we have a decent shop and tools etc, but afraid not quite a CNC router table... I imagine you could make the outside pieces of the disk very accurately with the right math. Overall, while certainly not perfect, the jig saw and 2x4 method worked out pretty well for us. Thanks!


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## jwh78 (Feb 29, 2016)

I'm so fascinated by this. VERY cool build!


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## Scott Growdon (Jun 21, 2016)

Question: What was your final cost for the revolve? Looks great!


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## scrogers (Jun 22, 2016)

Scott Growdon said:


> Question: What was your final cost for the revolve? Looks great!



Thanks for the interest Scott. I just went back to look at some of the numbers-

All in, I was right about $2750 for this project, *BUT*- I already had some parts from a much smaller prior turntable project years ago. The casters are the big thing, and I wanted good quality, quiet casters, which aren't cheap. I already had about 50 of them, but, as this saga unfolded, I needed many more (nearly another 70). I also had all the rope leftover from a rigging project a few years ago. It also should be noted that there is a considerable amount of time and labor, but I sorta see both of those as "free."

So, if I was starting this exact project with nothing, I'd estimate the costs closer to $4000(+).

There are ways to make it cheaper, but I think it would be at the cost of quality of the end product, and in the end, I was also marketing this as a longer term investment since it'd all be stored for future use. You could use cheaper 4in casters, and I actually even experimented with some knock-off "blue" casters in the beginning. I actually couldn't believe how noisy they were and poorly they rolled. There was just no comparison to the Blickle casters, other than they looked similar. Also, that much AC ply isn't cheap, but again, you want a really nice smooth rolling surface, so I needed AC for at least one layer.

The quotes I was getting to rent similar revolves weren't terrible by the week... but my people wanted the unit for 5+ weeks and with delivery etc, those costs became extremely high, not to mention I lose all the long-term investment into a short-term rental.

Looking back on it all, it was a great project and a good experience. Plenty of stress and hiccups along the way, but in the end, it was very successful.


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