turntables

[peachie]

I need to build a doughnut turntable and can not find any info on how to build one. I have multiple turntables all are friction drive so I would like to do the same with the one that I have to build. Height is not a problem because I am inserting it in a 3' tall deck. Its od is 32' and its id is 18'. I would love to rent one but it would need to stay in the deck for 3 months and I do not think a rental would be cost effective. I am having trouble wrapping my head around what to build the inside hub out of. Any ideas or places that have info would be great.

[Van]

Hmmmmm. Interesting conundrum! What's your budget like ? I could toss you a few ideas this evening. Got a busy day at work today, my two chief "helpers" are with me.

[Marko66]

The doughnut turntables that I have built, all had the center as a turntable. The doughnut tt had casters that held it away from the center tt. That being said, I would approach the center as a round platform legged to 36". The doughnut tt would be fabricated as an 8" tall unit. with a doughnut shaped platform 28" tall on top of it. A number of casters mounted on their sides would be mounted on the deck to bear against the inner 'race' of the 8" tall doughnut tt. (at the 18' mark)

What material do you plan to use for this tt? 30' diameter is a fair amount of real estate to be dragging around with a rim drive.

What hp have you determined to use for this project?

What part of the Country do you live in?

Sorry I have more questions than answers at this point, but, I guess, I am like that...

[FatherMurphy]

We built one when I was in grad school, 3/4" ply top with a 1/2" ply bottom on the donut's section frames. Fixed casters were mounted wheels up with axle aligned to center and shimmed to height, and horizontal casters spaced around the perimeter, with a golf cart tire drive on the edge. There was no center pivot for the donut, just the horizontal rollers holding it in place. The center was filled with a regular platform, both it and the outer surround cut to clear the minor irregularities of the donut. Overall height wasn't much more than a foot, but could easily be higher. All three, inner and outer platforms, and donut, were the same height above the deck, so we had to keep the gap minimized for actor safety.

The fun part was figuring out how to get the sections to fasten together, since the frame was enclosed top and bottom, and any misalignment would cause clearance and drive problems.

[ship]

Been probably 15 years since I last worked on a turntable but I do remember some details on how we constructed the larger ones. First concept was reverse the casters. Not on the platform, put them on the frame. Double side the platform and put some form of hardboard or deck plating under the platform across seams to the platforms if possible so as to reduce friction and warp at the seams.

The casters were attached to their own framework that was spiked into the deck on install. One might even better yet do ball casters but one would need more of them to get it done properly due to the weight or pneumatic lift mechanism in getting really advaned. Spend more on the caster or lift mechanism but than save money on the drive mechanism.

Anyway as general concept the casters were installed onto a frame on the deck and the platform rode on it. Don't remember the center pivot other than a greased and sleeved pipe - sorry, and assming that is what we used. Tech Notes for past issues of TCI should have ideas and drawings as with past tech note from the high school/college anual conference name to such a book of tips. This also in I'm sure there is other books out there that tell how to do it if not only the tech bible "Scencery for the Theater."