Built my boom pole today

[Sublifer]

Nice looking build I am sure that will be very handy.

Could someone explain or point me to the other threads that explain in detail why that lower brace should line up under the upper truss brace ?

Its physics... If the main pole is stressed to the point of bending then the upper brace takes some of that pressure. As it the weight pulls it down, that force is going to be sent down that middle support. Since the bottom brace is not there then that force would be a direct downward force to the main beam again and the next weak point would be at the end of the bottom brace and is where it would bend. Clear as mud? If you really wanted to visualize it you could mock it up with something flexible and see where it bends as you adjust supports

 

[beenthere]

Nice looking build I am sure that will be very handy.

Could someone explain or point me to the other threads that explain in detail why that lower brace should line up under the upper truss brace ?

Has to do with bending moments. Where it is located now has a weakening effect on the structure.

 

[bcp]

Lifting too much:

 

[tburk49760]

Thanks for the positive words and the input as well, I feel kinda dumb for not thinking of the brace positioning. The main beam is an old trailer axle and is very thick and heavy so the upper truss is mostly for looks? I intend to use it only when the hoe is on for ballast and mostly keeping the tip at or below the level of the bucket to minimize the chance of tipping. Already used it to move my hydraulic blade into the shop and am very pleased with it's usefulness.

 

[tburk49760]

And yes that is a Howard Rotovator with the English motor lurking in the background. Runs well, weighs a lot.

 

[evo803]

Its physics... If the main pole is stressed to the point of bending then the upper brace takes some of that pressure. As it the weight pulls it down, that force is going to be sent down that middle support. Since the bottom brace is not there then that force would be a direct downward force to the main beam again and the next weak point would be at the end of the bottom brace and is where it would bend. Clear as mud? If you really wanted to visualize it you could mock it up with something flexible and see where it bends as you adjust supports

If the beam is going to buckle at that point where the truss support post is why would adding more stress to that area from the brace below help it from failing ? The beam is trying to bend which pushes upwards and the truss is supposed to resist that force , so if that upward force is increased by having the main support post at that area wouldnt that just add more stress to the truss and cause it to fail anyway ?

Thanks everyone for trying to help I am just trying to wrap my mind around this .

 

[Iplayfarmer]

If the beam is going to buckle at that point where the truss support post is why would adding more stress to that area from the brace below help it from failing ? The beam is trying to bend which pushes upwards and the truss is supposed to resist that force , so if that upward force is increased by having the main support post at that area wouldnt that just add more stress to the truss and cause it to fail anyway ?

Thanks everyone for trying to help I am just trying to wrap my mind around this .

The beam is going to buckle where the brace from underneath meets the beam. This is where the opposing forces are all greatest. Putting the truss support directly above this point sandwiches that point so that the truss support above pushes down to help counter the force of the brace pushing up.

 

[trook]

I guess I'm a little slow. Can someone insert a diagram of the proper way to add the supports?

 

[Iplayfarmer]

I guess I'm a little slow. Can someone insert a diagram of the proper way to add the supports?

Here's my proposal...

 

[evo803]

The beam is going to buckle where the brace from underneath meets the beam. This is where the opposing forces are all greatest. Putting the truss support directly above this point sandwiches that point so that the truss support above pushes down to help counter the force of the brace pushing up.

By doing this aren't you adding more total forces to this area therefore making it the weak point ?