Tomcat 12" 'Cube' Constuction Method

[DSA]

Hi,

 

We are considering constructing a 8m x 8m x 4m (height) ground supported truss structure, for an upcoming event. The current truss under consideration is Tomcat 12" LDT, and I am considering how best to construct the structure whilst maintaining a safe process and the least amount of equipment. Trilite or similar is not suitable on this occasion.

 

What I mean by this is, "Can the structure be constructed without the aid of stands (e.g. Strata/Zeniths) or not?". Many processes have been going through my mind today, but I am wary that the truss is of a fair weight, and starting with an upright goalpost may not be the best option. Note that there are no flying points in the venue.

 

I wont go into the detail of my current thoughts, as they are probably not fully thought through yet, but I am interested to find out how you do it/don't do it. All of my ideas currently involve the lifting of a fair amount of bolted truss, which could be fairly heavy.

 

I have been to a few exhibitions recently where 12" structures have been used (notably at the NEC), just like I am describing, so I know that it is definately do-able, but I dont know quite how it was constructed!

 

Thanks,

David

[trussmonkey]

I would think about starting with one made up box lying on the ground (call it the Upstage box) add pieces to this box so that you start forming the roof box. Finish the roof box and you should have a 3d triangle structure . On the DS edge of the roof box start adding truss so that it raises the roof off the stage and starts to form the DS box. Once this is complete you can add in the 2 US/DS bottom trusses to complete the cube.

 

I hope this all makes complete sense!!!!

 

any questions just ask

 

TM

[flypig]

David.

 

I have built quite a few of these for exhibitions and events.

 

Several thoughts on this. 12" Tomcat (as you are probably aware) is classified as 'Light Duty'. So the first thing to consider is whether the truss is going to take the loads you intend to put on it (I'm sure you have been there, but just in case, here is some info for you.

 

Secondly, you will need some form of lifting devices (either fork lifts or Genie Super lifters - Genies are a cheaper hire option) to do this safely.

 

Therefore, if I were dong this then the method I would propose is as follows;

 

Equipment required: 12" Tomcat truss with 4 corner blocks. 4 Genie Superlifts. 4 off 3m Spansets. 4 of 2.5t shackles. 1 off EWP (scissor lift or cougar).

 

Proposed Method*;

 

1. Construct 8m box on ground complete with corner blocks.

2. Position 2 Genies on one side of box with 2 more Genies directly opposite (approx 1.5m in from corner blocks).

3. Lift box truss (1 side at a time) onto genies at lowest level and secure box truss to genies with spansets and shackles.

4. Raise Genies to slightly above height (4.1m) and place leg under corners 1 at a time assisting positioning and bolt up with EWP.

5. Once all 4 legs are in position and securely bolted up - lower Genies till legs rest on ground.

6. Using EWP, remove spansets and lower Genies.

 

REMEMBER! ALL the Genies MUST have ALL the outriggers correctly installed - if possible 'chock' the opposing wheels on the Genies with a couple of shot bags to prevent rolling.

 

You can either put the legs under as the completed 4m sections or place them 2m at a time.

 

The EWP will also come in handy for rigging lamps or whatever else the truss is intended for.

 

(* The above is purely a proposed method and we would advise that you seek the assistance of a good local rigging company to carry this work out for you)

 

Hope this helps.

[DSA]

Thanks Ian,

 

That is the method I had been thinking of. I did just wonder if there was any way of doing it without 'stands'/lifting devices (as they become redundant), however it would appear that the clear answer is no, mainly because of the weight of the truss.

 

Don't worry, the 600 odd kg UDL will be plenty for this application.

 

Thanks again,

David

[flypig]

Your very welcome David.

 

I have done it without any form of lifting device, you need to have a really good crew who know what they are doing and it's a real struggle getting the last legs in place.

 

Chookas with it, and post a pic of the finished item.

 

Best regards,

 

Ian

[SeanT]

Shame you can't do it with trilite, that's about possible in that size with four blokes and no lifting kit....

[flypig]

You are not wrong Sean, it's entirely possible - I've done it. But just because we've done it that way in the past doesn't mean it's a safe work practice.