Question about Boom Specs

[DN5135]

I was reading the specifications and I am not clear on the ruling over blocks attached to the boom.

What I would like to do is slot the boom and carry the blocks through their bails on a rod inside the boom. The sheaves would still be outside of the boom and this would in effect be the same as mounting a slotted carrier on the boom with a rod to carry the blocks. I like the approach because it is cleaner, less expensive, and the block positions could be adjusted through multiple slots.

I suspect this is not allowed, but that makes no sense to me if adjustable block positions are allowed. I was thinking of doing this with a standard 1.75"x2.75" aluminum boom extrusion.

[Geoff Sobering]

What I would like to do is slot the boom and carry the blocks through their bails on a rod inside the boom.

I'm not 100% clear what you're planning to do.  Is it similar to the setup in the attached photo?

Cheers,

Geoff S.
Us-5156

[Bob Gray]

 
The sheave of the block must be outside/clear of the boom. The rest of the pulley assembly may extend into the boom.
                         Bob

[DN5135]

The picture is exactly What I wanted to do!  Thanks for the help.

[Geoff Sobering]

The picture is exactly What I wanted to do!  Thanks for the help.

Anytime!  Glad to be able to help out.

As far as I know, it's a pretty standard technique for mounting blocks to a boom.  I'd recommend narrower and more closely spaced slots than are shown in the photo to get a finer adjustment capability. I have a Bryant extrusion (I think) with about 1/4" slots milled on about 1/2" centers that seems better than the setup I had when that photo was taken.

Cheers,

Geoff S.