Science Olympiad Competition Prep for the Structural Event
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- เผยแพร่เมื่อ 30 ก.ย. 2024
- This video is all about how to prepare your structural balsa device for competition. I go over several tricks and tips including data collected during dry-box and baking of an example bridge.
When you talked about the oven, all I could think about is when me and my partner were using hairdryers to vigorously dry the bridge
Thank you! But I was wondering, what is the best way to create a design log?
You are welcome! The design log for competition isn't something I have experience with as it wasn't required when I was coaching. The rules outline the specifics that they are expecting, but for me, I would say it's most important to document each build so you'd be able to select the same materials again and rebuild it exactly. That would include things like mass of each part, or group of parts, and sketches of any specific design aspects. You can see most of this in the notebook shots in my videos which would be a good start for a design log, but it looks like they want a bit more about things like specific test results, source of tools/hardware, etc. I would say, just document everything as much as you can and you'll be fine. Good luck!
Thank you for the amazing video's. You are so right , we decided to go with a conventional truss bridge because it was our first year and the kit offered was a truss. Our truss was great but not very competitive. But still, we learned a lot. I'm looking forward to next year! Thank you again.
hi, i tested out my bridge i built and it was able to hold the 15kg. however, I'm not sure if I should just use this bridge for my upcoming competition or should I build another bridge. I'm not sure if my bridge has weakened a lot. let me know your thoughts!
Hi! In general, it all depends on how close you were to the absolute maximum that bridge could hold before breaking. There is no 100% way to know that besides testing to failure, so you don't want to do that. If you didn't hear any cracking or other noises coming from the bridge during the test, it's probably fine to use again. If you are really concerned, if you have the ability to re-test it yourself, you can test it again before the competition. One approach is to test it to less than 15kg multiple times, say 11--12kg. That would test to see if any major damage was done during your 15kg competition loading. If it holds up to that, it gives you even more confidence it will hold 15kg again. If your bridge can actually hold 17-18+kg, you'd be able to test it again to 15kg as many times as you want and also use it in competition many times. Good luck!!
Thank you so much for spending lots of time making all the valuable videos! All of them are very helpful! I found out it is very difficult to duplicate a bridge as it is very hard to find the same material and use the same amount of glue every time. Would you recommend using the tested bridge to attend the competition which was tested to hold 15KG of sand and with no trace of damage? I also noticed the width of your Division B bridge at bottom was about 6cm. Have you got a chance to test a bridge around 5cm in width? What is the best width at bottom?
Yes, this problem quickly becomes a material optimization problem. It can be difficult (expensive) to get exactly what you are looking for. Pre-testing to 15kg is a good approach. It's the only way to know for sure you'll hold the whole amount, but by definition, your bridge will be a bit overdesigned. That is a tradeoff you'll have to decide on, there is no one right answer. I never tried optimizing this further, so I didn't try anything more narrow. What was "best" for me was this 5900 bridge, so around 6cm. That doesn't mean something better isn't out there to be discovered! Good luck!
this isamfZing thank you for the isnight howto buld a great bridge. hopefully one day i will hvae a 7g bridgd that can hold max just like you
Hi, you are a wealth of information. I have learned so much! Does 8 hours of dry time part of the 24 hours in the dehydration box? Or do you recommend letting flue dry before going into the box? Thanks again for shsring your passion for building
Hi! Thanks! I'm glad you are finding my videos helpful! You don't need to let the glue cure before putting the device into the dry box. Ideally, that process is for 24+ hrs, but in some cases I've seen that ~12 hrs total can be enough, although I wouldn't recommend that unless you find yourself building the night before a competition :)
Hi, I'm looking at your 2023 division B bridge. What density did you buy on specialized balsa for the balsawood? Was it medium density, or extra Heavy?
It was more like "light" density as specialized balsa classifies it. Check out this video to see why that is the case: th-cam.com/video/mzMFhd4SqP8/w-d-xo.html
Hi, I made it to the national science olympiad competition, and I really want to try and podium for bridge, so I want to optimize my weight and strength as much as possible. Do you have any recommendations on the best quality wood or grade of wood I should get to build my bridge with? I know like C grade balsa is stronger, but would using c grade make it heavier? Thank you for the effort you put in to your videos.
