Need to build a temp Proscenium

RonHebbard

Well-Known Member
Premium Member
I need to build a temp Proscenium, 2 columns and a top truss bolted together from wood. It is supported at the top by a flown bar. I have built flown flats before, but not a Proscenium.
What size timber is needed for the frame and basic layout. I am worried I will over engineer it.
Good whatever time is appropriate @deltamirage427
Several queries and a few of comments.

Queries:
- Indoor or outdoor?
- Will you glue all joints, or is that too permanent for you??
- Velour, lighter weight fabric, or plastic covered???
- Flame resistant, IFR rated fabrics????

Comments:
- The last time I did this it was built in situ for a 12 performance run over three weeks.
- The director wanted it left uncovered, self supported from the venue's deck, painted flat black, and to support four PAR20's and two EAW UB12's.
I used clear 16' x 1 x 2 inch pine at 90 degrees to one another, glued, liberally stapled with pneumatic brads then finished with two coats of flat black latex. The two verticals were 14' tall and screwed to the deck. The horizontal truss sat atop the verticals and was built in two 16' sections then bolted together at center with 5/16" hex bolts into three-pronged Tee-nuts.
It stood in situ for two weeks of rehearsals followed by three weeks of performance.
Then it was disassembled into four sections and moved to another venue for two weeks after which it was disassembled and put into storage. All four sections employed 1 x 2 inch diagonals again secured with pneumatic brads and good quality wood glue.

I too will admit to having a penchant for overengineering. On the plus side I slept well and my EAW's returned unscathed.
Toodleoo!
(From another of the colonies.)
Ron Hebbard
 
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Van

CBMod
CB Mods
Premium Member
I need to build a temp Proscenium, 2 columns and a top truss bolted together from wood. It is supported at the top by a flown bar. I have built flown flats before, but not a Proscenium.
What size timber is needed for the frame and basic layout. I am worried I will over engineer it.
Is the entire unit flown? The legs as well I mean. In that case, I would mount d-rings and keepers at the rail of both legs and along the bottom of the horizontal top flats. Attach wire guide at several points, at toggles works best. and at the top rail. Rig to batten appropriately.
to attach the d-rings and keepers and wire guides use a through-bolt; place the hardware, drill through to the face insert 10-24 or 1/4-20, torque until the nut is pulled into the 3mm ply. Snap the excess bolt off, grid it flush with a grinder, Bondo to finish.

All this is assuming you are building "Broadway" flats.
 
Is the entire unit flown? The legs as well I mean. In that case, I would mount d-rings and keepers at the rail of both legs and along the bottom of the horizontal top flats. Attach wire guide at several points, at toggles works best. and at the top rail. Rig to batten appropriately.
to attach the d-rings and keepers and wire guides use a through-bolt; place the hardware, drill through to the face insert 10-24 or 1/4-20, torque until the nut is pulled into the 3mm ply. Snap the excess bolt off, grid it flush with a grinder, Bondo to finish.

All this is assuming you are building "Broadway" flats.
The Columns (legs) are on the ground for the opening then the whole lot is flown. Yes, Broadway" flats.
What size lumber, as I am worried about over engineering and unnecessarily adding to much weight. I was thinking 70mm x 30mm Pine, but I was told I could use 42mm x 19mm Pine.
 
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Van

CBMod
CB Mods
Premium Member
The Columns (legs) are on the ground for the opening then the whole lot is flown. Yes, Broadway" flats.
What size lumber, as I am worried about over engineering and unnecessarily adding to much weight. I was thinking 70mm x 30mm Pine, but I was told I could use 42mm x 19mm Pine.
Man, you made me go look up all that metric stuff!
As I'm reading it 70x30mm is essentially 3"x 5/4" <2.5"x 1"> and 42x19mm is essentially 1x3 <3/4x2.5">.

It really depends what the overall size of the flat AND what the spacing on the vertical supports is. For flown stuff like this I prefer 1x4 19x88.9mm. idk what that is in standard metric lumber. I really need @RonHebbard to translate that to North of the border.
 

RonHebbard

Well-Known Member
Premium Member
Man, you made me go look up all that metric stuff!
As I'm reading it 70x30mm is essentially 3"x 5/4" <2.5"x 1"> and 42x19mm is essentially 1x3 <3/4x2.5">.

It really depends what the overall size of the flat AND what the spacing on the vertical supports is. For flown stuff like this I prefer 1x4 19x88.9mm. idk what that is in standard metric lumber. I really need @RonHebbard to translate that to North of the border.
@Van @RonHebbard Is old fangled and continues to think in Imperial dimensions and weights.
Ron (Stuck in the 60's) Hebbard
 
Is the entire unit flown? The legs as well I mean. In that case, I would mount d-rings and keepers at the rail of both legs and along the bottom of the horizontal top flats. Attach wire guide at several points, at toggles works best. and at the top rail. Rig to batten appropriately.
to attach the d-rings and keepers and wire guides use a through-bolt; place the hardware, drill through to the face insert 10-24 or 1/4-20, torque until the nut is pulled into the 3mm ply. Snap the excess bolt off, grid it flush with a grinder, Bondo to finish.

All this is assuming you are building "Broadway" flats.
The Columns (legs) are on the ground for the opening then the whole lot is flown.
@Van @RonHebbard Is old fangled and continues to think in Imperial dimensions and weights.
Ron (Stuck in the 60's) Hebbard
 
Sorry for the Metric. This is my design. I will use 89mm x 19mm pine for the rails. 19mm marine ply for the end plates to frame. I have 4 sections at 3m per section. Bolted together with 8 x 12mm grade 8 bolts and nylon lock nuts.
Does this build design look okay?
Is 3m to far between lifting points?
Also, I have seen an eye bolt layout on a set piece for lifting (attached image) . It does seem right to me.
 

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RonHebbard

Well-Known Member
Premium Member
Sorry for the Metric. This is my design. I will use 89mm x 19mm pine for the rails. 19mm marine ply for the end plates to frame. I have 4 sections at 3m per section. Bolted together with 8 x 12mm grade 8 bolts and nylon lock nuts.
Does this build design look okay?
Is 3m to far between lifting points?
Also, I have seen an eye bolt layout on a set piece for lifting (attached image) . It does seem right to me.
@deltamirage427 Eye bolts should be forged, preferably shouldered; NEVER bent wire which can / will unwind, open, and fail under load.

Edited: To correct skirted eye bolts to SHOULDERED eye bolts.
Toodleoo!
Ron Hebbard
 
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RonHebbard

Well-Known Member
Premium Member
It will be proper rated lifting eyes, lifting irons and all wire is also rated. I was more concerned that this other set had there eye bolt horizontal and working on the shear of the bolt. The bolt can handle it, but can the plywood?
@deltamirage427 GREAT query. I suspect it would be better / best if your supporting cables terminated in proper, welded and rated, hanging irons through bolted to your flats. As shown MAY be acceptable as a lateral guide.
@egilson1 &/or @What Rigger? Please comment.
Toodleoo!
Ron Hebbard
 

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