# Rubber or Polyurethane? Revolve caster questions



## Dreadpoet (Aug 29, 2012)

I'm building a 18' revolve and expect a 18' X 14' flat constructed set on it with a little furniture and 4/5 people on it at any given time. My question is in caster land...do I want rubber or polyurethane casters, 4" or 3" (why) and how should I estimate load. Final question...I see than van and others place the casters in concentric circles leaving casters further apart as they move away from the hub....is there a reason for so many so close to the hub? I know that there has been a reasonable amount of discussion on the revolve/turntable but I did not see a definitive weigh in on these.


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## JLNorthGA (Aug 30, 2012)

I usually use hard rubber or "elastomer" casters as they typically have a higher weight capacity. I like larger casters as they can go over things a bit easier.

However, if budget is no option, go for something like "Stagemaster" casters. They have twin wheels and typically three sets of twins per "plate" - did I mention budget - they cost a LOT.

I typically get hard rubber 5" swivel casters. The accessible ones are locking. The inaccessible ones are not. I just build the revolve or set to conceal the caster. I usually have more casters in the critical points with the most weight - usually this is the hub.


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## beachbum (Aug 30, 2012)

In my experience, polyurethane is problematic. I "inherited" a large stock of 5" Colson polyurethane casters many years ago when I took my current job, and used them for a stock 34' turntable. While the load bearing properties are very good, I learned that over time,3-4 years, the poly keeps on catalyzing until it gets like clay and begins to crumble. My dealer verified this. Since enough casters to do a reasonably sized table represents a large investment, I'd go with something else. I use a local industrial caster company, and they are most helpful in solving problems. I eventually went to a Colson Mold-On rubber 5" wheel, and have had no problems since. They are not the cheapest casters out there, but the quality and durability are worth it.


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## danTt (Aug 30, 2012)

JLNorthGA said:


> I usually use hard rubber or "elastomer" casters as they typically have a higher weight capacity. I like larger casters as they can go over things a bit easier.
> 
> However, if budget is no option, go for something like "Stagemaster" casters. They have twin wheels and typically three sets of twins per "plate" - did I mention budget - they cost a LOT.
> 
> I typically get hard rubber 5" swivel casters. The accessible ones are locking. The inaccessible ones are not. I just build the revolve or set to conceal the caster. I usually have more casters in the critical points with the most weight - usually this is the hub.



Triple Swivel casters on a revolve are probably not the greatest idea. Not worth the expense and adds much more resistance if you need to spin it in the opposite direction.


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## Van (Aug 30, 2012)

danTt said:


> Triple Swivel casters on a revolve are probably not the greatest idea. Not worth the expense and adds much more resistance if you need to spin it in the opposite direction.



Not just "triple swivel" No Swivel casters are good for Revolves. A turntables ability to reverse direction easily, quietly, and quickly depends on you constructuing it with straight casters. 

The harder the cast the better.


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## JLNorthGA (Aug 31, 2012)

Van said:


> Not just "triple swivel" No Swivel casters are good for Revolves. A turntables ability to reverse direction easily, quietly, and quickly depends on you constructuing it with straight casters.
> 
> The harder the cast the better.



So you are saying use straight casters and have them aligned so they are perpendicular to the radius? Makes some sense. I usually do "wagons" and have to move them around the side and back stage areas. For those applications, a straight casters doesn't work too well.


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## Dreadpoet (Aug 31, 2012)

van, I would love to hear you weigh in on determining load per caster/weight distribution and why casters are closer together as we get nearer to the hub. I understand the comment earlier that it might have to do with where the majority of your weight is....but I would think that would change from scene to scene and as the thing actually revolves.


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## kicknargel (Sep 5, 2012)

If you really want to get into the theory and math of caster loading in a revolve, read "Structural Design for the Stage" by Holden and Sammler.

Amazon.com: Structural Design for the Stage (9780240803548): Alys Holden, Ben Sammler: Books

Always rigid casters on a revolve. 

Digression: there's a story amongst old-guard stagehands in Boulder, CO about building a giant slip stage for a music festival at the stadium at CU. The installed the caster plates square to the stage, but the wheels weren't quite square to the plates, so every time the thing traveled, it wandered a couple more feet off its path.


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## josh88 (Sep 5, 2012)

JLNorthGA said:


> So you are saying use straight casters and have them aligned so they are perpendicular to the radius? Makes some sense. I usually do "wagons" and have to move them around the side and back stage areas. For those applications, a straight casters doesn't work too well.



Generally speaking, yeah, mounting them on the floor is even better if you can so the revolve sits on top of them. Dumb casters help keep it all in place, with swivels, every time it spins to change direction it walks a little bit till you need to move a piece back into place.

And as was pointed out above me, the walking can still happen if you don't get it all straight.
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