Hi Connor, congratulations of making Nationals and thanks for the positive feedback! C-grain balsa isn't magically stronger than anything else. It has the same density range, so you can buy it very light just like A/B grain. It does have a different grain structure which gives it slightly different properties, like being more rigid and less prone to bending. That makes it a very good option to use for compression cases (like the legs for our bridges). It is also more brittle, so you need to make sure you are constraining the legs properly with enough cross-bracing. Good luck at Nationals!
Can you share the brand of bin you are using in the video? Also, from your other videos, what type of sand do you use with your testing table? It clearly has little to no dust. Thank you!
In this video, I'm using a bin I bought locally at Target. The smaller ones are easy to find with sealed tops. The challenge was finding one big enough for Tower this year. I went with this one: www.amazon.com/gp/product/B0BKD1VMMB/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1 For the sand, the key is to use material made for sand blasting and not play sand. This is what I'm using now and it works great: www.amazon.com/gp/product/B0791W9MXL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
What would happen if the bridge accidentally breaks when they put the chain through it?
Well, the event supervisors never touch the device and the students are the ones responsible for setting it up, so if it happens to break during setup, it's basically a bad day and you get a zero. In all my competitions I never saw that happen though, the kids are pretty careful.
hello balsa, just interested will you be doing tower now??
Hi! Yes, I have already started some preliminary work on tower. I hope to have a series of videos out going over the basics some time this summer, even before the rules come out, so be sure to keep an eye out for those!
Greetings, I am lost on as how to use cross members in the pratt trust design. It would be a great help if you could make a video or a guide. Thanks!
For these bridge designs, I've found that the X cross member design I've shown here works best. For next year's towers, I'll compare the X design to a pratt design to see how it compares, but I suspect the X design will be best there as well
@@balsaengineering6686 I will apply the X cross membver design, thank you!
If we use drierite instead of silica gel as a desiccant to dry the bridge, is that also fine?
I've never used drierite, but it looks like it does basically the same thing, so it should work fine. If you have the humidity sensors in the bin you can check the results to make sure
Hello again sir. do you know if the bridge event will be up next year as well? Thank
This is the second year of bridges, so it won't be bridge again next year. The previous cycle was boomi, so most likely it will be Towers next year, but no guarantees.
will you make videos for towers?
@@890sigma Yes, for sure. I look forward to next season!
Hey there, awesome information and video. I just have a couple of questions about the gel packets that absorb moisture. How much packets should I use in one box for one bridge, if i have 2 bridges should i double the packets. Also, how long should we have the packets inside the box with the bridge, and once we use them can we use them again? Thank you so much!!!
Hi! Thanks! I like to use about 4 or 5 silica packs in a bin. That should be good regardless of how many bridges are in there. The real work they are doing is removing the moisture from the air, once that is done, the moisture leaves the bridge into the air. I've found if you can have them in there for at least 24hrs, that will do the job well. As for re-using the packets, it depends on how well sealed your bin is and how many times you have opened it. This is why I like to keep an RH meter inside in the bin like I show in the video. This will let you know if your silica packs need to be replaced. Before a big competition, we'd always replace the packs (or just add new ones). They are cheap and that way you are guaranteed the best results. Good luck!
Hi, thank you for all of your videos, they have been really helpful. Our team is flying to an in person competition, and I was wondering how you would suggest transporting the bridge. There will be lots of bumpiness and air pressure change, but I don't know how much those factors contribute to the strength of the bridge. I've even heard of teams building their bridge on site, but we would only have around 12 hours for the bridge to dry. Thanks!
I have never had to fly with one of these devices, but it shouldn't be a problem if it's packed safely. If you need to check the baggage, something like a hard Pelican case would be ideal. If you can find something to bring it on as carry-on, that might be the safest way. I would definitely take the risk of flying it rather than trying to build a new device and test it under 12 hrs. Good luck!
Thank you so much for putting so much time and effort into making these educational videos, they are inspirational. This is my 1st building this bridge but I’m having a hard time making all 4 legs level evenly. Also the top square seems to break easily when I load. Any helpful pointers would be greatly appreciated. Also which glue do you use?
