Boomilever B/C

[fanjiatian]

http://scioly.org/w/images/f/f5/AiaDist ... eView1.png

I still don't get it, if the tension member was glued on top of the compression member like a lap joint, how would you connect the bracings between the two? The tension and the compression member wouldn't be in the same plane...
Could someone help me visualize this?

[Aia]

http://scioly.org/w/images/f/f5/AiaDist ... eView1.png

I still don't get it, if the tension member was glued on top of the compression member like a lap joint, how would you connect the bracings between the two? The tension and the compression member wouldn't be in the same plane...
Could someone help me visualize this?

My tension members "curved in" towards the base, so I was actually able to use lab joints for the connectors between tension and compression.

[fanjiatian]

What do you mean by curve in? Is that where you angle in both sides so that the strcutre gets narrower towards the loading point?
Or did you actually bend the tension members so that it's on the same plane as the compression member?

[iwonder]

I have trouble visualizing too, no sweat. Basically, the tension members start 5cm apart to accommodate the loading block, but end less then 2cm apart in order to not waste weight in the base. Maybe angled in would be a better term.

[thsom]

Would bending the would put any minor additional stress? Also, what happens if you sand off the excess gorilla glue and what if you don't have clamps but the joint is tight?

[iwonder]

I haven't got the gorilla glue on my boom yet, I've always assumed I could just let the joints set if they were similar to base-tension joints... Aia?

And it does put some minor stress on it(someone else may be able to verify) but I think the lighter base is more than worth it for the smaller gain in tension weight.

Alas, my efforts to avoid gorilla glue were in vain, I got up to 4.17kg and a tension member(completely cleanly, I might add) pulled out of the base. I shall try again soon(maybe with the real rules) using gorilla glue this time. Seeing as I've never used it, does the wood have to be clamped, or can the glue simply be applied and left alone for 24 hours?

[fanjiatian]

I have trouble visualizing too, no sweat. Basically, the tension members start 5cm apart to accommodate the loading block, but end less then 2cm apart in order to not waste weight in the base. Maybe angled in would be a better term.

I see. Are the compression members parallel or do they also angle in too?
If not, I don't see how you could angle the tension members in without actually physically bending it.

[iwonder]

The compression members are not angled in(the point where the compression member meets the wall would be unstable), personally, I just bend the tension members slightly(I think there was some talk about added stresses above), however you could technically miter everything.

[fanjiatian]

What methods do you use to bend the tension member in the same way each time?

Also, did you use a jig while constructing your boomilever in a way similar to building a tower?

[retired1]

Not addressed to me, but for a sharp bend, I would do what Aia said, use tiny shims and glue.
If you really want to bend it, put the tip in boiling water for a couple of minutes, dry it with a towel and put it in a jig that is the exact shape that you want it to be. I would put both pieces in the same jig at the same time (side by side) and slowly tighten the screws/bolts.

Nuke it twice for 30 seconds each and let it set overnight.

An assembly jig will speed up making a truss as well as it will come a lot closer to having two sides the same vs pins in a sketch. It does take a bit of time to make a jig, but you will probably be making at least 3 boomilevers.