# 12" Truss Cantilever- Acceptable Overhang?



## jstroming (May 29, 2016)

Is there an acceptable length of standard 12" truss (let's say Light Duty Tomcat Box with Plates) that can be extended past a point, assuming there is nothing hung on the truss past the point? I realize there's potentially a few other variables here, but figured there must be someone with some guidance, who would start asking questions beyond, say 8ft. Last time I looked at a truss spec sheet I remember seeing distributed load totals but nothing about cantilevered truss.


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## Footer (May 29, 2016)

Cantilevers are kind of weird. Depending on how they are loaded they can actually make the entire system carry more weight and deflect less. It all comes down to how they are loaded and what that is doing to the point itself and the system as a whole. I wouldn't want to see a cantilever past the center point of a stick, but that is more of a gut thing that I have no backup for.

I attached Delbert Hall's truss rigging calculator. There you can easily see how changing the cantilever affects the whole system. Don't take that calculator as gospel though, you need to do some reading before what all it can do makes sense. There is a lot of math that goes into this and there is no hard and fast rule. All truss makers will tell you that they design their truss so it does not matter how many sticks of truss you have. When correctly attached together they form one system that can be looked at as one beam, not many bolted together.


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## egilson1 (May 30, 2016)

There are a few things to consider with cantilevers. First, can the truss itself support the load at a given length. Second, are the loads balanced so that the truss stays stationary and doesn't become a teeter totter. Third, do the suspensions have enough strength to support the increased load created by he cantilever. 

The calculator Footer shared will help with the second two items. For the first there is a rule of thumb you can use for determining if the truss itself can withstand the forces. The maximum cantilever load is equal to the center point load of a span 4 times the length of he cantilever. So for a 10' cantilever you would look up the CPL of a 40' span. 

Again, this is only one part of determining if a cantilever is possible for a given situation. You still need to make sure the suspensions can handle the loads, and that the system is balanced to prevent movement. 



Sent from my iPhone using Tapatalk


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## Dagger (May 30, 2016)

What's a 40' ? 
Someone explained it in another post I still don't quite get it 

I need to see a pic to understand can someone pos one please


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## jstroming (May 30, 2016)

Wow this is all great info. A lot for me to look into. Thanks!


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## cbrandt (May 31, 2016)

I would strongly advice you to call the manufacturer for the type of truss you're using. You'll get vastly different answers based on company, but largely I've found that if you can ask them specific questions about what you're doing, they're incredibly helpful about ways to solve problems.


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## josh88 (May 31, 2016)

Dagger said:


> What's a 40' ?
> Someone explained it in another post I still don't quite get it




egilson1 said:


> CPL of a 40' span



You don't need a picture. What he just said was the center point load of a 40' span. 

*SPAN*
_noun_

*1*. 
the full extent of something from end to end; the amount of space that something covers.
"a warehouse with a clear span of 28 feet"

synonyms:extent, length, width, reach, stretch, spread, distance, range
"a six-foot wing span"
[TBODY]
[/TBODY]


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