Hi! I'm glad you find my videos useful! Don't get discouraged, building great devices involves a lot of practice and they'll get much better as you build more. For making things square, definitely try and use an assembly jig if possible. I have included the STL files I used in the 5900 video (for Div B): th-cam.com/video/LI5n4PJFTCg/w-d-xo.html and in the full build videos for Div C. If you have access to a 3D printer, these help a lot! If not, I'd still recommend trying to build some kind of assembly jig, even if it's out of Lego! As for glue, I made an entire video about that if you want to check it out. The short answer is 50 cps CA glue is what I prefer: th-cam.com/video/55lb2KzSiwg/w-d-xo.html Good luck!!
Hello sir. Some of my competitions make us pour the sand in the bucket in incraments using a smaller cup. I'm just wondering if this would ever cause my bridge to prematurely snap. Thank you sir for your videos.
While auto-loading usually allows for the maximum weight to failure, if your bridge can hold 15kg, you should still be able to get there by hand loading. The idea is similar to fast auto-loading in that you want to minimize the time your device is under load. With hand loading, that means being super fast in re-filling the cup, and then pouring the cup fast... but don't just dump the cup, but pour it fast, if that makes sense. You should still try and get the loading done as fast as possible (within reason).
Hi, I just want to let you know that your videos have been super helpful for beginner bridge builders like me. One question, do you know if the handheld miter shears all over Amazon work well for cutting balsa? I wanted to order the cutter you use from the website you posted in a comment on another video but it seems that they awfully overprice it ($27.50) for blades attached to a wooden block.
Thanks, I appreciate the positive feedback! I don't have any experience with the handheld shears. I agree that almost $30 is a bit expensive for the miter cutter. When I bought mine 6 or 7 years ago, they were much cheaper. That being said, I have found it's a great tool to have regardless of the price, but that doesn't mean something else couldn't work as well
Hi, I have used your build and expanded upon it and made a few of my own adjustments for my bridge and I think I have a good design for my bridge, but what type of balsa wood is the best regarding grain.
In general, C-grain is best for the compression pieces, but honestly, it's possible to build nationally competitive devices with any grain as the density and so many other build factors are more important than grain type. Good luck!!
I want to say thank you for making the videos because they are really helpful!
I was wondering if the stl files you mentioned in a different video are ready to print. thanks!
Thanks for the nice feedback! Yep, the stil files should be ready to go, especially the Div B ones which you can find in the description of this video: th-cam.com/video/LI5n4PJFTCg/w-d-xo.html For Div C, check the build videos for each part. You might have to scale the middle jig extension pieces, but I have instructions for that in the description as well
Your videos helped my partner and I get 4th in states. Thanks!
Congratulations, that is a fantastic result! I'm glad my videos were able to help your team out!
Absolutely love your videos, what plastic bin did you use for the dry box?
Thanks for the kind feedback! I typically buy my bins locally at Meijer or Target, but this link looks correct for what I'm using in a 4-pack: www.amazon.com/Sterilite-19344304-Gasket-Aquarium-Latches/dp/B00KL7VPWO/ref=sr_1_1?crid=3UGQWZAD2C4EY&keywords=Sterilite+19344304+54+Quart%2F51+Liter+Box%2C+Aquarium+Latches+and+Gasket&qid=1672073569&sprefix=sterilite+19344304+54+quart%2F51+liter+box%2C+aquarium+latches+and+gasket%2Caps%2C105&sr=8-1
how can i find the results of last years national bridge tournament with the weights of the bridges
They don't really publish that data freely. If you know someone who went to the national summer coaches workshop, the give out a pdf that has a graphs for both Div B and C, but they don't include the raw data. In general though, from what I've seen, the top 5 Div B scores last year went from about 5.9g (3390) to 7.1g (2820) and for Div C, about 7.1g (2820) to 8.9g (2250). FWIW, none of those scores apply in any way to this year's bridges though, so don't use them as a guide going forward
What is the model of the relativity humidity meter? Where did you get it from? How did you seal the box to make it air tight?
Just the bin top with the foam insert is enough to make the dry-box air tight enough to work well. This is the exact RH meter I'm using: www.amazon.com/gp/product/B07GNMKYCZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
where do you source your wood from?
I like to get my balsa from Specialized Balsa: specializedbalsa.com/products/balsa_sheets.php and my basswood from Fnabco: fnabco.com/collections/basswood-sticks
@@balsaengineering6686 thank you :)
Great Video! I never knew that balsa was so complicated!
