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Scaff V Doughty Arms


Scaff V Doughty Arms  

20 members have voted

  1. 1. Would a 1m Alloy Scaff bar attached to a scaff clamp be stronger than a 1m doughty welded boom arm?

    • Yes
    • No
    • This poll is dangerous and you should try to find a professional engineer to answer the question!

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Is the welded Doughty the ali scaff welded to an omega clamp type boom arm?


I imagine he means these: http://www.doughty-engineering.co.uk/cgi-b...showprod_T57310


Tube welded to a half coupler.



Get your calculator out and work out the force exerted at 1m. Or use someone's code: http://www.engineersedge.com/simple_levers_menu.shtml


90degree coupler can hold - 750kg - http://www.doughty-engineering.co.uk/cgi-b...showprod_T57102


Boom arm ratings - http://www.doughty-engineering.co.uk/shop/...iles/t57310.pdf

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Umm, correct me if I'm wrong someone, but the weld itself is probably stronger that the aluminium it's holding together?


Perhaps. However, depending upon the aluminium alloy used, the metal in the heat affected zone next to the weld will be softened. The reduction in strength can vary from 20% to 80%. (Hind, P., 2001. p.18, Aluminium Structures in the Entertainment Industry, Entertainment Technology Press).

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The other way of thinking about it is Doughty give you a spec for their system.

What is the Spec on a Clamp.!!!


NO spec therefore Doughty WIN


No Spec?


Safe working loads for individual couplers


Right angle coupler (Class A)

Slipping force in kN 6.1 (1)

Cruciform stiffness in kNm/rad 10.0 (2)

Cruciform bending in kNm 0.24 (2)


Right angle coupler (Class B)

Slipping force in kN 9.1 (1)

Cruciform stiffness in kNm/rad 15.0 (1)

Cruciform bending in kNm 0.28 (1)



(1) These figures are based on table 8 of BS EN74-1 : 2005 and are for use with type 4 steel tubes

(2) Data on crusiform strength and stiffness shall be obtained from the supplier / manufacturer


Referance TG20:08

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