Boomilever B/C

[sciencecat42]

a number of kids at the Div B Centerville competition had the bolt out at 42.5 CM from the testing wall, having misread the rules. They must have thought that the inside edge of the block was to be 40 CM. This, of course is incorrect. It should be dimensioned from the wall to the CENTERLINE of the bolt to be at least 40 CM, and no more than 45 CM (although I have no idea why there is a maximum)

Also, FWIW, many, many Div B teams were way above the 20 CM drop line. Many as high or higher than Div C (at 15 CM). Still scratching my head on that one! Maybe thinking that by going shorter, they save weight? No clue!

To give them the benefit of the doubt, I'll often construct my boomilevers with a centimeter or so of tolerance just to be on the safe side.

[Anonymous15]

Hi everyone!

So I'm trying to build a testing setup for me to test boomilevers so that I can work out any building complications before invitationals. I am aware of the testing setup's general appearance, but I have nothing that I can use to build it right now. I also have no power tools or anything like that. Do any of you have any suggestions on things I can use/what I should buy to constuct a testing setup? Also, I don't really know how to build a testing setup, so if anyone could give any feedback, I would greatly appreciate it!

Additionally, I was going through my designs, and I was wondering how to get the tension members aligned with the compression members in such a way that both the tension and compression members will attach perfectly perpendicular to the wall. Are there any calculations to get this perfectly right, or is this something that requires estimation?

Lastly, is a jig necessary for this event? I know that you definitely need a jig for towers, but apart from the base and the distal end, the construction of the boomilever doesn't seem that complex. Would a jig be necessary to hold anything together?

Thank you all so much!

[MadCow2357]

in all honesty its pretty disappointing how you only care about your score and your placement based on a simple mistake the ES did.

Actually, it's a combination of two mistakes.

Mistake 1: ES decided that TheChiScientist's boom was too long based on a misinterpretation of the rules.

Mistakes happen, ES aren't always as well prepared as we'd like, and don't always know the rules as well as some of the competitors. That's why the really bad mistake is mistake 2:

Mistake 2: ES didn't tell TheChiScientist that they were getting tiered, so there wasn't an opportunity for TheChiScientist to address this with the ES. To my mind, this is a much bigger mistake than the rules misunderstanding in mistake 1.

TheChiScientist's disappointing result required the ES to make both mistakes.

There we go! That's the biggest mistakes that were made! Anyways I'm not really too concerned as I will be making contact with UChicago so they can correct these mistakes in time for their Div B Invitational.

To be honest, I think we can all stop with the opinions about Chi's appeal and stuff. I believe that he has handled it remarkably well, considering that he was pretty much in the unknown for the duration of the competition. Moral of the story: know that supervisors will make mistakes, so be eagle-eyed about their handling, scoring, etc. of your device

[Anonymous15]

Just reposting so it doesn't get lost in the other forum posts:

Hi everyone!

So I'm trying to build a testing setup for me to test boomilevers so that I can work out any building complications before invitationals. I am aware of the testing setup's general appearance, but I have nothing that I can use to build it right now. I also have no power tools or anything like that. Do any of you have any suggestions on things I can use/what I should buy to constuct a testing setup? Also, I don't really know how to build a testing setup, so if anyone could give any feedback, I would greatly appreciate it!

Additionally, I was going through my designs, and I was wondering how to get the tension members aligned with the compression members in such a way that both the tension and compression members will attach perfectly perpendicular to the wall. Are there any calculations to get this perfectly right, or is this something that requires estimation?

Lastly, is a jig necessary for this event? I know that you definitely need a jig for towers, but apart from the base and the distal end, the construction of the boomilever doesn't seem that complex. Would a jig be necessary to hold anything together?

Thank you all so much!

[MadCow2357]

Just reposting so it doesn't get lost in the other forum posts:

Hi everyone!

So I'm trying to build a testing setup for me to test boomilevers so that I can work out any building complications before invitationals. I am aware of the testing setup's general appearance, but I have nothing that I can use to build it right now. I also have no power tools or anything like that. Do any of you have any suggestions on things I can use/what I should buy to constuct a testing setup? Also, I don't really know how to build a testing setup, so if anyone could give any feedback, I would greatly appreciate it!

Additionally, I was going through my designs, and I was wondering how to get the tension members aligned with the compression members in such a way that both the tension and compression members will attach perfectly perpendicular to the wall. Are there any calculations to get this perfectly right, or is this something that requires estimation?

Lastly, is a jig necessary for this event? I know that you definitely need a jig for towers, but apart from the base and the distal end, the construction of the boomilever doesn't seem that complex. Would a jig be necessary to hold anything together?

Thank you all so much!

1. Buy some plywood, have Home Depot cut it for you. They can do that . You'll have to give them the lengths, of course. Use a hammer and nails to attach everything, not hard.

2. For both the tension and compression members to be perpendicular... ummm Not sure if I'm understanding your question correctly. Could you elaborate?

3. A jig is not required.

[Anonymous15]

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!

[Cow481]

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

[Carrot]

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?

[MadCow2357]

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.

[Anonymous15]

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!