Thanks!!
Hi, thank you for making all these amazing videos! One question I have regarding the oven and it would be great to hear your opinion! If we bake the bridge at a lower temperature but for longer, do you think that will affect the wood less, like less brittle? Thank you!
Hi! I'm glad you have found my videos helpful! I don't think baking the bridge at a lower temperature for longer would make any difference in how brittle the bridge is. It's brittle because all the water content gets removed from the wood, which is what results in the mass loss, which is the goal of this process to begin with.
Thank you for answering ! Also another question, is there anything that could possibly work better than the silica gel packet at absorbing moisture? Thank you!
@@mingh8167 I'm not sure, perhaps. The silica gel packs are all I've ever used for this as they are very cheap and convenient. If you are using an RH meter in your dry box you should be able to test some other desiccants if you want.
Do you know what balsa wood is good for each member between the 4-grain types including bass
The short answer is to use bass for pure tension components, C-grain for compression members, and A or B for the rest. That being said, you can still be highly competitive using any grain balsa for a build like this as it's not as important as many other aspects of the build.
@@balsaengineering6686 Thank you so much I was able to achieve a 3200 competition score during my recent invitational. But, I was wondering what members have to be dense.
@@SaatvicMahesh Congratulations on the 3200! I assume you are talking about Div B? 3200 means your bridge was 6.25g if it held the entire weight. We know < 4g bridges are possible, so probably every aspect of your bridge could be made lighter. You are now discovering the fun part of this event which is to try and optimize your build . You really have to build a lot and experiment once you have the basics down to see what works well for you. If you want something to shoot for, check out my 5900 score build which was 3.39g: th-cam.com/video/LI5n4PJFTCg/w-d-xo.html
Me and my partner have figured out a way to preserve the weight after baking for up to 24 hours before it starts to decline noticeable. However as you have mentioned it’s a lot of effort and it does involve some dry ice and we don’t know if we want to do that much for our completion.
Interesting! Yeah, I can imagine it's possible if you can put your device into extreme conditions (like using dry ice) and using a really well sealed container - probably better than a simple plastic bin. Most likely not worth the effort for the minimal gains, but it's cool that you were able to do it!
A plastic bin was what we used interestingly but we covered the whole thing in plastic wrap and taped the top shut. We put the dry ice down than a layer of cardboard and finally our bridge. It’s very intricate and we think we may take it to our competition like that because it’s a very long drive to Syracuse and we do have a potential gain of about 3-500 points
@@EmmettFerguson-rs9dw Good luck!! Be sure to let me know how it goes!
Thanks for the video! Also, what do you think are the most significant rule changes for the event this year from last year?
You are welcome! Well, compared to last year, no pass-through block is a big change for both divisions. For Div C, lowering the loading block to no more than 1cm above the testing plane makes it very challenging. I would say overall, Div B is much easier than last year and Div C is harder
@@balsaengineering6686 Thanks so much! Are there any other smaller changes that have been made.
The rule manual is just a bit long and I want to ensure I don't miss anything
@@connor-db7ch Yes, there are other changes as well including the width requirements depending on Div B or C. The Bridge rules are only 4 pages, I highly recommend you study the official rules document to fully understand the changes. BTW, they make the changes from the previous year bold to make it easier to read.
I was wondering if you could share the link to the airtight box in the video?
I typically buy these locally at Target or Meijer, but this looks like the same one I have in a 4-pack: www.amazon.com/Sterilite-19344304-Gasket-Aquarium-Latches/dp/B00KL7VPWO/ref=sr_1_1?crid=3UGQWZAD2C4EY&keywords=Sterilite+19344304+54+Quart%2F51+Liter+Box%2C+Aquarium+Latches+and+Gasket&qid=1672073569&sprefix=sterilite+19344304+54+quart%2F51+liter+box%2C+aquarium+latches+and+gasket%2Caps%2C105&sr=8-1
@@balsaengineering6686 Thanks!
@@balsaengineering6686 I was also wondering what type of grain pattern is the best and what did you use on your Div B Bridge? A, B, or C?
@@bindurajagopalan1688 For this particular build, I think it was C grain which is good in compression. You can still do quite well with basic A or B or AB mix which is much cheaper. I would recommend starting with that and once you have your build optimized, then look into using C-grain at least for the legs