Need help with Triangular Prism

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Forum topic by Gricha posted 12-05-2014 04:48 PM 962 views 0 times favorited 4 replies Add to Favorites Watch
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4 posts in 3126 days

12-05-2014 04:48 PM

Topic tags/keywords: question theatre prism triangle design drawing

My wife runs a children’s school that has a theatre program. The Theatre director asked if I could make something for their background scenes for the upcoming year’s plays. She wants to have a vertical triangular prism that is on wheels (see the attached picture). The idea is that she and the students make scenes on paper (or paint directly on the wood) and they rotate the prism to change the backdrop as the scene’s change throughout the play. It will be about 5’ tall and each panel will be about 2-3’ wide.

Easy enough to make this out of a light panel material and attach wheels. What I could use some advice about is how to make this in a manner that it could be either broken down easily (without tools), or folded/collapsed for easy transportation in a mini-van. If they are permanently assembled, transportation and storage becomes difficult.

Also, what might be a good material to use for the panels? It has to be light enough to be carried, but not flimsy enough to fall over or collapse during use or moving.

Thanks for any advice,

4 replies so far

View Redoak49's profile


3292 posts in 2018 days

#1 posted 12-05-2014 05:12 PM

I think that I would consider making the top and bottom out of at lest 3/4” thick plywood(or doubled 3/4” plywood and then attach sides to it made of 1/4” plywood or mdf. Given the height, you may need a spacer half way up the prism. You could put it together with screws and then taken them out to take it apart. It will really depend on how many times you expect to take them apart and put back together.

You may want to look at the sizing to take the best advantage of plywood or sheet goods size. That is a 4 ft high prism would allow two cuts from a 8 foot sheet and 2 feet wide would be better than 3 feet wide. Making several of these will use up quite a bit of material pretty quick.

View ChrisK's profile


1974 posts in 3110 days

#2 posted 12-05-2014 05:30 PM

Kinda thinking out load here:

You might be able to use a French cleat type of system. Have the base cleat hold the panel up right and then use a cleat at the top of the panel to hold the top. The triangle shape should keep it it rigid when it is turned.

The lower cleat would need to be tall enough to keep the panel from tipping during assembly.

Maybe rare earth magnets in the cleats to help hold it rigid?

-- Chris K

View Gricha's profile


4 posts in 3126 days

#3 posted 12-05-2014 06:10 PM

I think if I were to make it ‘permanent’, than the way you describe, Redoak49, would be the perfect way to go. The problem I’m trying to solve is assembly/disassembly and transportation without tools. It would be moved from location to location several times a season.

I like the French cleat idea, including rare earth magnets. I’ll have to think about that more. Makes for easy assembly/disassembly.

I was also thinking about using two piano hinges (or sections of them) on two of the corners and a couple cam-locks of some kind to lock up the 3rd corner. This would let the 3 panels fold like an accordion for transport and storage. I don’t necessarily need a top or a full base (just enough for wheels and to stabilize the panels if the prism shape isn’t strong enough to do that).

View darinS's profile


709 posts in 2896 days

#4 posted 12-05-2014 06:54 PM

Trying to do a little thinking here. Guessing using 3/4” ply top and bottom with 1/4” ply for sides.

If you can live with a little overhang on the base and the top (maybe to be used as a guide for rolling the paper) then could you put it all together with through mortise and tenon. Gravity holds it all together, the through mortises keep the panels apart, and just lift off the top top take off the sides and you now have it broked down for transport and storage.

Hopefully I didn’t misunderstand your question.

-- They say many people die because of alcohol. They never realized how many of them are born because of it.

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