Hanging Scenery

[Nick LX]

I've always wondered about hanging wooden scenery/flats etc. Is plywood the best wood to use?

 

Also, if hanging from two points using shackle plates, how much weight can the plywood itself support.

 

Quite simply, what are some rules of thumb on wood thickness and how strong it is etc...?

 

(Sorry if this has been covered before).

[indyld]

For the wood itself, it comes down to the area which the load is spread over (I.e how big the plate on the other side of the bolts are and the direction of tension and/or compression.)

 

http://www.fpl.fs.fed.us/documnts/fplr/fplr1315.pdfMy link

 

This has some info:

 

http://www.tecotested.com/techtips/pdf/tt_plywooddesigncapacities

 

I know this isn't the 'rule of thumb' hoped for, but it comes down to the stress and modulus of elasticity which I'm sure our engineering-y friends know more about than I. Truth is, I've never known anyone hanging scenery to do anything other than "that'll do" 'calculations'. While flying irons have particular ratings, what you attach them to usually doesn't and relies on construction conventions and experience rather than calcs. Am sure that some the scenery hangs I've seen/taken part in theatre wouldn't really fare that well with genuine calcs, even the methods and uses of standard Flints hardware.

 

I'd be interested to know if anyone does have a such a rule, as I've certainly never heard of any.

 

Edit to add: Rather worryingly, the linked to plate suggest Tension: Do Not Use so am at a bit of a loss as to what good it is. Hanging anything with it puts tensile stress on at least some parts of the assembly....

[paulears]

It's much safer and simpler to hang from the bottom, and then use hanging irons or other similar items to take the weight at the bottom, as if they're on the floor - and then secure the wire rope with a grummet at the top - far less stress and strain on the construction, as gravity works for you, and not against.

 

Flints link

http://www.flints.co.uk/acatalog/Hanging_Iron_Small.gif

[indyld]

... far less stress and strain on the construction, as gravity works for you, and not against.

 

Just to be finicky, the forces involved remain the same, they just change in nature. Instead of a flat trying to 'stretch' below the fixing point, it compresses 'up' toward the sky (or down towards the floor, if you prefer). In terms of fixings, the forces don't change but assuming that the jointing in construction is stronger in compression than in tension (commonly would be) then the joints can cope more easily. Normal grained wood is stronger in tension along the grain rather than across it and obviously plywood is more even in this regard. Board like MDF or chipboard, not so strong under tension in any direction.

[dbuckley]

What we use is a length of wire (8m long from memory) with nicopressed loops on each end (purchased as a complete rated assembly) and drill holes through every cross-member of the wooden frame, and the wire goes in a 'U' through and under the frame.

[Roderick]

You will also find that hanging flats from the bottom makes them hand straighter than hanging from the top.....

[Nick LX]

Wonderful. Thanks for all of the information guys.