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musicalwhang wrote:Would a 1/4" diameter wooden dowel at 3cm suffice butt-jointed between 2 bass tension members at 1/8x1/16?

Would it suffice? Likely not, but depends on your goals and what your design is. Try increasing the surface area on the tension member...

A better way would be to very carefully cut grooves in the end of the dowel that will just fit the tension members . I used Devthane 5, but a good epoxy will work well.
The real trick of this is to get the two end cuts to be perfectly parallel. If it is not, re cut a new piece. The joint will withstand a great amount of abuse and still not fail.

Thank you for the responses. Another question: I was wondering what the trusses that connect the tension members and compression members do for the boom. Some designs have it but some don't.

musicalwhang wrote:Thank you for the responses. Another question: I was wondering what the trusses that connect the tension members and compression members do for the boom. Some designs have it but some don't.

They have two purposes:
1. Preventing the boom from "splitting open".
2. Prevent buckling along the compression member

MadCow2357 wrote:

musicalwhang wrote:Thank you for the responses. Another question: I was wondering what the trusses that connect the tension members and compression members do for the boom. Some designs have it but some don't.

They have two purposes:
1. Preventing the boom from "splitting open".
2. Prevent buckling along the compression member

yea ^^that
and prevent the whole boomi from collapsing because it's too much pressure downwards for the chords to handle
also to make the boomi firm and prevent it from wobbling side to side
just adds support overall like you dont see real life cranes with no trusses at all

I'm having trouble visualizing how the dowel attaches to the tension members. People on this forum have recommended putting in a small grove on the dowel in order to make the tension member attach to the dowel on all 4 sides. Can someone explain how this can be done and why this is best option? are there also different options on how the j-hook should latch onto the boomi?

You should have 2 tension members attaching to the dowel, not 4. The reason that the notched en is best is that you have more glue surface, thus a stronger joint.
The dowel option is probably the best because of the less wood (weight) and the ease of attaching it to the hook.

Put tension member into the grove, then laminate it with a sheet. This way, 4 sides of the tension member are glued to the base.

Wouldn’t it be easier and more effective to just drill a hole and gorilla glue the tension pieces to the dowel rod?

Cow481 wrote:Wouldn’t it be easier and more effective to just drill a hole and gorilla glue the tension pieces to the dowel rod?

If the tension is a square piece of wood and not round then using a drilled hole will reduce the surface area of the joint. A notch will a allow for more coverage since the flat edges will have more contact with the wood.