Boomilever B/C

Anonymous15
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Re: Boomilever B/C

Postby Anonymous15 » January 16th, 2019, 2:44 pm

For the 2nd question I was wondering how to figure out how long to make the tension members (we are doing .a tension design) compared to the compression members so that when the base goes around the J-hook, the ends of the compression members will touch the testing wall perfectly flat. I'm just worried that my compression members will be too long for the tension members, so the compression member ends won't make good contact with the testing wall. Is there anything I can do to make sure this isn't a problem?

And thank you for your answer, it was very helpful!

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Re: Boomilever B/C

Postby Cow481 » January 16th, 2019, 4:14 pm

For the 2nd question I was wondering how to figure out how long to make the tension members (we are doing .a tension design) compared to the compression members so that when the base goes around the J-hook, the ends of the compression members will touch the testing wall perfectly flat. I'm just worried that my compression members will be too long for the tension members, so the compression member ends won't make good contact with the testing wall. Is there anything I can do to make sure this isn't a problem?

And thank you for your answer, it was very helpful!
This may not help if you don’t have a testing setup but what I do is stack rulers on the setup and tape down my compression pieces to them and glue the base to the tension pieces and put the base and tension pieces on the j hook and just glue the two pieces together.
Make sure the tension pieces are longer than needed so you can just cut the rest off
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Re: Boomilever B/C

Postby Carrot » January 16th, 2019, 5:01 pm

For the 2nd question I was wondering how to figure out how long to make the tension members (we are doing .a tension design) compared to the compression members so that when the base goes around the J-hook, the ends of the compression members will touch the testing wall perfectly flat. I'm just worried that my compression members will be too long for the tension members, so the compression member ends won't make good contact with the testing wall. Is there anything I can do to make sure this isn't a problem?

And thank you for your answer, it was very helpful!
This may not help if you don’t have a testing setup but what I do is stack rulers on the setup and tape down my compression pieces to them and glue the base to the tension pieces and put the base and tension pieces on the j hook and just glue the two pieces together.
Make sure the tension pieces are longer than needed so you can just cut the rest off
I do something similar to this when I attach my compression to my tension, however, I often find that my base is not centered above the compression. Do you have any tips for aligning the compression with the J-hook or gluing the tensions to the compression and making sure that both of the tensions are glued to the same point / pulled the same amount?

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Re: Boomilever B/C

Postby MadCow2357 » January 16th, 2019, 5:52 pm

Do you have any tips for aligning the compression with the J-hook or gluing the tensions to the compression and making sure that both of the tensions are glued to the same point / pulled the same amount?
Draw lines on your testing base to help align the boomilever. Obviously, they won't have those lines at competition but once you test enough you start getting the feel of how to align your boomilever even without lines or a level. For making sure the tension members are glued to the same point, precut the tension members to the length you want by putting it on your to-scale drawing. Then, attach the tension member to the distal end. There's actually no need to use a protractor and measure every angle if you just position everything on a to-scale drawing. Beyond that, it's just being careful.
For the 2nd question I was wondering how to figure out how long to make the tension members (we are doing .a tension design) compared to the compression members so that when the base goes around the J-hook, the ends of the compression members will touch the testing wall perfectly flat. I'm just worried that my compression members will be too long for the tension members, so the compression member ends won't make good contact with the testing wall. Is there anything I can do to make sure this isn't a problem?

And thank you for your answer, it was very helpful!
This may not help if you don’t have a testing setup but what I do is stack rulers on the setup and tape down my compression pieces to them and glue the base to the tension pieces and put the base and tension pieces on the j hook and just glue the two pieces together.
Make sure the tension pieces are longer than needed so you can just cut the rest off
Draw a full scale drawing accounting for the j hook at a distance of 4.5 cm. You don't need to find the distance of the tension member, you just connect the dots after you draw the compression members and the line representing the height of your boom. Like Cow481 said, make the tension members longer so you can cut them off. That's very important.
Last edited by MadCow2357 on January 18th, 2019, 3:57 pm, edited 1 time in total.
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Re: Boomilever B/C

Postby Anonymous15 » January 18th, 2019, 2:45 pm

Thanks for all the info!

I actually realized that I had a few more questions about construction:

1. What is a lamination?

2. How do you build your base? I don't know how to calculate the force the base undergoes, so I don't know how to build it efficiently. I'm thinking of putting a stick of 1/4 x 1/4 inch bass as the base and glue it to my 3/32 square bass tension members. Is this viable?

Thanks again!

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Re: Boomilever B/C

Postby bernard » January 18th, 2019, 2:59 pm

Thanks for all the info!

I actually realized that I had a few more questions about construction:

1. What is a lamination?

2. How do you build your base? I don't know how to calculate the force the base undergoes, so I don't know how to build it efficiently. I'm thinking of putting a stick of 1/4 x 1/4 inch bass as the base and glue it to my 3/32 square bass tension members. Is this viable?

Thanks again!
Lamination is adhering together sheets of material, in this event wood. An advantage is you can alternate grain orientation making the material more consistently strong in all directions. Plywood is made by gluing plies of wood with adjacent layers glued with grain at alternating angles.
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Re: Boomilever B/C

Postby MadCow2357 » January 18th, 2019, 3:19 pm

Thanks for all the info!

I actually realized that I had a few more questions about construction:

1. What is a lamination?

2. How do you build your base? I don't know how to calculate the force the base undergoes, so I don't know how to build it efficiently. I'm thinking of putting a stick of 1/4 x 1/4 inch bass as the base and glue it to my 3/32 square bass tension members. Is this viable?

Thanks again!
The method you described is how I've been building my bases. However, make sure to increase the surface area of the bass tension members.
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Re: Boomilever B/C

Postby Anonymous15 » January 18th, 2019, 6:42 pm

Ok, I understand. I'll make sure to get the alignment right too.

I was just rereading Aia's boomilever guide, and I noticed that the distal end has no bracing in the compression members (which made sense, as that's where the bucket hangs under). But won't that make the distal end really weak? Isn't bracing supposed to span the whole compression member?

And sorry for all the questions, but the answers are really helping me out!

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Re: Boomilever B/C

Postby MadCow2357 » January 18th, 2019, 6:50 pm

Ok, I understand. I'll make sure to get the alignment right too.

I was just rereading Aia's boomilever guide, and I noticed that the distal end has no bracing in the compression members (which made sense, as that's where the bucket hangs under). But won't that make the distal end really weak? Isn't bracing supposed to span the whole compression member?

And sorry for all the questions, but the answers are really helping me out!
That is true, without bracing the distal end will be weakened. There is no "best way" to brace the distal end, though some people have found suitable solutions. Personally, I just add extra ladder pieces around the region of the loading block, and that has worked I guess. And don't sweat asking a lot of questions, all of yours have been good ones. Plus, this is the way that we get better and learn from each other!
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Re: Boomilever B/C

Postby sciencecat42 » January 19th, 2019, 10:41 am

As far as I know, the bracing is mainly meant to keep the compression members from twisting or bowing. A 5cm segment without bracing should be fine.


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