Configurations of the Boomilever

[bobthebuilderman]

Hey SciOly Forums,

I know we're allowed to do this, ,

but I was wondering whether we were allowed to do this:

as an upside down triangle instead of a regular one.

Thanks,
Bob

[TheMadScientist]

The first configuration you posted is a picture of a tension boomilever. The second one is of a compression boomilever. Both are allowed but tension boomilevers are overall considered better because compression strength decreases with length- thus by making the compression member span the hypotenuse of the triangle you create, you increase the length and decrease strength. On the other hand, in a tension boomilever, the compression member is shorter and therefore stronger.

I would recommend reading the boomilever wiki page and going through past forums for a better idea of how to engineer your boomilever. Also, as a side note, remember that this year the boomilever attaches via a J-hook, not the three washers shown in your pictures.

Good luck and happy holidays!

[S4BB]

[MadCow2357]

Interesting design! If that's your boomilever, may I ask how much it weighed and how much it holds?

[Cow481]

Interesting design! If that's your boomilever, may I ask how much it weighed and how much it holds?

Also it is just me or is that longer than 45 cm

[waffletree]

Interesting design! If that's your boomilever, may I ask how much it weighed and how much it holds?

Also it is just me or is that longer than 45 cm

Like MadCow said, it's a really interesting design.
It does appear to be longer than 45cm...though that might just be because of the angle that the picture got taken
And are you worried about it wobbling side to side when it is on the wall?

[dholdgreve]

I believe it LOOKS longer than 45 CM because it is substantially narrower than what you are used to seeing. This appears to be in the 2.5 to 3 cm width, which puts everything back into scale. Interesting design, and if it works, great! However, I'd be concerned that the loading block is not centered on the tension to compression joint, it sits out beyond that point. This may make that connection a pivot point, or fulcrum. When load is added out there, it may push up on the inner side, adding an additional shear force to deal with.

[S4BB]

The loading block was at 45cm from the wall. The basic structure was 2cm square, and the tension members only attach in the lower right corners of the image (a few pieces of wood are missing from this image, broke during testing). The glue joint is not on the center line of the loading block, slightly forward. I could not find the exact numbers, but this boom scored just over 1800. Main tension members are Bass wood.

[S4BB]

https://photos.app.goo.gl/7xroPT44SVHT1SV1A

[Carrot]

The loading block was at 45cm from the wall. The basic structure was 2cm square, and the tension members only attach in the lower right corners of the image (a few pieces of wood are missing from this image, broke during testing). The glue joint is not on the center line of the loading block, slightly forward. I could not find the exact numbers, but this boom scored just over 1800. Main tension members are Bass wood.

How are you making the base of your boomilever? Are you just gluing your tensions to what looks to be a 1/4" by 1/4" piece?
Also, when connecting your tensions to the compression piece, are the tensions on the inside of your compression piece or on the outside?